CN115167060A - Apparatus and method for generating frequency-stabilized microcavity optical frequency comb - Google Patents

Abstract

The present disclosure presents an apparatus suitable for producing a frequency-stabilized microcavity optical frequency comb, comprising: a light source section configured to emit a light beam; a beam splitting device configured to split the light beam emitted by the light source part into a plurality of first light beams and transmit the first light beams; a light source frequency determining unit connected to the first output port of the beam splitting device, determining an adjustment frequency based on absorption of the first light beam by atoms in the light source frequency determining unit, and adjusting a frequency of emitting the second light beam by the light source section based on the adjustment frequency; the resonant microcavity is connected with the light source frequency determining unit, and the second light beam generates a first microcavity optical frequency comb in the resonant microcavity; and the modulation unit is arranged between the second output port of the beam splitting device and the resonant microcavity and is configured to modulate the second light beam into a third light beam with repetition frequency information based on the repetition frequency of the first microcavity optical frequency comb, and the third light beam generates a second microcavity optical frequency comb in the resonant microcavity.

Description

Apparatus and method for generating frequency-stabilized microcavity optical frequency comb

Technical Field

The present disclosure relates to the field of microcavity optical frequency combs, and more particularly, to a device and method for generating a frequency-stabilized microcavity optical frequency comb.

Background

The optical frequency comb behaves in the frequency domain as a series of equally spaced frequency comb teeth enabling direct locking covering all wavelengths within its frequency range and can be traced to microwave frequency standards. The optical frequency comb mainly comprises a mode-locked laser optical frequency comb, an electro-optic optical frequency comb, a quantum cascade laser optical frequency comb and a microcavity optical frequency comb. The microcavity optical frequency comb has the characteristics of integration, low power consumption, high repetition frequency, wide wavelength band and the like, and has important application value in the fields of coherent light communication, precision spectroscopy, optical ranging and the like.

How to accurately regulate and stabilize the frequency spectrum of the optical-frequency comb is important for applying the microcavity optical-frequency comb, the frequency spectrum of the microcavity optical-frequency comb is usually determined by the repetition frequency and the offset frequency, but the acquisition of the offset frequency is difficult and the requirement on the spectrum broadening is high. On the other hand, the existing scheme for regulating and stabilizing the frequency spectrum of the optical frequency comb needs a reference system with larger volume, which is not beneficial to miniaturization.

Disclosure of Invention

To at least partially overcome at least one of the above-mentioned technical drawbacks or other inventions, at least one embodiment of the present disclosure proposes an apparatus and method for generating a frequency-stabilized microcavity optical frequency comb, which can output a frequency-stabilized microcavity optical frequency comb by providing a light source frequency determining unit and a modulating unit, and whose comb tooth frequency can be directly determined by an atomic transition line.

According to one aspect of the present invention, there is provided an apparatus adapted to produce a frequency-stabilized microcavity optical frequency comb, comprising: a light source section configured to emit a light beam; a beam splitting device configured to split the light beam emitted by the light source part into a plurality of first light beams and transmit the first light beams; a light source frequency determining unit connected to a first output port of the beam splitting device, determining an adjustment frequency based on absorption of the first light beam by atoms in the light source frequency determining unit, and adjusting a frequency at which a second light beam is emitted based on the adjustment frequency by the light source section; the resonant microcavity is connected with the light source frequency determining unit, and the second light beam generates a first microcavity optical frequency comb in the resonant microcavity; and the modulation unit is arranged between the second output port of the beam splitting device and the resonant microcavity and is configured to modulate the second light beam into a third light beam with the repetition frequency information based on the repetition frequency of the first microcavity optical frequency comb, and the third light beam generates a second microcavity optical frequency comb in the resonant microcavity.

In some embodiments, the light source frequency determination unit comprises: the frequency doubling crystal is connected with the first output port of the beam splitting device and is configured to perform frequency conversion on the first light beam so that the wavelength of the converted first light beam is matched with the transition energy level of the atoms; the atomic gas chamber is connected with the frequency doubling crystal, and the first light beam after frequency conversion is absorbed by atoms in the atomic gas chamber and then emitted; a photodetector configured to convert an optical signal of the first light beam absorbed by the atoms in the atomic gas cell into an electrical signal; and a feedback system coupled to the photodetector and configured to calculate an error signal based on the electrical signal and determine the adjustment frequency based on the error signal.

In some embodiments, the modulation unit comprises: an electro-optical modulator disposed between a second output port of the beam splitting apparatus and the resonant microcavity, configured to modulate the second light beam; and the microwave source is connected with the electro-optical modulator and is configured to modulate the electro-optical modulator, wherein the modulation signal frequency of the microwave source is set based on the repetition frequency of the first microcavity optical frequency comb, so that the third light beam obtained after modulation by the electro-optical modulator has the repetition frequency information of the first microcavity optical frequency comb.

In some embodiments, further comprising: a plurality of transmission units, through which the third light beam is emitted into the resonant microcavity in a single direction; and an auxiliary unit connected to the resonant microcavity and configured to emit an auxiliary beam to balance thermal effects with the generation of a microcavity optical frequency comb within the resonant microcavity.

In some embodiments, the auxiliary beam is injected unidirectionally into the resonant microcavity through the transmission unit.

In some embodiments, the plurality of transmission units comprises: a fiber polarization controller disposed between the light source section and/or the auxiliary unit and the resonant microcavity, configured to control polarization of the third light beam and/or the auxiliary light beam; and the optical fiber isolator is connected with the optical fiber polarization controller and is configured to enable the third light beam and/or the auxiliary light beam to be emitted into the resonant microcavity in a single direction.

In some embodiments, the plurality of transmission units further comprises: an optical fiber amplifier having one end connected to the light source section and/or the auxiliary unit and the other end connected to the optical fiber polarization controller, the optical fiber amplifier being configured to amplify the power of the third light beam and/or the auxiliary light beam.

In some embodiments, the feedback system comprises: an oscilloscope configured to obtain a saturation absorption line of the atom based on the electrical signal; a modem to obtain the error signal based on absorption peaks in the saturated absorption line; and proportional-integral-derivative feedback means for determining the adjustment frequency based on the error signal.

In some embodiments, the atomic gas cell is a rubidium atomic gas cell.

According to another aspect of the present invention, there is provided a method of producing a frequency-stabilized microcavity optical frequency comb using the above apparatus, comprising: after the first light beam is emitted into the light source frequency determining unit, determining the adjusting frequency through absorption of atoms on the first light beam so as to keep the frequency of the second light beam within a preset range; modulating the second beam of light into a third beam of light with the repetition frequency information based on a repetition frequency of a first microcavity optical frequency comb generated within the resonant microcavity by the second beam of light; and the third light beam is emitted into the resonant microcavity and locks the repetition frequency through an injection locking process, thereby generating a second microcavity optical frequency comb in the resonant microcavity.

According to the device and the method for generating the frequency-stabilized microcavity optical frequency comb, the frequency of the light beam emitted by the laser can be stably locked to the transition energy level of the atom by arranging the light source frequency determining unit, and the second light beam locked to the transition energy level of the atom can generate the first microcavity optical frequency comb with stable central frequency in the resonant microcavity. The repetition frequency of the first microcavity optical frequency comb can be modulated onto the second light beam to form a third light beam by arranging the modulation unit, and the third light beam obtained after modulation has a frequency component similar to that of the first microcavity optical frequency comb, so that the purpose of stabilizing the repetition frequency of the first microcavity optical frequency comb can be achieved through an injection locking process after the third light beam is injected onto the first microcavity optical frequency comb. Therefore, after the third light beam is injected into the first microcavity optical frequency comb, a second microcavity optical frequency comb with frequency-stable comb teeth can be formed in the resonant microcavity; in addition, the frequency domain of each comb tooth of the formed second microcavity optical frequency comb can be directly determined by the transition frequency of atoms, so that a plurality of feedback systems and a plurality of additional reference light sources can be avoided, the complexity of the system is simplified, the detection of offset frequency can be avoided, the requirement on the spectrum broadening of the optical frequency comb system is reduced, and the method can be expanded into more microcavity optical frequency comb systems.

Drawings

FIG. 1 schematically illustrates a schematic diagram of an apparatus suitable for producing a frequency-stabilized microcavity optical frequency comb in accordance with an embodiment of the present disclosure;

FIG. 2 schematically illustrates a cross-sectional view of an apparatus suitable for producing a frequency-stabilized microcavity optical frequency comb after encapsulation of a resonant microcavity, in accordance with an embodiment of the disclosure;

FIG. 3 schematically illustrates a flow chart of a method for producing a frequency-stabilized microcavity optical frequency comb using the above-described apparatus, in accordance with an embodiment of the present disclosure; and

figure 4 schematically illustrates a frequency-stabilized microcavity optical frequency comb schematic produced using the above-described method, according to an embodiment of the present disclosure.

Description of the reference numerals

1: a light source unit;

2: a beam splitting device;

3: a light source frequency determining unit;

31: frequency doubling crystals;

32: an atomic gas cell;

33: a photodetector;

34: a feedback system;

4: a resonant microcavity;

5: a modulation unit;

51: an electro-optic modulator;

52: a microwave source;

6: a plurality of transmission units;

61: an optical fiber amplifier;

62: an optical fiber polarization controller;

63: a fiber isolator;

7: an auxiliary unit;

8: an optical fiber;

9: an optical fiber array;

10: a waveguide.

Detailed Description

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity, and like reference numerals refer to like elements throughout.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It is to be understood that such description is merely illustrative and not intended to limit the scope of the present invention. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.

To facilitate understanding of the technical aspects of the present invention by those skilled in the art, the following technical terms will now be explained.

Where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). Where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.).

Fig. 1 schematically illustrates a schematic diagram of an apparatus suitable for producing a frequency-stabilized microcavity optical frequency comb in accordance with an embodiment of the present disclosure.

As shown in fig. 1, the apparatus for generating a frequency-stabilized microcavity optical frequency comb according to the present disclosure includes a light source unit 1, a beam splitting device 2, a light source frequency determining unit 3, a resonant microcavity 4, and a modulating unit 5.

Specifically, the light source section 1 is configured to emit a light beam. The beam splitting means 2 is configured to transmit the light beam emitted from the light source section 1 by splitting it into a plurality of first light beams. The light source frequency determining unit 3 is connected to the first output port of the beam splitting device 2, determines an adjustment frequency based on absorption of the first light beam by atoms in the light source frequency determining unit 3, and adjusts the frequency at which the light source section 1 emits the second light beam based on the adjustment frequency. The resonant microcavity 4 is connected with the light source frequency determining unit 3, and the second light beam generates a first microcavity optical frequency comb in the resonant microcavity 4; the modulation unit 5 is arranged between the second output port of the beam splitting device 2 and the resonant microcavity 4, and is configured to modulate the second light beam into a third light beam with repetition frequency information based on the repetition frequency of the first microcavity optical frequency comb, and the third light beam generates a second microcavity optical frequency comb within the resonant microcavity 4.

According to the apparatus adapted to generate the frequency-stabilized microcavity optical frequency comb of the above-described embodiment of the present disclosure, by splitting the light beam emitted from the light source section 1 into a plurality of first light beams via the beam splitting device 2, the adjustment frequency to be adjusted for the light source section 1 can be determined by the absorption of the first light beams by the atoms in the light source frequency determining unit 3. Specifically, the absorption of the first light beam by atoms in the light source frequency determination unit 3 can be determined by atomic absorption lines. For example, the frequency of the light beam emitted from the light source unit 1 may be adjusted to be at the atomic absorption peak, so that the frequency of the light beam is locked to the transition level of the atom. For example, the frequency of the light beam emitted from the light source unit 1 can be adjusted by observing the change of the atomic absorption peak in real time, so that the light beam emitted from the light source unit 1 is stably located on the same atomic absorption peak. The light source part 1 can adopt pump laser, and the beam splitting device 2 can adopt an optical fiber beam splitter. It should be noted that the first light beam and the second light beam may be continuously changed, for example, the adjusted second light beam emitted after being split by the beam splitting device 2 may become a new first light beam to be emitted into the light source frequency determining unit 3.

Furthermore, after a second light beam which is adjusted and locked to the transition energy level of atoms is emitted into the resonant microcavity 4 to generate a first microcavity optical frequency comb, the repetition frequency of the first microcavity optical frequency comb is modulated onto the second light beam, and then a third modulated light beam is emitted into the resonant microcavity 4, so that the microcavity optical frequency comb with stable frequency can be determined. For example, the modulation unit 5 may be any device capable of performing a frequency modulation operation by modulating the repetition frequency of the first microcavity optical frequency comb onto the second optical beam by the modulation unit 5.

According to the device for generating the frequency-stabilized microcavity optical frequency comb disclosed by the embodiment of the disclosure, the frequency of the light beam emitted by the laser can be stably locked to the transition energy level of the atom by arranging the light source frequency determining unit 3, and the second light beam locked to the transition energy level of the atom can generate the first microcavity optical frequency comb with stable center frequency in the resonant microcavity 4. The modulation unit 5 is arranged to modulate the repetition frequency of the first microcavity optical frequency comb onto the second light beam to form a third light beam, and the modulated third light beam has a frequency component similar to that of the first microcavity optical frequency comb, so that the purpose of stabilizing the repetition frequency of the first microcavity optical frequency comb can be achieved after the third light beam is injected onto the first microcavity optical frequency comb. Therefore, after the third light beam is injected into the first microcavity optical frequency comb, a second microcavity optical frequency comb with stable comb tooth frequency can be formed in the resonant microcavity 4, the frequency domain of each comb tooth of the formed second microcavity optical frequency comb can be directly determined by the transition frequency of atoms, and then a plurality of feedback systems and a plurality of additional reference light sources can be avoided from being arranged, the complexity of the system is simplified, meanwhile, the detection of offset frequency can be avoided, the requirement on frequency spectrum broadening of the optical frequency comb system is reduced, and the optical frequency comb system is expanded into more microcavity optical frequency comb systems.

In some embodiments, light source frequency determining unit 3 comprises frequency doubling crystal 31, atomic gas cell 32, photodetector 33, and feedback system 34.

Specifically, the frequency doubling crystal 31 is connected to the first output port of the beam splitting device 2, and is configured to perform frequency conversion on the first light beam so as to match the wavelength of the converted first light beam with the transition energy level of the atom. The frequency doubling crystal 31 can be lithium niobate frequency doubling crystal, the atomic gas chamber 32 is connected with the frequency doubling crystal 31, and the first light beam after frequency conversion is emitted after being absorbed by atoms in the atomic gas chamber 32. The atomic gas cell 32 may be a rubidium atomic gas cell. The photodetector 33 is configured to convert an optical signal of the first light beam absorbed by the atoms in the atom gas cell 32 into an electrical signal. A feedback system 34 is connected to the photodetector 33 and is configured to calculate an error signal based on the electrical signal and to determine an adjustment frequency based on the error signal.

Further, after the first light beam is incident on frequency doubling crystal 31, frequency doubling crystal 31 can convert the frequency of the first light beam, for example, the wavelength of the light beam before entering frequency doubling crystal 31 is 1560.48nm, and the wavelength of the light beam after passing through frequency doubling crystal 31 is 780.24nm, so that the wavelength of the frequency doubled light beam can be matched with the transition energy level of the atoms in atom gas chamber 32, and thus the atoms in atom gas chamber 32 can be transitioned after the light beam enters atom gas chamber 32, and the saturated absorption lines of the atoms can be observed under the condition of scanning the absorbed light beam. The photodetector 33 converts the optical signal of the atomic saturation absorption line into an electrical signal. The feedback system 34 can determine the adjustment frequency required to adjust the light source unit 1 by the error signal after converting the electrical signal obtained by the photodetector 33 into the error signal, and can detect and adjust the frequency of the light beam emitted by the light source unit 1 in real time through the above process, so that the light source unit 1 emits a stable light beam, and the emitted light beam is locked to the transition energy level of the atom.

In some embodiments, feedback system 34 may include an oscilloscope, a proportional-integral-derivative feedback device, and a modem.

In particular, an oscilloscope may be used to observe the saturation absorption lines of atoms based on the electrical signal converted by the photodetector 33. The modem can calculate an error signal based on the absorption peak in the saturated absorption line. The proportional-integral-derivative feedback means may determine the adjustment frequency of the light-saving source section 1 based on the error signal, the light source section 1 emits a stable light beam and the emitted light beam may be locked to the atomic transition level.

In some embodiments, the modulation unit 5 comprises an electro-optical modulator 51 and a microwave source 52.

In particular, the electro-optical modulator 51 is arranged between the second output port of the beam splitting device 2 and the resonant microcavity 4, and is configured to modulate the second light beam. The microwave source 52 is connected to the electro-optical modulator 51 and configured to modulate the electro-optical modulator 51. The frequency of the modulation signal of the microwave source 52 is set based on the repetition frequency of the first microcavity optical frequency comb, so that the third light beam modulated by the electro-optical modulator 51 carries the repetition frequency information of the first microcavity optical frequency comb.

Further, the electro-optical modulator 51 may be modulated by the microwave source 52, and the second light beam may be modulated by the modulated electro-optical modulator 51. For example, by modulating the repetition rate of the first microcavity optical frequency comb onto the microwave source 52. The microwave source 52 modulates the electro-optical modulator 51, and the modulated electro-optical modulator 51 may modulate the second light beam into a third light beam. The frequency information of the third light beam may include at least one of: the frequency of the second beam of light, the frequency of the second beam of light plus the repetition rate of the first microcavity optical frequency comb and the frequency of the second beam of light minus the repetition rate of the first microcavity optical frequency comb. In other words, the third light beam can be modulated by the microwave source 52 and the electro-optical modulator 51 into a light beam with the information of the repetition frequency of the first microcavity optical frequency comb, and after the third light beam is incident into the resonant microcavity 4, the repetition frequency is locked to the microwave source 52 set based on the repetition frequency of the first microcavity optical frequency comb through an injection locking process, so that the frequency-stable microcavity optical frequency comb is generated in the resonant microcavity 4 without acquiring the offset frequency again.

In some embodiments, the apparatus adapted to produce a frequency-stabilized microcavity optical frequency comb further comprises a plurality of transmission cells 6 and auxiliary cells 7.

Specifically, the third light beam may be emitted unidirectionally into the resonant microcavity 4 through the plurality of transmission units 6. The auxiliary beam can also be emitted unidirectionally into the resonant microcavity 4 through the plurality of transmission elements 6.

The transmission unit 6 may include a fiber amplifier 61, a fiber polarization controller 62, and a fiber isolator 63. The fiber polarization controller 62 is disposed between the light source unit 1 and/or the auxiliary unit 7 and the resonant microcavity 4, and can be used to control the polarization of at least one of the third light beam and the auxiliary light beam. The fiber isolator 63 is connected to the fiber polarization controller 62 and can be used to allow at least one of the third beam and the auxiliary beam to enter the resonant microcavity 4 in a single direction, so as to prevent the reflected beam from damaging the fiber amplifier 61. The optical fiber amplifier 61 has one end connected to the light source unit 1 and/or the auxiliary unit 7 and the other end connected to the optical fiber polarization controller 62, and can amplify the power of at least one of the third beam and the auxiliary beam. The optical fiber isolator 63 can be replaced by an optical fiber circulator, and similar effects can be achieved. An auxiliary unit 7 is connected to the resonant microcavity 4 and can be used to emit an auxiliary beam to balance the thermal effects during the generation of the microcavity optical frequency comb within the resonant microcavity 4. Specifically, the resonant microcavity 4 has a strong thermal effect, and the auxiliary unit 7 emits an auxiliary beam in a direction opposite to the incident direction of the third beam, so that the thermal effect in the resonant microcavity 4 can be balanced, and the generation of the second microcavity optical frequency comb is assisted.

FIG. 2 schematically illustrates a cross-sectional view of an apparatus suitable for producing a frequency-stabilized microcavity optical frequency comb after encapsulation of a resonant microcavity, in accordance with an embodiment of the present disclosure.

As shown in fig. 2, the structure in which the resonant microcavity is packaged includes a resonant microcavity 4, an optical fiber 8, an optical fiber array 9, and a waveguide 10. Specifically, the light beams can form an array form after entering the optical fiber array 9 through the optical fiber 8 so as to be coupled with the waveguide 10, and the microcavity optical frequency comb can be generated after entering the resonant microcavity 4 through the waveguide 10. After the fiber array 9 and the waveguide 10 are aligned, they may be cured by using a low refractive index glue to ensure relative stability after packaging.

Fig. 3 schematically illustrates a flow chart of a method for generating a frequency-stabilized microcavity optical frequency comb using the above-described apparatus, in accordance with an embodiment of the present disclosure.

As shown in fig. 3, the method may include performing operations S301 to S303.

In operation S301: after the first light beam is incident on the light source frequency determining unit, the adjusting frequency is determined based on the absorption of the first light beam by atoms, so that the frequency of the second light beam is kept within a preset range.

In operation S302: the second beam is modulated into a third beam with repetition frequency information based on the repetition frequency of the first microcavity optical frequency comb generated within the resonant microcavity by the second beam.

In operation S303: a third beam of light is injected into the resonant microcavity and injection-locking the repetition frequency produces a second microcavity optical frequency comb within the resonant microcavity.

According to the embodiment of the present disclosure, the first light beam can be adjusted to the second light beam kept within the preset range by the light source frequency determining unit 3, that is, the light emitting unit can be made to emit a stable light beam, and in this process, the light beam emitted from the light source section 1 can be locked to the atomic transition level in consideration of the absorption of the light beam by atoms. Further, a stable second light beam is emitted into the resonant microcavity 4 to generate a first microcavity optical frequency comb, the repetition frequency of the first microcavity optical frequency comb is modulated to the second light beam to obtain a third light beam with repetition frequency information, the third light beam is emitted into the resonant microcavity 4 and then is injected onto the first microcavity optical frequency comb, a second microcavity optical frequency comb with frequency stabilization comb tooth frequency can be generated through an injection locking process, the frequency domain of each comb tooth of the generated second microcavity optical frequency comb can be directly determined by the transition frequency of atoms, multiple feedback systems and multiple additional reference light sources can be avoided, the complexity of the system is simplified, the detection of offset frequency can be avoided, the requirement on the spectrum broadening of the optical frequency comb system is further reduced, and the optical frequency comb system is expanded into more optical frequency comb systems.

The embodiment is as follows:

taking the light source 1 as the pump laser 1, the beam splitting device 2 as the fiber beam splitter 2, the frequency doubling crystal 31 as the lithium niobate frequency doubling crystal 31, the auxiliary beam as the auxiliary laser, and the resonant microcavity 4 as the micro-ring resonant microcavity 4.

After the pump laser 1 is split by the optical fiber beam splitter 2, a part of the laser is subjected to frequency conversion by the lithium niobate frequency doubling crystal 31. After the frequency-doubled pump laser 1 passes through the rubidium atom gas chamber 32, the photodetector 33 can convert the detected optical signal into an electrical signal and send the electrical signal to the feedback system 34. The feedback system 34 may detect the saturation absorption line of rubidium atoms through an oscilloscope, obtain an error signal through detecting a change of an absorption peak of the saturation absorption line of rubidium atoms and a modem, and determine an adjustment frequency of an emission beam of the pump laser 1 to be adjusted through the error signal and a proportional-integral-differential feedback device, so that the pump laser 1 emits a beam that is stable and frequency-locked to the saturation absorption line of rubidium atoms.

After the adjusted laser is emitted into the micro-ring resonant microcavity 4, a first microcavity optical frequency comb with stable central frequency can be generated, the repetition frequency of the first microcavity optical frequency comb is injected into the microwave source 52, the electro-optical modulator 51 is modulated by the microwave source 52, and the laser is modulated by the electro-optical modulator 51, so that the laser finally emitted into the micro-ring resonant microcavity 4 has repetition frequency information, and a second microcavity optical frequency comb with stable repetition frequency is generated.

Figure 4 schematically illustrates a frequency-stabilized microcavity optical frequency comb schematic produced using the above-described method, according to an embodiment of the present disclosure.

As shown in fig. 4, in an embodiment of the present disclosure, a second microcavity optical frequency comb can be generated after the auxiliary laser balances the intra-cavity thermal effects.

The microcavity optical frequency comb with stable center frequency and repetition frequency can be generated by the method.

In the embodiment of the present disclosure, the devices, for example, the rubidium atom air chamber, the electro-optical modulator, the lithium niobate crystal, and the micro-ring resonant microcavity, may be integrated, so that the apparatus suitable for generating the microcavity optical frequency comb may be miniaturized and integrated, and may be applied in a plurality of practical scenarios.

In light of the above description, those skilled in the art will recognize clearly that the present disclosure is applicable to apparatus and methods for generating frequency-stabilized microcavity optical frequency combs.

It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, used in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. In the event of possible confusion for understanding of the present disclosure, conventional structures or configurations will be omitted, and the shapes and sizes of the components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure.

Unless otherwise indicated, the numerical parameters set forth in the specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Generally, the expression is meant to encompass variations of ± 10% in some embodiments, 5% in some embodiments, 1% in some embodiments, 0.5% in some embodiments by the specified amount.

The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.

Further, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e. technical features in different embodiments may be freely combined to form further embodiments.

The above embodiments, objects, technical solutions and advantages of the present disclosure are further described in detail, it should be understood that the above embodiments are only examples of the present disclosure and should not be construed as limiting the present disclosure, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.

Claims (10)

1. An apparatus adapted to produce a frequency-stabilized microcavity optical frequency comb, comprising:

a light source section configured to emit a light beam;

a beam splitting device configured to split the light beam emitted by the light source part into a plurality of first light beams and transmit the first light beams;

a light source frequency determining unit connected to a first output port of the beam splitting device, determining an adjustment frequency based on absorption of the first light beam by atoms in the light source frequency determining unit, and adjusting a frequency at which a second light beam is emitted based on the adjustment frequency by the light source section;

the resonant microcavity is connected with the light source frequency determining unit, and the second light beam generates a first microcavity optical frequency comb in the resonant microcavity; and

a modulation unit disposed between the second output port of the beam splitting device and the resonant microcavity and configured to modulate the second beam into a third beam with the repetition frequency information based on the repetition frequency of the first microcavity optical frequency comb, the third beam generating a second microcavity optical frequency comb within the resonant microcavity.

2. The apparatus of claim 1, wherein the light source frequency determination unit comprises:

the frequency doubling crystal is connected with the first output port of the beam splitting device and is configured to perform frequency conversion on the first light beam so that the wavelength of the converted first light beam is matched with the transition energy level of the atoms;

the atomic gas chamber is connected with the frequency doubling crystal, and the first light beam after frequency conversion is emitted after being absorbed by atoms in the atomic gas chamber;

a photodetector configured to convert an optical signal of the first light beam absorbed by the atoms in the atomic gas cell into an electrical signal; and

a feedback system coupled to the photodetector and configured to calculate an error signal based on the electrical signal and determine the adjustment frequency based on the error signal.

3. The apparatus of claim 1, wherein the modulation unit comprises:

an electro-optic modulator disposed between the second output port of the beam splitting apparatus and the resonant microcavity and configured to modulate the second light beam; and

and the microwave source is connected with the electro-optical modulator and is configured to modulate the electro-optical modulator, wherein the frequency of a modulation signal of the microwave source is set based on the repetition frequency of the first microcavity optical frequency comb, so that the third light beam obtained after modulation by the electro-optical modulator has the repetition frequency information of the first microcavity optical frequency comb.

4. The apparatus of claim 1, further comprising:

a plurality of transmission units, through which the third light beam is emitted into the resonant microcavity in a single direction; and

an auxiliary unit connected to the resonant microcavity and configured to emit an auxiliary beam of light such that thermal effects are balanced if a microcavity optical frequency comb is generated within the resonant microcavity.

5. The apparatus of claim 4 wherein said auxiliary beam is injected unidirectionally into said resonant microcavity through said transmission element.

6. The apparatus of claim 5, wherein the plurality of transmission units comprises:

a fiber polarization controller disposed between the light source section and/or the auxiliary unit and the resonant microcavity, configured to control polarization of the third light beam and/or the auxiliary light beam; and

a fiber isolator coupled to the fiber polarization controller and configured to inject the third light beam and/or the auxiliary light beam unidirectionally into the resonant microcavity.

7. The apparatus of claim 6, wherein the plurality of transmission units further comprises:

an optical fiber amplifier having one end connected to the light source section and/or the auxiliary unit and the other end connected to the optical fiber polarization controller, the optical fiber amplifier being configured to amplify the power of the third light beam and/or the auxiliary light beam.

8. The apparatus of claim 3, wherein the feedback system comprises:

an oscilloscope configured to obtain a saturation absorption line of the atom based on the electrical signal;

a modem to calculate the error signal based on absorption peaks in the saturated absorption line; and

proportional-integral-derivative feedback means for determining the adjustment frequency based on the error signal.

9. The device of claim 3, wherein the atomic gas cell is a rubidium atomic gas cell.

10. A method of producing a frequency-stabilized microcavity optical frequency comb using the apparatus of any of claims 1-9, comprising:

after the first light beam is emitted into the light source frequency determining unit, determining the adjusting frequency through absorption of atoms on the first light beam so as to keep the frequency of the second light beam within a preset range;

modulating the second beam of light into a third beam of light with the repetition frequency information based on a repetition frequency of a first microcavity optical frequency comb generated within the resonant microcavity by the second beam of light; and

and the third light beam is emitted into the resonant microcavity and locks the repetition frequency through an injection locking process, so that a second microcavity optical frequency comb is generated in the resonant microcavity.

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