CN2469471Y - Light isolator - Google Patents

Abstract

The utility model relates to a light isolator. The utility model is characterized in that the front and the back sides of a nonreciprocity faraday rotator 1 are respectively provided with a first and a second optical wedges 21 and 22; the front side of the first optical wedge is provided with a polarization mould dispersion compensating sheet 3; the compensating sheet, the first optical wedge and the faraday rotator are fixed in a first steel ring 41; the second optical wedge is fixed in a second steel ring 42; the two steel rings are fixed in a magnetic pipe 5; an incidence optical fiber 71, an incidence aspherical mirror 81, an emergence aspherical mirror 82 and an emergence optical fiber 72 are respectively arranged in inner sealing pipes 61 and 62 at the front and the back sides of the magnetic pipe; the whole elements are arranged in a sleeve pipe 9. The separation angle of optical shafts of the optical wedges of the utility model is adjustable, and the light through faces of crystals in a light path are parallel. The utility model reduces the loss of forward transmission and increases isolating degree.

Description

Optoisolator

The utility model relates to a kind of optical passive component, particularly relates to a kind of low transmission loss, the optoisolator of high reflection, high-isolation.

Optoisolator mainly is used in laser instrument and the optical transmission system.In these systems, to the transmission requirement of light be for the light of forward transmitted wish can be in the process of transmission energy loss few more good more; And can stop for backlight, so-called backlight generally is that light is in the process of transmission forward, when passing through different transport vehicles, surface and the inner reflection that can take place in various degree at each carrier, these reflected energies cause the variation of light signal, if main is the variation that essence takes place for light that laser instrument is sent, cause that laser instrument warbles.In transmission system, external signal is loaded in the electric signal, and then electric signal is converted into light signal, and light signal is transmitted in optical cable, at exit end light signal is converted into electric signal then, will puts signal through demodulation then and be converted into our signal when beginning to transmit.

Optoisolator except for forward light with low-loss transmission, backlight is carried out outside the high degree of isolation, the another one performance is because the chromatic dispersion that different light interacts and causes, chromatic dispersion can cause the distortion of signal too.In order to solve the problem of distortion, known designs is to utilize the used crystalline material of birefringent wedge of Faraday rotator both sides and the difference of thickness to realize.

Existing optoisolator comprises twin-stage isolator and single-stage isolator, the twin-stage isolator all is to make on the basis of single-stage isolator, on structure, all be made up of two single-stage isolators, each isolator mainly is made of a Faraday rotator and the wedge (birefringence wedge type crystal) that is positioned at its both sides.The angle of its wedge optical axis is all fixed, and is uncontrollable.The subject matter that existing optoisolator exists is that chromatic dispersion and insertion loss are bigger, and isolation is lower.

The purpose of this utility model is to provide a kind of adjustable included angle of wedge optical axis, and the logical light face of each crystal in the light path is parallel, and the forward transmitted loss is little, and isolation is big, and the little optoisolator of polarization mode dispersion.

For achieving the above object, the utility model provides a kind of optoisolator, this isolator comprises nonreciprocity Faraday rotator 1 and wedge 2, it is characterized in that, both sides, front and back at nonreciprocity Faraday rotator 1 are respectively equipped with first, second wedge 21,22, be provided with polarization mode dispersion (PMD) compensation sheet 3 in the front side of first wedge, the polarization mode dispersion (PMD) compensation sheet, first wedge and nonreciprocity Faraday rotator are fixed in first steel loop 41, second wedge is fixed in second steel loop 42, first, second steel loop then is fixed in the magnetic tube 5, the interior tube sealing 61 of both sides before and after magnetic tube, be respectively equipped with incident optical 71 in 62, incident aspheric mirror 81 and outgoing aspheric mirror 82, outgoing optical fiber 72, all device is arranged in the sleeve pipe 9.

First wedge, 21 planes of incidence are relative with the exit facet of compensating plate, and place light path; The plane of incidence of nonreciprocity Faraday rotator 1 is relative with the exit facet of first wedge, and places light path; The plane of incidence of second wedge 22 is relative with the exit facet of Faraday rotator, and parallel with the logical light face of Faraday rotator, and places light path; Outgoing aspheric mirror 82 is relative with the exit facet of second wedge; The plane of incidence of polarization mode dispersion (PMD) compensation sheet 3 is relative with aspheric mirror, and parallel with the logical light face of logical light face of facing directly of first wedge and Faraday rotator, and is in the light path.

The angle of the optical axis of first, second wedge can be adjusted into consistent by rotating second steel loop with the anglec of rotation of Faraday rotator.

Incident optical 71 and outgoing optical fiber 72 are fixing with glass bushing 73,74 respectively, and aspheric mirror 81,82 is individually fixed in the same interior tube sealing 61,62 with glass bushing 73,74.

Glass bushing 73,74 is the inclined-plane by an end of aspheric mirror 81,82.

Polarization mode dispersion (PMD) compensation sheet 3 is between first wedge 21 and incident aspheric mirror 81, and its crystallographic axis polarity with wedge is opposite.

As seen from the above technical solution, the utility model is arranged at wedge, Faraday rotator and polarization mode dispersion (PMD) compensation sheet respectively in two steel loops, rotate steel loop and then can suitably regulate the angle of former and later two wedge optical axises, thereby increase the isolation of optoisolator; Because steel loop places magnetic tube, can guarantee the parallel of the logical light face of four crystal, reduced the loss of forward.With the logical light face of polarization mode dispersion (PMD) compensation sheet aspheric mirror near incident light, can increase the angle between the two-beam of backlight, therefore can increase the isolation of optoisolator and reduce polarization mode dispersion.

The utility model is described in further detail below in conjunction with drawings and Examples.

Fig. 1 is the utility model structural representation.

Fig. 2 is the utility model structure cut-open view.

Fig. 3 is the utility model structural principle synoptic diagram.

Fig. 4 is light forward transmitted synoptic diagram in optoisolator of the present utility model.

Fig. 5 is that light is from optoisolator output terminal incident synoptic diagram.

Consult Fig. 1, Fig. 2, a kind of improved optoisolator of the present utility model comprises nonreciprocity Faraday rotator 1, wedge 2, polarization mode dispersion (PMD) compensation sheet 3, steel loop 4, magnetic tube 5, interior tube sealing 6, optical fiber 7, aspheric mirror 8 and sleeve pipe 9, and wherein wedge 2 comprises first wedge 21, second wedge 22; Steel loop 4 comprises first steel loop 41 and second steel loop 42; Interior tube sealing 6 comprises interior tube sealing 61,62; Optical fiber 7 comprises incident optical 71 and outgoing optical fiber 72, and glass bushing comprises glass bushing 73,74; Aspheric mirror 8 comprises incident aspheric mirror 81 and outgoing aspheric mirror 82.Described incident optical 71 is located at the front end of optoisolator, and the one end is used for introducing incident light, and the other end is fixed with a columnar glass bushing 73.The outer end of glass bushing is the inclined-plane, penetrates in the back into optical fibers again with the reflected light that reduces in the process that light penetrates from optical fiber.Being provided with incident aspheric mirror 81 on the other side by the beveled end of glass bushing, incident light is collimated, aspheric mirror to the coupling effect of light will be good than the coupling effect of GRIN Lens many, a very big leap is arranged on performance and parameter.The glass bushing of aspheric mirror and fixed fiber is fixed in the same columnar interior tube sealing 61, and the used material of interior tube sealing is the metal material of Yi Shangxi.The rear end of optoisolator is provided with outgoing optical fiber 72, is used for receiving emergent light.This optical fiber is fixed in another glass bushing 74, and the front end of this glass bushing also is the inclined-plane, and its place ahead is provided with outgoing aspheric mirror 82 on the other side, is used for emergent light is collimated, and aspheric mirror 82 and glass bushing 74 are fixed in the same interior tube sealing 62.The middle part is provided with nonreciprocity Faraday rotator 1 in the optoisolator between two interior tube sealings 61,62, both sides are respectively equipped with first, second wedge 21,22 before and after it, they are the identical birefringence wedge shape crystal of structure, avoid like this distinguishing in the process of making.The angle of two wedge optical axises equals the angle of faraday's rotation, and this angle can be adjusted by rotating second steel loop 42.Can reduce walk-off by thickness and the wedge angle of designing two wedges.The first wedge front side is provided with polarization mode dispersion (PMD) compensation sheet 6, the material complementation of the material of this compensating plate and wedge, and promptly wedge is the positive axis crystal, compensating plate is negative axialite body so; If wedge is negative axialite body, then compensating plate is the positive axis crystal.Compensating plate can reduce the optical path difference of light through o light after the system and e light (seeing Fig. 4, Fig. 5) like this, thereby can reduce the polarization mode dispersion that produces because of the phasic difference of two-beam.Polarization mode dispersion (PMD) compensation sheet, first wedge 21 and faraday are fixed in first steel loop 41, and second wedge 22 is fixed in second steel loop 42, and first, second steel loop then is fixed in the magnetic tube 5.Magnetic tube is fixed in the middle part of sleeve pipe 9 with glue, and the material of sleeve pipe is identical with the material of interior tube sealing, and the collimating apparatus that the aspheric mirror 8 that is positioned at the isolator two ends and glass bushing constitute is located at the two ends of magnetic tube, is sealed in equally in the sleeve pipe 9.Therefore magnetic tube has become an integral body with two collimating apparatuss.Wherein all assemblies are all coaxial.

First wedge, 21 planes of incidence are relative with the exit facet of compensating plate, and place light path; The plane of incidence of nonreciprocity Faraday rotator 1 is relative with the exit facet of first wedge, and places light path; The plane of incidence of second wedge 22 is relative with the exit facet of Faraday rotator, and parallel with the logical light face of Faraday rotator, and places light path; Outgoing aspheric mirror 82 is relative with the exit facet of second wedge; The plane of incidence of polarization mode dispersion (PMD) compensation sheet 3 is relative with aspheric mirror 81, and parallel with the logical light face of logical light face of facing directly of first wedge and Faraday rotator, and is in the light path.

Principle of work of the present utility model can be illustrated in conjunction with Fig. 3～5.Among Fig. 3, a, c are left and right sides collimating apparatus (comprising optical fiber, glass bushing and aspheric mirror), and b is a magnetic tube, and a is injected in the magnetic tube after incident light is collimated, and light is through penetrating after the magnetic tube, and c is coupled in the outgoing optical fiber after emergent light is collimated.The effect of b mainly is to transmit with extremely low loss for forward luminous energy, and stops reflected light to penetrate from magnetic tube, and reflected light is injected among a again.

Further as shown in Figure 1, the front end of the glass bushing of fixed fiber adopts the inclined-plane, be because the surface of optical fiber and glass bushing is on same one side, when incident light is injected aspheric mirror from optical fiber when, reflection to a certain extent can take place, if face end directly on the surface of glass bushing, then reflected light can reenter in the optical fiber toward transmission back, this is very disadvantageous for laser instrument, so designed ramp structure, enters in the optical fiber to avoid reflected light.The light that comes out from optical fiber is not the light that collimates very much, therefore adds an aspheric mirror on the opposite of optical fiber, and the light that will penetrate from optical fiber focuses on, and makes light beam approach laser beam.

Fig. 4 shows the situation of light forward transmitted in optoisolator, as shown, be divided into two-beam during incident light process polarization mode dispersion (PMD) compensation sheet 3, i.e. two bunch plane of polarization mutually perpendicular ordinary light o light and extraordinary ray e light, though o light is different with the refractive index of e light in compensating plate, but o light is consistent with the transmission direction of e light in compensating plate, so do not have angle through o light after the compensating plate and e light, just has optical path difference between the two-beam.Be complementary because of compensating plate and first, second wedge to the contribution between the optical path difference of o light and e light again, thus on certain degree, compensated the optical path difference of total system, thus reduced polarization mode dispersion.

When light penetrates from compensating plate 3, and when arriving on the plane of incidence of first wedge 21, because the anisotropy of wedge, so there is an angle direction of propagation of the light of o light and e light.The angle of the direction of propagation of e light wave and light wave normal direction is provided by following formula: $\tan \left(\mathrm{\&alpha;}\right)=(1-\frac{{\mathrm{<figure-callout\; id="2"\; label="no"\; filenames="Y0120967300101.png"\; state="\{\{state\}\}">no</figure-callout>}}^2}{{\mathrm{ne}}^2})\&CenterDot;\frac{\tan \left(\mathrm{\&theta;}\right)}{1+\frac{{\mathrm{no}}^2\&CenterDot;{\tan \left(\mathrm{\&theta;}\right)}^2}{{\mathrm{ne}}^2}}$

Simultaneously in the process of propagating, the linear polarization face of o light is vertical with the optical axis of wedge, the plane parallel that the linear polarization face of e light and the optical axis of wedge and extraordinary ray wave vector are formed.

Behind this two-beam process nonreciprocity Faraday rotator 1, Faraday rotator has rotated the θ angle to the Faraday's light beam of process to a direction under the effect of saturation magnetic field, because the angle between two wedges, 21,22 optical axises is the θ angle, when so o light and e light pass through Faraday rotator and inject second wedge 22, the linear polarization face of o light is vertical with the optical axis of second wedge, the plane parallel that the linear polarization face of e light and the optical axis of second wedge and extraordinary ray wave vector are formed.Therefore, after this two-beam is through first and second wedges, becomes directional light and penetrate, assemble to be coupled in the outgoing optical fiber by the aspheric mirror 82 of exit end at last and penetrate.

Light moves towards as shown in Figure 5 from the light that output terminal enters optoisolator, light is injected from outgoing optical fiber 72, convergence through aspheric mirror is injected in second wedge 22, in second wedge, this Shu Guang is divided into linear polarization face mutually perpendicular ordinary light o light and extraordinary ray e light, by Faraday rotator rotation θ angle, because the nonreciprocity of Faraday rotator, so light is the sense of rotation in directive forward transmitted time still, at this moment, the linear polarization face of o light and the optical axis direction out of plumb of wedge, and the optical axis direction of the linear polarization face of e light and wedge is also not parallel, and all become certain included angle.Therefore two-beam also has an angle through its direction of propagation after second wedge.After the two-beam of angle was injected polarization mode dispersion (PMD) compensation sheet 3, angle did not reduce ground and propagates forward.After above-mentioned angle reached certain degree, light just can not be coupled in the incident optical 71, thereby plays the effect of an isolation for backlight.We can pass through the thickness and the Faraday's rotation angle of design wedge, thus the isolation of control isolator.

Claims (6)

1, a kind of optoisolator, comprise nonreciprocity Faraday rotator (1) and wedge (2), it is characterized in that, both sides, front and back at nonreciprocity Faraday rotator (1) are respectively equipped with first, second wedge (21), (22), be provided with polarization mode dispersion (PMD) compensation sheet (3) in the front side of first wedge, the polarization mode dispersion (PMD) compensation sheet, first wedge and nonreciprocity Faraday rotator are fixed in first steel loop (41), second wedge is fixed in second steel loop (42), first, second steel loop then is fixed in the magnetic tube (5), the interior tube sealing (61) of both sides before and after magnetic tube, (62) be respectively equipped with incident optical (71) in, incident aspheric mirror (81) and outgoing aspheric mirror (82), outgoing optical fiber (72), all device is arranged in the sleeve pipe (9).

2, optoisolator according to claim 1 is characterized in that, the plane of incidence of first wedge (21) is relative with the exit facet of compensating plate, and places light path; The plane of incidence of nonreciprocity Faraday rotator (1) is relative with the exit facet of first wedge, and places light path; The plane of incidence of second wedge (22) is relative with the exit facet of Faraday rotator, and parallel with the logical light face of Faraday rotator, and places light path; Incident aspheric mirror (81) is relative with the exit facet of second wedge; The plane of incidence of polarization mode dispersion (PMD) compensation sheet 3 is relative with aspheric mirror, and parallel with the logical light face of logical light face of facing directly of first wedge and Faraday rotator, and is in the light path.

3, optoisolator according to claim 1 is characterized in that, the angle of the optical axis of first, second wedge can be adjusted into consistent by rotating second steel loop with the anglec of rotation of Faraday rotator.

4, optoisolator according to claim 1, it is characterized in that, incident optical (71) and outgoing optical fiber (72) use glass bushing (73), (74) to fix respectively, and aspheric mirror (81), (82) and glass bushing (73), (74) are individually fixed in same interior tube sealing (61), (62).

5, optoisolator according to claim 4 is characterized in that, glass bushing (73), (74) are the inclined-plane by an end of aspheric mirror (81), (82).

6, optoisolator according to claim 1 is characterized in that, polarization mode dispersion (PMD) compensation sheet (3) is positioned between first wedge (21) and the incident aspheric mirror (81), and its crystallographic axis polarity with wedge is opposite.

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