EP2697874A1 - Erzeugung azimutal oder radial polarisierter strahlung in optischen wellenleitern - Google Patents
Erzeugung azimutal oder radial polarisierter strahlung in optischen wellenleiternInfo
- Publication number
- EP2697874A1 EP2697874A1 EP11718932.4A EP11718932A EP2697874A1 EP 2697874 A1 EP2697874 A1 EP 2697874A1 EP 11718932 A EP11718932 A EP 11718932A EP 2697874 A1 EP2697874 A1 EP 2697874A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- azimuthally
- grating
- optical waveguide
- radially polarized
- modes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/105—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type having optical polarisation effects
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
- H01S3/06712—Polarising fibre; Polariser
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/0675—Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
- G02B27/286—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/08018—Mode suppression
- H01S3/0804—Transverse or lateral modes
Definitions
- the invention relates to a device for producing azimuthally or radially polarized radiation by means of an optical waveguide, wherein the optical waveguide has a structure which is suitable for guiding azimuthal or radially polarized modes.
- Devices which emit radially or azimuthally polarized radiation are of great interest for a variety of applications in the field of science, medical technology, military technology or civil engineering, for example for material processing, microscopy or so-called optical tweezers. These applications require light sources with azimuthally or radially polarized radiation, in particular simple, stable, high-performance and cost-effective sources with high polarization purity.
- Optical waveguides in particular glass fibers, which have a structure which is suitable for guiding different azimuthally or radially polarized modes already exist in the prior art. So far, however, it has not succeeded satisfactorily to produce these modes stable and with little effort within the waveguide.
- CONFIRMATION COPY Possess property of azimuthal and radial polarization.
- the problem is that modes with approximately the same effective refractive index combine with each other, so that from the azimuthally or radially polarized modes, a predominantly linearly polarized beam is formed.
- the TE 0 i and TM 0 i modes combine with HE21 modes to form a beam with linear polarization. Waveguide structures that allow such combinations are referred to as "weakly-leading".
- a radially polarized mode can be deliberately excited by coupling a fundamental mode into the fiber with an offset (see T. Grosjean, D. Courjon and M. Spajer "An all-fiber device for generating and other polarized light beams ", Optics Communications, vol. 203, pp. 1-5, 2002).
- a special fiber design for example according to US 2009/0202191 A1
- a radially or azimuthally polarized mode can be generated.
- the fiber design allows the conversion of an existing linearly polarized beam.
- power can be coupled within the fiber from the fundamental mode into a respective radially or azimuthally polarized mode.
- the azimuthal or radially polarized modes in the optical waveguide have different effective refractive indices and within the optical waveguide a narrow-band grating, in particular a fiber Bragg grating is arranged, which is formed so that spectral distance between two azimuthally or radially polarized resonant modes is equal to or greater than their spectral bandwidth.
- the device according to the invention uses the principle of so-called "strong guidance" within the waveguide, where the azimuthally and radially polarized modes have different effective refractive indices and can thus be spectrally separated by a grating.
- the grating sets the difference in the effective refractive index into a difference
- the wavelength difference between the modes is very small, and in addition to the different effective refractive indices, it is necessary for the grating to be sufficiently spectrally narrow band to satisfactorily separate the azimuthally or radially polarized modes
- the spectral distance between two resonant modes should be at least as large as their bandwidth or larger.
- the wavelength difference ⁇ which is generated by a fiber Bragg grating with a grating period ⁇ , leaves calculate for two different effective refractive indices n e ffi and n e ff2 from the Bragg condition:
- the grating Since the wavelength difference ⁇ is very small, the grating must be sufficiently spectrally narrow band to allow sufficient polarization purity guarantee. If the grating is too broadband, the reflected modes overlap and the polarization purity decreases.
- an embodiment of the invention provides that the grating is an inhomogeneous fiber Bragg grating, which is designed so that it converts a mode of the waveguide, in particular the fundamental mode, in at least one azimuthally or radially polarized mode. Due to an inhomogeneous lattice constant of the fiber Bragg grating, a mode conversion can take place within the waveguide.
- a mode of a certain order is converted by the fiber Bragg grating in a mode of another order. For example, this makes it possible to convert the fundamental mode into a TEoi, a TM 0 1 and a HE 2 i mode.
- the optical waveguide with the grating arranged therein may be arranged outside or inside a laser oscillator.
- the radiation of the light source is coupled via optical elements in the strong leading waveguide structure.
- the grating reflects the light according to the wavelength either as azimuthally or radially polarized mode.
- the azimuthally or radially polarized radiation can be separated from the remaining radiation of the light source.
- the device according to the invention thus serves as an externally arranged polarization filter.
- the optical waveguide be doped with a laser-active material.
- the laser-active material is excited by the radiation of the light source.
- the two reflective elements of the oscillator are, on the one hand, the grating arranged inside the optical waveguide and, on the other hand, an optical element with wavelength-dependent reflection behavior, in particular an optical grating or a wavelength filter.
- the oscillator only supports one specific wavelength. If this wavelength is matched to the reflection properties of the arranged within the optical waveguide grating occurs within the optical waveguide and thus also within the oscillator, only an azimuthally or radially polarized mode.
- the invention further provides that the reflection properties of the grating can be influenced thermally or mechanically.
- the reflection behavior of the grid is influenced so that it is possible to switch between azimuthally and radially polarized modes. This results in a significant advantage over the prior art, in which can not be changed between azimuthal or radial polarization without much effort. Furthermore, it is possible to resort to commercially available components.
- the optical grating integrated into the waveguide can be both a reflection grating and a transmission grating.
- the device according to the invention can optionally - depending on the arrangement of the optical structure - perform a mode separation in transmission or reflection.
- a long-period grating (LPG) is recommended as the transmission grating, which couples the unwanted modes into the fiber cladding so that only the azimuthally or radially polarized mode is guided in the core.
- the invention further relates to a method for producing azimuthally or radially polarized radiation by means of an optical waveguide, wherein the optical waveguide azimuthally or radially polarized modes leads.
- the azimuthally or radially polarized modes in the optical waveguide have different effective refractive indices, the modes being filtered by means of a grating disposed within the optical waveguide such that their spectra do not overlap or overlap only slightly.
- Fig. 1 an apparatus according to the invention for
- FIG. 2 Generation of azimuthally or radially polarized radiation;
- Fig. 2 four different modes in strongly leading (left) and weakly leading (right) waveguides;
- Fig. 3 Spectral overlap on a mode of broadband fiber Bragg gratings reflected modes
- Fig. 4 spectral separation on a narrowband fiber Bragg grating of reflected modes
- Fig. 5 Mode conversion on an inhomogeneous
- 6 shows a device according to the invention arranged outside an oscillator
- 7 shows a device according to the invention arranged within an oscillator.
- the device according to the invention shown in FIG. 1 consists of an optical waveguide 1, a fiber Bragg grating 2, a light source 3 and a coupling-in optical system 4.
- the structure of the optical waveguide 1 must be designed to cancel the degeneracy of the modes, ie, to be "highly conductive.” This gives the azimuthal or radially polarized modes different effective indices of refraction the difference between the effective refractive indices of the modes is converted into a difference of the reflection wavelength 2. Since the wavelength difference between the modes is relatively small, the fiber Bragg grating 2 must have a sufficiently narrow band, in order to achieve a high polarization purity of the modes, is the fiber Bragg grating 2 closed broadband, the reflected modes overlap and the polarization purity decreases.
- FIG. 2 shows a radially polarized TM 0 i mode 5, two HE 2 i modes 6 and an azimuthally polarized TE 0 i mode 7 in the strongly leading (left) and degenerate (right) states within a rotationally symmetrical waveguide 1.
- FIG. 3 shows the case in which the fiber Bragg grating 2 is designed in such a broadband manner in relation to the wavelengths of the resonant modes 5, 6, 7 that the reflected modes 5, 6, 7 overlap.
- the effective refractive index of the modes 5, 6, 7 is shown, in the illustration on the right, the reflection spectrum of the fiber Bragg grating 2, belonging to the modes 5, 6, 7.
- FIG. 4 shows the result of the solution according to the invention, in which the modes 5, 6, 7 are reflected on a spectrally narrow-band fiber Bragg grating 2, so that an overlapping of the reflected modes 5, 6, 7 does not take place.
- the strongly leading, rotationally symmetric waveguide 1 with the narrow-band fiber Bragg grating 2 acts as a mode filter, which specifically spectrally separates the TM01 mode 5, the HE 2 i modes 6 and the TE 0 i mode 7.
- the device according to the invention is used to convert an existing mode 8 of the waveguide into an azimuthally or radially polarized mode 9, 11.
- an inhomogeneous fiber Bragg grating 2 is used, through which in the waveguide 1, which in each case have the same wavelength spacing between the fundamental mode 8 and the azimuthally or radially polarized modes 5, 7 propagating in the waveguide, so-called mode conversion takes place.
- a mode 8 of one order is converted by the inhomogeneous fiber Bragg grating 2 into another mode 9, 10, 11.
- the fundamental mode 8 of the rotationally symmetric waveguide is converted into the TM 0 i mode 9, the HE 2 i mode 10 and the TE 0 i mode 11.
- the spectrum shows conversion peaks
- the described mode filter can be arranged outside or inside an oscillator:
- FIG. 6 An arrangement outside an oscillator is shown for example in FIG. 6.
- a narrow-band light source 3 is coupled into the strongly guiding waveguide 1 via a collimating lens, a deflecting mirror, a beam splitter 12 and a coupling optics 4.
- the fiber Bragg grating 2 either the azimuthally or radially polarized mode 5, 7 is reflected according to the wavelength.
- the beam splitter 12 separates the azimuthally or radially polarized beam from that of the light source 3, so that the waveguide 1 with the integrated fiber Bragg grating 2 acts as an externally arranged mode filter.
- FIG. 7 An arrangement of the mode filter within an oscillator is shown in FIG. 7.
- the strongly guiding waveguide 1 is here doped with a laser-active material which is excited by the radiation of the light source 3.
- the radiation is coupled into the waveguide 1 via a coupling-in optical system 4.
- the oscillator is formed on the one hand by the fiber Bragg grating 2 and on the other hand by an external grating 13. Depending on the angle of the external grating 13, the oscillator only supports a certain wavelength. If this wavelength is tuned to a resonance wavelength of the fiber Bragg grating 3, only the azimuthally or radially polarized mode will oscillate.
- the reflection properties of the fiber Bragg grating 3 can be changed. This makes it possible - without changing the structure - to change between azimuthal and radially polarized modes. Another possibility is the change in the wavelength.
- the external influences are kept constant on the grid and changed over the wavelength of the light source 3 between azimuthal and radially polarized mode.
- the transmission grating 2 may be a long-period grating (LPG), which only allows the propagation of an azimuthally or radially polarized mode in the core.
- LPG long-period grating
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Physics & Mathematics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
Description
Claims
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/EP2011/001881 WO2012139598A1 (de) | 2011-04-14 | 2011-04-14 | Erzeugung azimutal oder radial polarisierter strahlung in optischen wellenleitern |
Publications (1)
Publication Number | Publication Date |
---|---|
EP2697874A1 true EP2697874A1 (de) | 2014-02-19 |
Family
ID=44626298
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP11718932.4A Withdrawn EP2697874A1 (de) | 2011-04-14 | 2011-04-14 | Erzeugung azimutal oder radial polarisierter strahlung in optischen wellenleitern |
Country Status (3)
Country | Link |
---|---|
US (1) | US9459403B2 (de) |
EP (1) | EP2697874A1 (de) |
WO (1) | WO2012139598A1 (de) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA2943502C (en) | 2014-03-21 | 2022-05-31 | Hypermed Imaging, Inc. | Compact light sensor |
US9655519B2 (en) | 2014-03-21 | 2017-05-23 | Hypermed Imaging, Inc. | Systems and methods for performing an imaging test under constrained conditions |
WO2017201093A1 (en) | 2016-05-17 | 2017-11-23 | Hypermed Imaging, Inc. | Hyperspectral imager coupled with indicator molecule tracking |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2330696A2 (de) * | 2009-11-25 | 2011-06-08 | Fujikura Ltd. | Laseroszillator und Filterverfahren |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6816260B2 (en) * | 2001-05-17 | 2004-11-09 | Thorlabs Gmbh | Fiber polarimeter, the use thereof, as well as polarimetric method |
US7496257B2 (en) * | 2001-07-03 | 2009-02-24 | Brown University Research Foundation | Method and apparatus for detecting multiple optical wavelengths |
US6816514B2 (en) * | 2002-01-24 | 2004-11-09 | Np Photonics, Inc. | Rare-earth doped phosphate-glass single-mode fiber lasers |
EP1359646A1 (de) * | 2002-04-30 | 2003-11-05 | ABB Schweiz AG | Faserlaser mit Modenunterdrückung |
US20070115551A1 (en) * | 2005-04-01 | 2007-05-24 | Alexis Spilman | Space-variant waveplate for polarization conversion, methods and applications |
US7599069B2 (en) * | 2005-05-06 | 2009-10-06 | The University Of Chicago | Vector beam generator using a passively phase stable optical interferometer |
US20070098023A1 (en) * | 2005-10-28 | 2007-05-03 | Quantronix Corporation | Fiber laser and methods manufacture and use |
US7778498B2 (en) | 2008-02-12 | 2010-08-17 | Ofs Fitel Llc | Systems and techniques for generating cylindrical vector beams |
-
2011
- 2011-04-14 WO PCT/EP2011/001881 patent/WO2012139598A1/de active Application Filing
- 2011-04-14 US US14/111,279 patent/US9459403B2/en not_active Expired - Fee Related
- 2011-04-14 EP EP11718932.4A patent/EP2697874A1/de not_active Withdrawn
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2330696A2 (de) * | 2009-11-25 | 2011-06-08 | Fujikura Ltd. | Laseroszillator und Filterverfahren |
Also Published As
Publication number | Publication date |
---|---|
US20140112612A1 (en) | 2014-04-24 |
WO2012139598A1 (de) | 2012-10-18 |
US9459403B2 (en) | 2016-10-04 |
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Legal Events
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17Q | First examination report despatched |
Effective date: 20180228 |
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RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: JOCHER, CHRISTOPH Inventor name: JAUREGUI MISAS, CESAR Inventor name: LIMPERT, JENS Inventor name: TUENNERMANN, ANDREAS |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 20200603 |