CN108153000B - Optical frequency comb generator with spectral line interval equal to optical fiber Brillouin frequency shift - Google Patents
Optical frequency comb generator with spectral line interval equal to optical fiber Brillouin frequency shift Download PDFInfo
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- CN108153000B CN108153000B CN201810007537.9A CN201810007537A CN108153000B CN 108153000 B CN108153000 B CN 108153000B CN 201810007537 A CN201810007537 A CN 201810007537A CN 108153000 B CN108153000 B CN 108153000B
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- 230000003287 optical effect Effects 0.000 title claims abstract description 60
- 239000013307 optical fiber Substances 0.000 title claims abstract description 30
- 230000003595 spectral effect Effects 0.000 title claims abstract description 16
- 230000010355 oscillation Effects 0.000 claims abstract description 12
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 14
- 230000010354 integration Effects 0.000 abstract description 2
- 210000001520 comb Anatomy 0.000 description 6
- 239000000835 fiber Substances 0.000 description 5
- 230000035559 beat frequency Effects 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000009022 nonlinear effect Effects 0.000 description 2
- 230000005693 optoelectronics Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
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- 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
- H01S3/30—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects
- H01S3/302—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects in an optical fibre
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/035—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect in an optical waveguide structure
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/39—Non-linear optics for parametric generation or amplification of light, infrared or ultraviolet waves
Abstract
The invention discloses an optical frequency comb generating device based on stimulated Brillouin scattering and electro-optical modulation, which utilizes a continuous wave laser, an electro-optical phase modulator, an optical fiber, a photoelectric detector and a radio frequency amplifier to form a feedback loop, generates a radio frequency signal with an oscillation frequency equal to the Brillouin frequency shift of the optical fiber, utilizes the radio frequency signal to drive another electro-optical modulator, generates an optical frequency comb with a spectral line interval equal to the Brillouin frequency shift of the optical fiber, and can change the spectral line interval of the optical frequency comb by adjusting the working wavelength of the laser or adopting the optical fibers with different Brillouin frequency shifts. Compared with the existing method for generating the optical frequency comb based on the electro-optical modulation, the method does not need to add an additional radio frequency signal to drive the modulator, so that the method has higher stability and lower phase noise, and is easier to realize the photoelectric integration.
Description
Technical Field
Electro-optically modulating continuous laser with radio frequency signals is a common method for generating optical frequency combs, and the realization of the method needs to add an external radio frequency source. The invention relates to an optical frequency comb generating device based on stimulated Brillouin scattering and electro-optical modulation, which utilizes a continuous wave laser, an electro-optical phase modulator, an optical fiber, an electro-optical detector and a radio frequency amplifier to form an oscillation loop, generates an oscillation mode with the frequency equal to the Brillouin frequency shift of the optical fiber, and utilizes the signal to drive another electro-optical modulator to generate an optical frequency comb. Therefore, the invention does not need to add radio frequency signals, can simultaneously generate radio frequency signals with the frequency of the optical fiber Brillouin frequency shift and optical frequency combs with spectral line intervals equal to the frequency, and the bandwidth of the generated optical frequency combs can be expanded by the cascade electro-optical modulator. The invention belongs to the technical field of photoelectric oscillators and optical frequency comb generators in the field of microwave photonics.
Background
In recent years, the generation of optical frequency combs has become one of the research hotspots in the field of microwave photonics because the optical frequency combs have wide application prospects in the fields of space navigation, optical precision measurement, arbitrary waveform generation and the like. The existing optical frequency comb generation methods are mainly divided into three types. The first is a mode-locked laser-based method, which requires a complex resonator to be constructed and the output spectrum is susceptible to the external temperature and the loss and dispersion of the waveguide medium such as optical fiber. The second method is to use the nonlinear effect in the optical fiber, which generates a larger number of spectral lines, but needs higher optical power to excite the nonlinear effect in the optical fiber, and the generated optical frequency comb has low tunability. The third is a method based on an electro-optical modulator, which has the outstanding advantages of good adjustability and high stability and is the most commonly used optical frequency comb generation method at present. For example, a phase modulator of continuous light from a laser with a radio frequency signal may produce an optical frequency comb comprised of a plurality of modulation sidebands. (reference [1 ]: J.Zhang, J.Yu, N.Chi, Z.Dong, X.Li, Y.Shao, J.Yu, and L.Tao, "fluorinated comb generation using phase modulators driven by functional frequency channel source with small frequency offset," Opt.Lett.38(4), pp.552-554, 2013). By cascading two intensity modulators and one phase modulator, driving the modulators with a 10GHz microwave signal, an optical frequency comb containing 38 spectral lines can be obtained within 1dB flatness (reference [2 ]: R.Wu, V.R.Superradiapa, C.M.Long, D.E.Leaird, and A.M.Weiner, "Generation of vertical optical frequency from continuous-wave lasers using a shielded input and phase modulators," Optit.Lett.35 (19), pp.3234-3236, 2010). In addition, by setting working points of the two cascade intensity modulators, the optical frequency comb generator with adjustable spectral line intervals and number can be designed. (reference [3 ]: X.Zou, W.Pan, and J.Yao, "Tunable optical comb generation based on carrier-supported interaction modulation and phase modulation," Chin.Opt.Lett.8(5), pp.468-470, 2010).
Although the above-mentioned methods based on electro-optical modulators can all obtain a flat optical-frequency comb, high-performance and low-noise microwave signal sources are required to provide driving signals, which not only has high cost, but also introduces noise and deteriorates the phase noise performance of the generated optical-frequency comb lines. Compared with the traditional radio frequency signal source, the Optoelectronic Oscillator has the advantages of high Q value, stable frequency, low phase noise, small volume and the like (reference [4 ]: Huang Pen, Cheng Zhang, Xiaopeng Xie, TaoSun, Pen Guo, Xiaoqi Zhu, Lixin Zhu, Weiwei Hu, and Zhang yuan Chen, "Tunable DC-60GHz RF Generation Utilizing a Dual-Loop Optoelectronic Oscillator Based on modulated Brillouin scattering" J.Lightwawa technical, 33(13), pp.2707-2715, 2015). In addition, the photoelectric oscillator replaces a traditional microwave signal source to drive the electro-optical modulator to generate the optical frequency comb, and the photoelectric integrated miniaturized optical frequency comb generator is easier to realize. Aiming at the situations, the optical frequency comb generator with spectral line spacing equal to the optical fiber Brillouin frequency shift is realized by utilizing the stimulated Brillouin scattering effect in the optical fiber and the phase modulator to generate photoelectric oscillation.
Disclosure of Invention
The invention discloses an optical frequency comb generator which does not need an additional microwave signal source and has spectral line intervals equal to optical fiber Brillouin frequency shift. Specifically, the optical frequency comb generator according to the present invention has a structure as shown in fig. 1. In the figure, laser output by a continuous wave laser (1) is divided into two branches by an optical coupler (2), light of a lower branch is amplified by an optical amplifier (3) and then is reversely input into an optical fiber (5) through a circulator (4), and stimulated Brillouin scattering in the optical fiber (5) is excited. The upper branch light generates modulation sidebands of +/-1 order through an electro-optical phase modulator (6). When the-1 order sideband of the signal light is within the gain bandwidth of the stimulated brillouin scattering of the optical fiber (5), this sideband will be amplified. The +1 order sideband, the amplified-1 order sideband and the carrier are input into an optical coupler (7) through a circulator (4) and divided into two paths, wherein one path of light is sent into a photoelectric detector (8) for photoelectric conversion, in the process, the +1 order sideband and the amplified-1 order sideband are respectively subjected to beat frequency with the optical carrier to obtain a microwave signal with the frequency equal to Brillouin frequency shift of an optical fiber (5), the signal is amplified by a radio frequency amplifier (9) and input into a radio frequency power divider (10) to be divided into two paths, and one path of signal is fed back to drive a phase modulator (6) to form an oscillation loop. The other path of radio frequency signal is divided into two paths by the radio frequency power divider (11) again, wherein one path of radio frequency signal is directly output and can be used as a radio frequency signal source or a system detection signal; the other path of laser passes through a radio frequency phase shifter (12), a radio frequency amplifier (13) and an adjustable radio frequency attenuator (14) and then drives an electro-optical modulator (15) to modulate the other path of laser output by the coupler (7) to generate an optical frequency comb, and the flat optical frequency comb can be obtained by adjusting the radio frequency phase shifter (12) and the adjustable radio frequency attenuator (14).
The invention has the following advantages:
1. compared with the traditional method, the invention does not need to input radio frequency signals from the outside to drive the modulator, thereby having higher stability and lower phase noise and being easier to realize photoelectric integration.
2. The optical frequency comb line interval realized by the invention is equal to Brillouin frequency shift of the optical fiber (5). Therefore, by adjusting the output wavelength of the continuous wave laser (1) or using an optical fiber (5) having different Brillouin frequency shifts, the interval between the spectral lines of the optical frequency comb can be changed.
3. One path of output of the radio frequency power divider (11) can be used as a radio frequency signal source, radio frequency oscillation with frequency interval equal to Brillouin frequency shift of the optical fiber (5) is output, and radio frequency oscillation signals with different frequencies can be output by adjusting the output wavelength of the continuous wave laser (1) or adopting the optical fiber (5) with different Brillouin frequency shifts.
4. The scheme provided by the invention also has good expansibility, a plurality of electro-optical intensity or phase modulators can be cascaded after the phase modulator (15), and the output signal of the radio frequency power divider (11) is subjected to power division again and then drives the cascaded electro-optical modulators, so that a flat optical frequency comb containing more spectral lines is output.
Drawings
FIG. 1: the invention relates to a device diagram of an optical frequency comb generator.
FIG. 2: the experimental spectrogram contains 9 flat optical frequency combs.
FIG. 3: a spectrogram of the obtained oscillation signal.
FIG. 4: and (4) obtaining a phase noise performance diagram of the oscillation signal through experiments.
Detailed Description
The scheme of the optical frequency generator provided by the invention has been verified through experiments, the experimental device is shown as figure 1, and the experimental process and the results are described as follows by combining the figures.
As shown in fig. 1, in the experiment, the operating wavelength of the tunable continuous wave laser is set to be 1550.2nm, the output power is 14dBm, the output light of the laser is divided into two paths by a 3dB coupler, the next path light is amplified by an erbium-doped fiber amplifier and reversely enters a nonzero dispersion displacement fiber with the length of 2km through a 2-port of a circulator, and the output power of the amplifier is 12dBm so as to excite the stimulated brillouin scattering effect in the nonzero dispersion displacement fiber. When the-1 order sideband output by the phase modulator is within the gain bandwidth of the stimulated brillouin scattering, this sideband will be amplified. The light output by the optical fiber is input to a circulator 10: the 90 coupler is divided into two paths, wherein one path with the splitting ratio of 90% is subjected to photoelectric conversion through a photoelectric detector, at the moment, the +1 order sideband and the amplified-1 order sideband are respectively subjected to beat frequency with a carrier to generate beat frequency signals with the frequency equal to the fiber Brillouin frequency shift, and then the beat frequency signals are amplified and fed back to the phase modulator to complete loop oscillation. And the stabilized oscillation signal drives the next stage electro-optic phase modulator. By adjusting the rf phase shifter and the variable rf attenuator, an optical frequency comb comprising 9 spectral lines within a 3dB bandwidth is finally obtained, as shown in fig. 2. Where the spacing of the spectral lines is equal to the frequency of the oscillating signal, which is equal to the brillouin shift of the non-zero dispersion shifted fiber, the experimental result is 10.67GHz, as shown in fig. 3. Finally, the single sideband phase noise of the oscillating signal was measured with a signal analyzer, as shown in FIG. 4, at a frequency offset of 10kHz, the phase noise was-85.0 dBc/Hz.
Therefore, the feasibility of the invention was verified experimentally.
In view of the above, the present invention achieves the intended objects.
Claims (4)
1. An optical frequency comb generator with spectral line spacing equal to optical fiber Brillouin frequency shift is characterized in that the optical frequency comb generator comprises the following components in connection relation: light output by a continuous wave laser (1) is divided into two branches by a first optical coupler (2), light of a lower branch is amplified by an optical amplifier (3) and then reversely input to an optical fiber (5) through a circulator (4), an electro-optic phase modulator (6) performs phase modulation on light of an upper branch, a modulated optical signal is input to a second optical coupler (7) through the optical fiber (5) and the optical circulator (4) and then divided into two paths, wherein one path of light is subjected to photoelectric conversion by a photoelectric detector (8), an output electric signal is amplified by a first radio frequency amplifier (9) and then divided into two paths by a first radio frequency power divider (10), one path of the light is fed back to the phase modulator (6), the other path of light is divided into two paths by a second radio frequency electro-optic power divider (11), one path of the light is directly output, the other path of light is subjected to driving of the electro-optic modulator (15) through a radio frequency phase shifter (12), a second radio frequency amplifier (13) and an adjustable radio, and modulating the other path of optical signal output by the second optical coupler (7) so as to generate an optical frequency comb.
2. An optical frequency comb generator as claimed in claim 1, characterized in that the electro-optical phase modulator is driven without an external input radio frequency signal, and the electro-optical oscillator formed by an internal feedback loop supplies the driving signal, and the oscillator comprises a continuous wave laser (1), a first optical coupler (2), an optical amplifier (3), an optical circulator (4), an optical fiber (5), an electro-optical phase modulator (6), a second optical coupler (7), a photodetector (8), a first radio frequency amplifier (9) and a first radio frequency power divider (10).
3. An optical frequency comb generator according to claim 1, characterized in that the optical frequency comb line interval generated is equal to the frequency of the internal photoelectric oscillation signal, which is equal to the brillouin frequency shift of the optical fiber (5), and the line interval of the output optical frequency comb is varied by adjusting the operating wavelength of the continuous wave laser (1) or by using optical fibers (5) with different brillouin frequency shifts.
4. The optical-frequency comb generator of claim 1, wherein after the electro-optical modulator (15), a plurality of electro-optical intensity or phase modulators are cascaded, and the output of the second rf power divider (11) is power-divided, phase-shifted and power-adjusted again to drive the newly cascaded modulators, thereby outputting a flat optical-frequency comb containing more spectral lines.
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| CN110707510A (en) * | 2018-07-09 | 2020-01-17 | 中国科学院半导体研究所 | Fourier domain mode-locked photoelectric oscillator based on stimulated Brillouin scattering |
| CN110518982A (en) * | 2019-07-15 | 2019-11-29 | 上海交通大学 | The method that cascade intensity modulator generates flat frequency comb and nyquist pulse |
| CN110911946B (en) * | 2019-11-28 | 2021-01-15 | 天津大学 | Comb-distance-adjustable low-phase-noise microwave frequency comb generator |
| CN111901042B (en) * | 2020-08-11 | 2022-03-11 | 中国电子科技集团公司第四十四研究所 | Phase modulation-based large dynamic signal demodulation model method |
| CN113568240A (en) * | 2021-07-02 | 2021-10-29 | 四川橙科通信技术研究院有限责任公司 | Optical frequency comb generation method and device for phase modulation and stimulated Brillouin scattering |
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| CN103941515B (en) * | 2014-04-09 | 2016-11-09 | 上海交通大学 | Comb frequency interval can the frequency comb generation device of frequency sweep and production method |
| CN107065390B (en) * | 2017-06-28 | 2019-06-21 | 吉林大学 | Microwave signal generating method and device based on stimulated Brillouin scattering effect and frequency comb |
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