CN113991404A - Noise signal generating device and method - Google Patents
Noise signal generating device and method Download PDFInfo
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- CN113991404A CN113991404A CN202111226049.5A CN202111226049A CN113991404A CN 113991404 A CN113991404 A CN 113991404A CN 202111226049 A CN202111226049 A CN 202111226049A CN 113991404 A CN113991404 A CN 113991404A
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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
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094069—Multi-mode pumping
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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
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0064—Anti-reflection devices, e.g. optical isolaters
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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
- H01S3/05—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
- H01S3/06729—Peculiar transverse fibre profile
- H01S3/06733—Fibre having more than one cladding
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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
- H01S3/05—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
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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
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094065—Single-mode pumping
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Abstract
The embodiment of the invention discloses a noise signal generating device and a noise signal generating method. The noise signal generating device comprises at least one pumping source, a wavelength division multiplexer, a first fiber grating, an active optical fiber, a delayer, a second fiber grating and a photoelectric detector; the first fiber bragg grating and the second fiber bragg grating form a Fabry-Perot resonant cavity, a pumping source is used for providing pumping light, light rays generated by the active fiber absorbing the pumping light generate relaxation oscillation in the Fabry-Perot resonant cavity, the relaxation oscillation forms a noise light signal with power fluctuation, and the noise light signal is incident to a photoelectric detector to generate a noise signal; the reflectivity of the first fiber grating is greater than that of the second fiber grating, and the retarder is used for adjusting the cavity length of the Fabry-Perot resonant cavity. The technical scheme of the embodiment of the invention can overcome the defects that the amplitude of the output signal of the existing noise source is small, the frequency stiffness is not easy to adjust, the requirement of a phase modulator can be met by adopting multi-stage amplification, and the like.
Description
Technical Field
The present invention relates to laser technology, and in particular, to a noise signal generating apparatus and a noise signal generating method.
Background
The high-power narrow-linewidth optical fiber laser source has important application value in the fields of industry, national defense, scientific research and the like due to the unique advantages of compact structure, good heat dissipation, good beam quality, high coherence and the like. The MOPA structure adopting a narrow-linewidth fiber laser seed source and then an amplifier is a main approach for obtaining the light source. But the single-mode output power of a single optical fiber amplified by the narrow-linewidth single-frequency laser is only hundreds of watts due to the nonlinear effect (stimulated brillouin scattering and the like) of the optical fiber. By widening the linewidth of the single-frequency laser to GHz level by using the phase modulator and then carrying out optical fiber amplification, the nonlinear effect threshold can be effectively improved, so that the output power is greatly improved.
The single-frequency laser phase broadening technology has the following basic principle: the single-frequency laser electric field part output after passing through the phase modulator is represented by the following formula:
wherein E isinFor input of electric field strength of single-frequency laser, Msin (ω)mt) represents the additional phase introduced by the phase modulator; m is the modulation depth, omegamIs the modulation angular frequency. Expanding the output light field by a Bessel function can be expressed as:
the result of electro-optic phase modulation is the generation of several sidebands, theoretically consisting of infinite sidebands, in a single frequency laser attachment. From the above formula, by changing the phase modulation depth M and the modulation frequency ωmThe additional phase is changed so that a different light field output can be obtained.
The broadened spectral width refers to the full width at half maximum of the waveform envelope composed of many sideband spectra. The modulation sidebands are required to be as rich as possible to obtain the best effect of nonlinear effect suppression, which requires EoutMore expansion terms and higher sideband amplitudes, thus requiring an increase in M or ωm. From M ═ pi V/VπIt can be known that to increase M, the modulation signal voltage on the phase modulator needs to be increased and the modulator with lower half-wave voltage needs to be selected; omegamDepending on the frequency of the modulated signal.
The noise sources mentioned above are generally obtained in the following ways:
1) a function generator is adopted to generate white noise or pseudo-random noise sources and the like, and the white noise or pseudo-random noise sources are amplified to a voltage value required by a phase modulator through a radio frequency amplifier. The advantage is that several waveforms can be formed, but under normal conditions, the amplitude of a GHz-level noise signal generated by a common electrical signal generator is usually very low (below 20 mV), the GHz-level noise signal cannot be directly used for a high-power amplifier (a high-power amplifier matched with an electro-optical modulator needs 400mV or more amplitude input), the required amplitude can be achieved only by amplifying for many times, and an amplification system is complex in structure, large in size and high in cost.
2) The ASE light source is added with a narrow-band filter and then generates a noise source signal through a photoelectric detector, the noise source signal is a good noise source, the structure is relatively simple, the bandwidth is about 12GHz and is relatively flat in the bandwidth range of 12GHz, the amplitude is only about 40-50mV @10GHz, the broadening needs larger noise amplitude, more sidebands are expected to be obtained, larger voltage is needed, correspondingly, multi-stage amplification is needed, and higher cost is generated.
Disclosure of Invention
The embodiment of the invention provides a noise signal generating device and a noise signal generating method, which aim to overcome the defects that the amplitude of an output signal of the conventional noise source is small, the frequency stiffness is not easy to adjust, the requirement of a phase modulator can be met by adopting multi-stage amplification and the like.
In a first aspect, an embodiment of the present invention provides a noise novice generating apparatus, including at least one pump source, a wavelength division multiplexer, a first fiber grating, an active fiber, a retarder, a second fiber grating, and a photodetector;
the output end of the pumping source is connected with the pumping input end of the wavelength division multiplexer, the output end of the wavelength division multiplexer is connected with the first fiber bragg grating, the active optical fiber and the delayer are connected between the first fiber bragg grating and the second fiber bragg grating, and the photoelectric detector is located at the output end of the second fiber bragg grating;
the first fiber bragg grating and the second fiber bragg grating form a Fabry-Perot resonant cavity, the pumping source is used for providing pumping light, the active fiber absorbs light rays generated by the pumping light to generate relaxation oscillation in the Fabry-Perot resonant cavity, the relaxation oscillation forms a noise optical signal with power fluctuation, and the noise optical signal is incident to the photoelectric detector to generate a noise signal;
wherein the reflectivity of the first fiber grating is greater than that of the second fiber grating, and the retarder is used for adjusting the cavity length of the Fabry-Perot resonant cavity.
Optionally, the reflectivity of the first fiber grating is greater than or equal to 99%, and the bandwidth is 1nm to 3 nm;
the reflectivity of the second fiber grating is greater than or equal to 5% and less than or equal to 10%, and the bandwidth is 0.2 nm-1 nm.
Optionally, the pump source is a multimode pump source, and the wavelength division multiplexer, the first fiber grating, the active fiber, the retarder, and the second fiber grating are all double-clad fiber devices.
Optionally, the optical fiber further comprises a cladding power stripper, and the cladding power stripper is located between the second fiber grating and the photodetector.
Optionally, the optical fiber grating further comprises an isolator, and the isolator is located between the second optical fiber grating and the photodetector.
Optionally, the optical fiber grating further comprises an adjustable attenuator, and the adjustable attenuator is located between the second optical fiber grating and the photodetector.
Optionally, the pumping source is a single-mode pumping source, and the wavelength division multiplexer, the first fiber grating, the active fiber, the retarder, and the second fiber grating are all single-clad fiber devices.
Optionally, the optical fiber grating further comprises an isolator, and the isolator is located between the second optical fiber grating and the photodetector.
Optionally, the optical fiber grating further comprises an adjustable attenuator, and the adjustable attenuator is located between the second optical fiber grating and the photodetector.
In a second aspect, an embodiment of the present invention further provides a noise signal generating method, which outputs a noise signal by using the above noise signal generating apparatus, where the noise signal generating method includes:
the pumping source generates pumping light, and the pumping light is transmitted to the active optical fiber after passing through the wavelength division multiplexer and the first fiber bragg grating;
the active optical fiber absorbs the pump light, and the generated light generates relaxation oscillation in a Fabry-Perot resonant cavity formed by the first fiber bragg grating and the second fiber bragg grating to form a noise optical signal with power fluctuation;
the noise optical signal is incident on a photodetector, generating a noise signal.
The noise signal generating device provided by the embodiment of the invention comprises at least one pumping source, a wavelength division multiplexer, a first fiber grating, an active fiber, a delayer, a second fiber grating and a photoelectric detector; generating pumping light by a pumping source, and transmitting the pumping light to an active optical fiber after the pumping light passes through a wavelength division multiplexer and a first fiber grating; the active optical fiber absorbs pump light to generate gain, the generated light generates relaxation oscillation in a Fabry-Perot resonant cavity formed by the first fiber bragg grating and the second fiber bragg grating, the relaxation oscillation forms a noise light signal with power fluctuation, and the noise light signal is incident to the photoelectric detector to generate a noise signal; the cavity length of the Fabry-Perot resonant cavity is adjusted through the delayer, so that the free spectral region of the Fabry-Perot resonant cavity is adjusted, and the adjustment of the noise signal frequency is realized. The noise signal generating device provided by the embodiment of the invention has the advantages of simple and flexible structure, convenience in manufacturing, high noise signal amplitude, adjustable frequency, certain bandwidth compared with a sine wave and the like.
Drawings
Fig. 1 is a schematic structural diagram of a noise signal generating apparatus according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of another noise signal generating apparatus according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of another noise signal generating apparatus according to an embodiment of the present invention;
FIG. 4 is a timing diagram of a noise signal according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a frequency spectrum of a noise signal according to an embodiment of the present invention;
FIG. 6 is a diagram of a frequency spectrum of a noise signal generated by a sinusoidal signal in the prior art;
FIG. 7 is a schematic diagram of a laser output spectrum of a noise signal generating apparatus according to an embodiment of the present invention;
fig. 8 is a flowchart illustrating a method for generating a noise signal according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. It should be noted that the terms "upper", "lower", "left", "right", and the like used in the description of the embodiments of the present invention are used in the angle shown in the drawings, and should not be construed as limiting the embodiments of the present invention. In addition, in this context, it is also to be understood that when an element is referred to as being "on" or "under" another element, it can be directly formed on "or" under "the other element or be indirectly formed on" or "under" the other element through an intermediate element. The terms "first," "second," and the like, are used for descriptive purposes only and not for purposes of limitation, and do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Fig. 1 is a schematic structural diagram of a noise signal generating apparatus according to an embodiment of the present invention. Referring to fig. 1, the noise signal generating apparatus provided in this embodiment includes at least one pump source 10 (one pump source 10 is illustrated in fig. 1, but not limited to the embodiment of the present invention), a wavelength division multiplexer 20, a first fiber grating 30, an active fiber 40, a retarder 50, a second fiber grating 60, and a photodetector 70; the output end of the pump source 10 is connected with the pump input end a of the wavelength division multiplexer 20, the output end b of the wavelength division multiplexer 20 is connected with the first fiber grating 30, the active fiber 40 and the retarder 50 are connected between the first fiber grating 30 and the second fiber grating 60 (the active fiber 40 is exemplarily shown to be connected with the first fiber grating 30 in fig. 1, in other embodiments, the positions of the active fiber 40 and the retarder 50 can be interchanged), and the photodetector 70 is located at the output end of the second fiber grating 60; the first fiber bragg grating 30 and the second fiber bragg grating 60 form a fabry-perot resonator, the pumping source 10 is used for providing pumping light, light rays generated by the pumping light absorbed by the active fiber 40 are subjected to relaxation oscillation in the fabry-perot resonator, the relaxation oscillation forms a noise light signal with power fluctuation, and the noise light signal is incident to the photoelectric detector 70 to generate a noise signal; wherein, the reflectivity of the first fiber grating 30 is greater than that of the second fiber grating 60, and the retarder 50 is used for adjusting the cavity length of the fabry-perot resonator.
The pump source 10 is used to provide pump light, and for example, a semiconductor laser may be used as the pump source 10. In this embodiment, each optical device may be an optical fiber device, thereby simplifying the coupling structure. In this embodiment, the first fiber grating 30 and the second fiber grating 60 form a fabry-perot F-P resonant cavity, and the common input end c of the wavelength division multiplexer 20 is vacant. The first fiber grating 30 is a high-reflectivity grating, the second fiber grating 60 is a low-reflectivity grating, and in specific implementation, optionally, the reflectivity of the first fiber grating 30 is greater than or equal to 99%, and the bandwidth is 1 nm-3 nm; the reflectivity of the second fiber grating 60 is greater than or equal to 5% and less than or equal to 10%, and the bandwidth is 0.2 nm-1 nm. The active fiber 40 is a rare-earth-doped fiber, and may be, for example, an erbium-doped fiber or an ytterbium-doped fiber. The delay device 50 may be a fiber delay line, and may be used to adjust the cavity length of the F-P resonant cavity, to achieve adjustment of the free spectral range, and to adjust the frequency of the noise signal. The photodetector 70 serves to convert the optical signal into an electrical signal, thereby outputting a desired noise signal.
It will be appreciated that in embodiments of the invention in which the structure in front of the photodetector 70 forms the light source of a common F-P cavity, relaxation oscillations, which are the dominant source of laser output power fluctuations, arise from nonlinear interactions between energy level particles on the gain medium and intracavity photons, and are manifested as changes in light intensity over time in certain frequency bands in damped oscillations, such that relative intensity noise is enhanced in relatively narrow frequency intervals around the frequency, i.e. relaxation oscillation peaks, which are common in the intensity noise spectrum measured by the photodetector, and which are at frequencies that are frequencies of relaxation oscillations
Typically between hundred kHz and MHz, where r ═ Wp/WpthFor pumping over-threshold, τ2For upper level particle lifetime, τRFor the passive resonator lifetime, it can be seen that the pump source, cavity loss, etc. are the main factors affecting the relaxation oscillation frequency.
Due to relaxation oscillation effect and the existence of different longitudinal modes in the cavity, noise signals with different frequencies exist after the output laser passes through the photoelectric detector, and the amplitude of the noise signals at the relaxation oscillation frequency can be as high as 520 mV. The frequency is determined by factors such as pump power, resonant cavity length, reflectivity and the like, so that the frequency of the noise signal is adjustable.
According to the technical scheme of the embodiment, the pumping light is generated by the pumping source and transmitted to the active optical fiber after passing through the wavelength division multiplexer and the first fiber grating; the active optical fiber absorbs pump light to generate gain, the generated light generates relaxation oscillation in a Fabry-Perot resonant cavity formed by the first fiber bragg grating and the second fiber bragg grating, the relaxation oscillation forms a noise light signal with power fluctuation, and the noise light signal is incident to the photoelectric detector to generate a noise signal; the cavity length of the Fabry-Perot resonant cavity is adjusted through the delayer, so that the free spectral region of the Fabry-Perot resonant cavity is adjusted, and the adjustment of the noise signal frequency is realized. The noise signal generating device provided by the embodiment of the invention has the advantages of simple and flexible structure, convenience in manufacturing, high noise signal amplitude, adjustable frequency, certain bandwidth compared with a sine wave and the like.
On the basis of the above technical solution, in a certain embodiment, optionally, the pump source 10 is a multimode pump source, and the wavelength division multiplexer 20, the first fiber grating 30, the active fiber 40, the retarder 50, and the second fiber grating 60 are all double-clad fiber devices. The laser formed by the double-clad fiber does not need a pumping source to be a single mode, and light beams are easier to couple.
Fig. 2 is a schematic structural diagram of another noise signal generation apparatus provided in an embodiment of the present invention, and exemplarily shows two pump sources 10 in fig. 2, and optionally, the noise signal generation apparatus further includes a cladding power stripper 80, where the cladding power stripper 80 is located between the second fiber grating 60 and the photodetector 70.
Since all the optical fiber devices in this embodiment are double-clad optical fiber devices, the pump light transmitted by the inner cladding is in the output light, and the pump light in the inner cladding can be filtered by arranging the cladding power stripper 80.
With continued reference to fig. 2, optionally, the noise signal generating apparatus further comprises an isolator 90 and an adjustable attenuator 100, the isolator 90 being located between the second fiber grating 60 and the photodetector 70, and the adjustable attenuator 100 being located between the second fiber grating 60 and the photodetector 70.
The isolator 90 can ensure the unidirectional transmission of the light beam, prevent the laser from returning to the F-P resonant cavity to influence the performance of the laser, and the adjustable attenuator 100 can reduce the power of the output light and prevent the photoelectric detector 70 from being damaged due to the overlarge optical power.
In another embodiment, the pump source 10 is a single-mode pump source, and the wavelength division multiplexer 20, the first fiber grating 30, the active fiber 40, the retarder 50 and the second fiber grating 60 are all single-clad fiber devices.
For example, fig. 3 is a schematic structural diagram of another noise signal generating apparatus according to an embodiment of the present invention. Referring to fig. 3, optionally, the noise signal generating apparatus further includes an isolator 90 and an adjustable attenuator 100, the isolator 90 is located between the second fiber grating 60 and the photodetector 70, and the adjustable attenuator 100 is located between the second fiber grating 60 and the photodetector 70.
It should be noted that the foregoing embodiments only show schematic structural diagrams of noise signal generating apparatuses provided in some embodiments of the present invention, and in other embodiments, simple combinations between the embodiments thereof are also within the scope of the embodiments of the present invention.
Fig. 4 is a timing diagram of a noise signal according to an embodiment of the present invention, and as can be seen from fig. 4, the amplitude of the noise signal generated according to the embodiment of the present invention can reach 520mV, which is a significant advantage compared to the prior art that only a few tens of millivolts of noise signal can be generated. Fig. 5 is a schematic frequency spectrum diagram of a noise signal according to an embodiment of the present invention, and fig. 6 is a schematic frequency spectrum diagram of a noise signal generated by using a sinusoidal signal according to the prior art, and it can be seen from fig. 5 and fig. 6 that the noise signal generated according to an embodiment of the present invention has more frequency components and has better performance. Fig. 7 is a schematic diagram of an output spectrum of a laser of the noise signal generating apparatus according to the embodiment of the present invention, and compared with an ordinary single-frequency laser, a spectrum of the laser in this embodiment has a certain spread, and a noise signal with better performance can be generated.
Fig. 8 is a schematic flow chart of a noise signal generating method according to an embodiment of the present invention, where the noise signal generating method according to this embodiment can be executed by any one of the noise signal generating apparatuses provided in the foregoing embodiments, and specifically includes the following steps:
and S110, generating pump light by a pump source, and transmitting the pump light to the active optical fiber after passing through the wavelength division multiplexer and the first fiber bragg grating.
The pumping source can be a semiconductor laser, in the specific implementation, the pumping source can be a multimode pumping source, and at the time, the wavelength division multiplexer, the first fiber grating, the active fiber, the retarder and the second fiber grating are all double-clad fiber devices; the pumping source can also be a single-mode pumping source, and at the moment, the wavelength division multiplexer, the first fiber grating, the active fiber, the retarder and the second fiber grating are all single-cladding fiber devices.
And S120, absorbing the pump light by the active optical fiber, and enabling the generated light to have relaxation oscillation in a Fabry-Perot resonant cavity formed by the first fiber grating and the second fiber grating to form a noise optical signal with power fluctuation.
Step S130, the noise optical signal is incident to the photodetector, and a noise signal is generated.
Wherein the photodetector converts the optical signal into an electrical signal, thereby outputting a desired noise signal. The delay is used for adjusting the cavity length of the F-P resonant cavity, realizing the adjustment of a free spectral region and adjusting the frequency of a noise signal.
According to the technical scheme of the embodiment, the pumping light is generated by the pumping source and transmitted to the active optical fiber after passing through the wavelength division multiplexer and the first fiber grating; the active optical fiber absorbs pump light to generate gain, the generated light is in a Fabry-Perot resonant cavity formed by the first fiber bragg grating and the second fiber bragg grating, relaxation oscillation is carried out to form a noise light signal with power fluctuation, and the noise light signal is incident to the photoelectric detector to generate a noise signal; the cavity length of the Fabry-Perot resonant cavity is adjusted through the delayer, so that the free spectral region of the Fabry-Perot resonant cavity is adjusted, and the adjustment of the noise signal frequency is realized. The noise signal generating device provided by the embodiment of the invention has the advantages of simple and flexible structure, convenience in manufacturing, high noise signal amplitude, adjustable frequency, certain bandwidth compared with a sine wave and the like.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A noise signal generating device is characterized by comprising at least one pumping source, a wavelength division multiplexer, a first fiber grating, an active fiber, a delayer, a second fiber grating and a photoelectric detector;
the output end of the pumping source is connected with the pumping input end of the wavelength division multiplexer, the output end of the wavelength division multiplexer is connected with the first fiber bragg grating, the active optical fiber and the delayer are connected between the first fiber bragg grating and the second fiber bragg grating, and the photoelectric detector is located at the output end of the second fiber bragg grating;
the first fiber bragg grating and the second fiber bragg grating form a Fabry-Perot resonant cavity, the pumping source is used for providing pumping light, the active fiber absorbs light rays generated by the pumping light to generate relaxation oscillation in the Fabry-Perot resonant cavity, the relaxation oscillation forms a noise optical signal with power fluctuation, and the noise optical signal is incident to the photoelectric detector to generate a noise signal;
wherein the reflectivity of the first fiber grating is greater than that of the second fiber grating, and the retarder is used for adjusting the cavity length of the Fabry-Perot resonant cavity.
2. The noise signal generating apparatus according to claim 1, wherein the first fiber grating has a reflectivity of 99% or more and a bandwidth of 1nm to 3 nm;
the reflectivity of the second fiber grating is greater than or equal to 5% and less than or equal to 10%, and the bandwidth is 0.2 nm-1 nm.
3. The noise signal generating apparatus of claim 1, wherein the pump source is a multimode pump source, and the wavelength division multiplexer, the first fiber grating, the active fiber, the retarder, and the second fiber grating are all double-clad fiber devices.
4. The noise signal generating apparatus according to claim 3, further comprising a cladding power stripper, the cladding power stripper being located between the second fiber grating and the photodetector.
5. The noise signal generating apparatus according to claim 3, further comprising an isolator between the second fiber grating and the photodetector.
6. The noise signal generating apparatus according to claim 3, further comprising an adjustable attenuator, the adjustable attenuator being located between the second fiber grating and the photodetector.
7. The noise signal generating apparatus of claim 1, wherein the pump source is a single-mode pump source, and the wavelength division multiplexer, the first fiber grating, the active fiber, the retarder, and the second fiber grating are all single-clad fiber devices.
8. The noise signal generating apparatus according to claim 7, further comprising an isolator between the second fiber grating and the photodetector.
9. The noise signal generating apparatus of claim 7, further comprising an adjustable attenuator positioned between the second fiber grating and the photodetector.
10. A noise signal generation method for outputting a noise signal by using the noise signal generation device according to any one of claims 1 to 9, the noise signal generation method comprising:
the pumping source generates pumping light, and the pumping light is transmitted to the active optical fiber after passing through the wavelength division multiplexer and the first fiber bragg grating;
the active optical fiber absorbs the pump light, and the generated light generates relaxation oscillation in a Fabry-Perot resonant cavity formed by the first fiber bragg grating and the second fiber bragg grating to form a noise optical signal with power fluctuation;
the noise optical signal is incident on a photodetector, generating a noise signal.
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| CN113867016A (en) * | 2021-09-26 | 2021-12-31 | 暨南大学 | PT symmetrical all-fiber optical isolator based on FP resonant cavity coupling system and method |
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