Phase-sensitive light amplification system with active impedance matching function

Abstract

The invention discloses a phase-sensitive light amplification system for active impedance matching. The phase-sensitive light amplification system comprises an F-P etalon, an OPA main cavity and an impedance matching module, the F-P etalon and the OPA main cavity form an OPA; the impedance matching module is used for performing frequency modulation on the input to-be-amplified signal light I and then outputting modulated signal light II; and according to the reflected light V of the OPA main cavity, which is detected in real time, generating a voltage control signal, and dynamically adjusting the parameters of the F-P etalon so as to ensure that the OPA cavity is always in an impedance matching state, the F-P etalon is used for sending the modulation signal light II and the pump light III into the OPA main cavity; and the OPA main cavity is used for performing power amplification processing on the modulation signal light II based on the pump light III to obtain a power amplification signal IV and outputting the power amplification signal IV. The F-P etalon is used as the input coupling mirror of the system, the reflectivity of the input coupling mirror is adjusted by monitoring and adjusting parameters of the F-P etalon, and it is ensured that the system keeps the optimal impedance matching state under different pumping power conditions.

Description

Technical Field

[0001] The invention belongs to the field of laser technology and quantum information technology, and in particular relates to an active impedance matching phase-sensitive optical amplification system. Background Art

[0002] Optical signal amplification has received increasing attention and application in modern communications, sensing, and laser technology. With the increasing demand for high-speed, large-capacity, and high-precision communications, the importance of optical signal amplifiers has become increasingly prominent. However, traditional optical amplifiers will inevitably introduce additional noise during the amplification process, which not only reduces the quality of the signal, but also has a negative impact on the overall performance of the system. These noises mainly come from the inherent defects of the amplifier itself and external environmental interference, which have an adverse effect on high-precision and high-sensitivity applications. Therefore, how to effectively control and reduce the noise introduced during the amplification process has become a key technical challenge.

[0003] Phase-sensitive optical amplification (PSA), as a special type of amplifier, can theoretically achieve noise-free amplification, and is therefore favored by researchers and engineers. Optical parametric amplification (OPA) technology is an effective solution for implementing PSA. Using pump light to amplify signal light can theoretically greatly increase signal strength without introducing additional noise. However, for continuous wave signals, the OPA system needs to adopt an impedance-matched optical cavity structure to achieve optimal gain and lowest noise figure. As the pump power changes, the impedance matching state of the OPA system may be destroyed, affecting the performance of the PSA. This characteristic of being sensitive to changes in pump power makes the existing PSA solution face many challenges in practical applications, and it is necessary to continuously adjust and optimize the system parameters to maintain its noise-free amplification effect. Summary of the invention

[0004] The technology of the present invention solves the problem: overcomes the shortcomings of the prior art, provides a phase-sensitive optical amplification system with active impedance matching, adopts an FP standard tool as the input coupling mirror of the system, and adjusts the reflectivity of the input coupling mirror by monitoring and adjusting the parameters of the FP standard tool to ensure that the system maintains the best impedance matching state under different pump power conditions.

[0005] In order to solve the above technical problems, the present invention discloses an active impedance matching phase-sensitive optical amplification system, comprising: an FP etalon, an OPA main cavity and an impedance matching module; wherein the FP etalon and the OPA main cavity are arranged on the same optical axis to form an OPA cavity;

[0006] The impedance matching module is used to frequency modulate the input signal light to be amplified I and output the modulated signal light II;

[0007] FP etalon, used to send modulated signal light II and pump light III into the OPA main cavity;

[0008] The OPA main cavity is used to power amplify the modulated signal light II based on the pump light III to obtain the power amplified signal IV and output it;

[0009] The impedance matching module is also used to generate a voltage control signal according to the reflected light V of the OPA main cavity detected in real time, and dynamically adjust the parameters of the FP standard tool to ensure that the OPA cavity is always in an impedance matching state.

[0010] In the above-mentioned active impedance matching phase-sensitive optical amplification system, the OPA main cavity is composed of a nonlinear medium and a plano-concave cavity mirror arranged in sequence according to the optical path.

[0011] In the above-mentioned active impedance matching phase-sensitive optical amplification system, the FP etalon is composed of a plane mirror, a driving element and a front end face of a nonlinear medium; wherein the plane mirror is arranged along the optical path, and the driving element is arranged on the front end face of the plane mirror.

[0012] In the above-mentioned active impedance matching phase-sensitive optical amplification system, a signal light input port A and a pump light input port A are arranged on the plane reflector, a signal light input port B and a pump light input port B are arranged on the nonlinear medium, and a signal light input port C and a pump light input port C are arranged on the plano-concave cavity mirror; wherein, the modulated signal light II and the pump light III are incident on the FP etalon through the signal light input port A and the pump light input port A respectively, and are output after being acted on by the FP etalon; the modulated signal light II and the pump light III emitted from the FP etalon are incident on the OPA main cavity through the signal light input port B and the pump light input port B respectively, and the relative phase of the modulated signal light II and the pump light III is locked; when the phase matching condition is met, the nonlinear medium generates a pulse containing a frequency of ω s The power amplified signal IV is outputted through the signal light output port C and the pump light output port C respectively.

[0013] In the above active impedance matching phase-sensitive optical amplifier system, when Δk = k p -2k s =0, it is determined that the phase matching condition is met; otherwise, the phase matching condition is not met; where Δk represents the phase mismatch, k p represents the wave vector of the pump light, k s Represents the wave vector of the signal light.

[0014] In the above-mentioned active impedance matching phase-sensitive optical amplification system, dynamically adjusting the parameters of the FP etalon refers to: dynamically adjusting the spacing d between the plane reflector and the front end surface of the nonlinear medium; wherein the reflectivity R of the FP etalon varies within the range of [0,1] as the spacing d changes.

[0015] In the above-mentioned active impedance matching phase-sensitive optical amplification system, the impedance matching module includes: a local oscillator, an electro-optic modulator, a beam splitter, a photodetector, a mixer, a low-pass filter and a PID controller; wherein the electro-optic modulator and the beam splitter are arranged along the optical path; the electro-optic modulator is connected to the mixer through the local oscillator; the photodetector is arranged on the reflected optical path of the beam splitter; the output end of the photodetector, the mixer, the low-pass filter and the PID controller are connected in sequence.

[0016] In the above-mentioned active impedance matching phase-sensitive optical amplifier system, the signal light I to be amplified is amplitude modulated by the electro-optical modulator to output the modulated signal light II; the modulated signal light II is incident on the OPA main cavity together with the pump light III after passing through the beam splitter through the FP standard device; the reflected light V of the OPA main cavity is incident on the photodetector through the beam splitter; the electrical signal output after passing through the photodetector is mixed with the modulated signal provided by the local oscillator on the mixer to generate an error signal; the high-frequency noise component in the error signal is filtered out by a low-pass filter to obtain a smooth error signal; the smooth error signal is processed by the PID controller to output a voltage control signal, and is loaded on the driving element to achieve adjustment of the spacing d.

[0017] In the above active impedance matching phase-sensitive optical amplification system, there is a phase difference between the modulation signal provided by the local oscillator to the electro-optical modulator and the modulation signal provided by the local oscillator to the mixer.

[0018] In the above-mentioned active impedance matching phase-sensitive optical amplification system, the front end face of the plane reflector, the rear end face of the nonlinear medium and the rear end face of the plano-concave cavity mirror are all coated with anti-reflection films with high transmittance for signal light and pump light; the rear end face of the plane reflector and the front end face of the nonlinear medium are coated with high reflection films with a reflectivity of 99% for signal light; and the front end face of the plano-concave cavity mirror is coated with a high reflection film with a reflectivity of 95% for signal light.

[0019] The present invention has the following advantages:

[0020] (1) The present invention discloses an active impedance matching phase-sensitive optical amplification system, which uses an FP etalon as the input coupling mirror of the system. The parameters of the FP etalon are dynamically adjusted through an impedance matching module to ensure the impedance matching of the OPA cavity, thereby ensuring that the system maintains the best impedance matching state under different pump power conditions. Compared with the previous OPA cavity structure, the present invention can ensure that the OPA cavity is always in the PSA optimal state under different pump powers.

[0021] (2) The present invention discloses an active impedance matching phase-sensitive optical amplification system, which has a simple structure and good compatibility with existing equipment. It can be realized by simply inserting a plane mirror into the existing single-ended cavity OPA. Compared with replacing the input coupling mirror or adjusting the pump power, it is more practical.

[0022] (3) The present invention discloses an active impedance matching phase-sensitive optical amplification system. By changing the distance d between the plane reflector and the front end surface of the nonlinear medium in the FP etalon, the transmittance of the FP etalon can be changed, so that the OPA cavity can meet the conversion between the ideal phase-sensitive amplification function and the function of generating a non-classical light field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a block diagram of a phase-sensitive optical amplification system with active impedance matching in an embodiment of the present invention;

[0024] Figure 2 is a schematic structural diagram of an OPA cavity in an embodiment of the present invention;

[0025] Figure 3 is a reflectivity variation curve diagram of a FP etalon in an embodiment of the present invention;

[0026] Figure 4 It is a schematic diagram of the relationship between the output noise coefficient of an active impedance matching phase-sensitive optical amplifier system and the normalized pump power in an embodiment of the present invention;

[0027] Figure 5 This is a working flow chart of an active impedance matching phase-sensitive optical amplification system in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] Reference Figure 1In this embodiment, the active impedance matching phase-sensitive optical amplifier system includes: FP etalon 1, OPA main cavity 2 and impedance matching module 3. Among them, FP etalon 1 and OPA main cavity 2 are arranged on the same optical axis to form an OPA cavity. Impedance matching module 3 is used to output modulated signal light II after frequency modulating the input signal light to be amplified I; FP etalon 1 is used as an input coupling mirror to send modulated signal light II and pump light III into OPA main cavity 2; OPA main cavity 2 is used to power amplify modulated signal light II based on pump light III to obtain power amplified signal IV and output it; impedance matching module 3 is also used to generate a voltage control signal according to the reflected light V of OPA main cavity 2 detected in real time, and dynamically adjust the parameters of FP etalon 1 to ensure that the OPA cavity is always in an impedance matching state.

[0030] In this embodiment, the OPA main cavity 2 is composed of a nonlinear medium 21 and a planar concave cavity mirror 22 arranged in sequence according to the optical path. The FP etalon 1 is composed of a plane mirror 11, a driving element 12 and the front end face of the nonlinear medium 21; the plane mirror 11 is arranged along the optical path, and the driving element 12 is arranged on the front end face of the plane mirror 11. Among them, dynamically adjusting the parameters of the FP etalon 1 refers to: dynamically adjusting the spacing d between the plane mirror 11 and the front end face of the nonlinear medium 21; the initial value of the spacing d can be set to 0.5cm, and the spacing d can be dynamically adjusted by driving a micromotor or a precision driving element such as a piezoelectric ceramic through the impedance matching module 3 to ensure the accuracy and response speed of the adjustment. The reflectivity R of the FP etalon 1 varies in the range of [0,1] with the change of the spacing d, such as Figure 3 shown.

[0031] Furthermore, the plane reflector 11 is provided with a signal light input port A and a pump light input port A, the nonlinear medium 21 is provided with a signal light input port B and a pump light input port B, and the plano-concave cavity mirror 22 is provided with a signal light input port C and a pump light input port C. The modulated signal light II and the pump light III are incident on the FP etalon 1 through the signal light input port A and the pump light input port A, respectively, and are output after being acted upon by the FP etalon 1. The modulated signal light II and the pump light III emitted from the FP etalon 1 are incident on the OPA main cavity 2 through the signal light input port B and the pump light input port B, respectively, and the relative phase θ (for example, θ=0) of the modulated signal light II and the pump light III is locked; when the phase matching condition is met, the nonlinear medium 21 generates a signal containing a frequency of ω s The power amplified signal IV is output through the signal light output port C and the residual pump light output port C respectively. p -2k s =0, it is determined that the phase matching condition is met; otherwise, the phase matching condition is not met; Δk represents the phase mismatch, kp represents the wave vector of the pump light, k s Represents the wave vector of the signal light.

[0032] In this embodiment, the impedance matching module 3 includes: a local oscillator 31, an electro-optic modulator 32, a beam splitter 33, a photodetector 34, a mixer 35, a low-pass filter 36 and a PID controller 37. The electro-optic modulator 32 and the beam splitter 33 are arranged along the optical path; the electro-optic modulator 32 is connected to the mixer 35 through the local oscillator 31; the photodetector 34 is arranged on the reflected optical path of the beam splitter 33; the output end of the photodetector 34, the mixer 35, the low-pass filter 36 and the PID controller 37 are connected in sequence.

[0033] Preferably, the working process of the impedance matching module 3 is as follows: the signal light I to be amplified is amplitude modulated by the electro-optical modulator 32, and the modulated signal light II is output; the modulated signal light II is incident on the OPA main cavity 2 together with the pump light III after passing through the beam splitter 33 and the FP standard device 1; the reflected light V of the OPA main cavity 2 is incident on the photodetector 34 through the beam splitter 33; the electrical signal output after passing through the photodetector 34 is mixed with the modulation signal provided by the local oscillator 31 on the mixer 35 to generate an error signal; the high-frequency noise component in the error signal is filtered out by the low-pass filter 36 to obtain a smooth error signal; the smooth error signal is processed by the PID controller 37 to output a voltage control signal, and is loaded onto the driving element 12 to adjust the spacing d.

[0034] Furthermore, there is a phase difference φ between the modulation signal provided by the local oscillator 31 to the electro-optical modulator 32 and the modulation signal provided by the local oscillator 31 to the mixer 35 .

[0035] Furthermore, the frequency is ω S After the signal light I to be amplified is frequency modulated by the impedance matching module 3, the modulated signal light II is output. In the process of phase-sensitive light amplification, the pump light energy is transferred to the signal light to achieve power amplification of the signal light.

[0036] In this embodiment, the plane reflector 11 has a reflectivity of 99% for signal light and a high transmittance for pump light. The front end of the nonlinear medium 21 has a reflectivity of 99% for signal light and a high transmittance for pump light; the rear end of the nonlinear medium 21 has a high transmittance for both signal light and pump light. The plane-concave cavity mirror 22 has a reflectivity of 95% for signal light. Figure 2As shown, the front end face of the plane reflector 11, the rear end face of the nonlinear medium 21 and the rear end face of the plano-concave cavity mirror 22 are all coated with anti-reflection films with high transmittance for signal light and pump light; the rear end face of the plane reflector 11 and the front end face of the nonlinear medium 21 are coated with high reflection films with a reflectivity of 99% for signal light; the front end face of the plano-concave cavity mirror 22 is coated with a high reflection film with a reflectivity of 95% for signal light.

[0037] In this embodiment, the nonlinear medium 21 is a material with second-order or third-order nonlinear characteristics, such as KTP crystal, silicon-based waveguide or nonlinear optical fiber, etc., which is used to implement a phase-sensitive optical amplification process.

[0038] In this embodiment, if Figure 4 As shown in FIG. 1 , the output noise coefficient of the active impedance-matched phase-sensitive optical amplifier system varies with the normalized pump power. In the impedance-unmatched state, the reflectivity of the fixed FP etalon 1 is 99%, and the reflectivity of the plano-concave cavity mirror 22 is 95%. The noise coefficient increases with the increase of the pump light power. In the impedance-matched state, the noise coefficient maintains the lowest noise coefficient at any pump light power.

[0039] In this embodiment, if Figure 5 As shown, the working process of the active impedance matching phase-sensitive optical amplification system is as follows:

[0040] Step 1: System initialization.

[0041] Step 2, setting an initial value of the distance d between the plane mirror and the front end surface of the nonlinear medium.

[0042] Step 3: Start the system and conduct preliminary testing.

[0043] Step 4, real-time detection of the reflected light V of the OPA main cavity.

[0044] Step 5, generating a voltage control signal according to the reflected light V, and dynamically adjusting the value of the spacing d.

[0045] Step 6: Determine whether the phase matching condition is met.

[0046] Step 7: If the phase matching condition is met, feedback is locked and the power amplified signal IV is output.

[0047] Step 8: If the phase matching condition is not met, return to step 4.

[0048] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0049] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. An active impedance matching phase-sensitive optical amplification system, characterized in that: include: An FP etalon (1), an OPA main cavity (2) and an impedance matching module (3); wherein the FP etalon (1) and the OPA main cavity (2) are arranged on the same optical axis to form an OPA cavity; An impedance matching module (3) is used to frequency modulate the input signal light I to be amplified and output modulated signal light II; The FP etalon (1) is used to send the modulated signal light II and the pump light III into the OPA main cavity (2); The OPA main cavity (2) is used to perform power amplification processing on the modulated signal light II based on the pump light III to obtain a power amplified signal IV and output it; The impedance matching module (3) is also used to generate a voltage control signal according to the reflected light V of the OPA main cavity (2) detected in real time, and dynamically adjust the parameters of the FP standard tool (1) to ensure that the OPA cavity is always in an impedance matching state.

2. The active impedance matching phase sensitive optical amplification system according to claim 1, characterized in that: The OPA main cavity (2) is composed of a nonlinear medium (21) and a plano-concave cavity mirror (22) which are arranged in sequence according to an optical path.

3. The active impedance matching phase sensitive optical amplification system according to claim 2, characterized in that: The FP etalon (1) is composed of a plane reflector (11), a driving element (12) and a front end surface of a nonlinear medium (21); wherein the plane reflector (11) is arranged along the optical path, and the driving element (12) is arranged on the front end surface of the plane reflector (11).

4. The active impedance matching phase sensitive optical amplification system according to claim 3, characterized in that: A signal light input port A and a pump light input port A are provided on the plane reflector (11), a signal light input port B and a pump light input port B are provided on the nonlinear medium (21), and a signal light input port C and a pump light input port C are provided on the plano-concave cavity mirror (22); wherein the modulated signal light II and the pump light III are incident on the FP etalon (1) through the signal light input port A and the pump light input port A respectively, and are output after being acted upon by the FP etalon (1); the modulated signal light II and the pump light III emitted from the FP etalon (1) are incident on the OPA main cavity (2) through the signal light input port B and the pump light input port B respectively, and the relative phases of the modulated signal light II and the pump light III are locked; when the phase matching condition is met, the nonlinear medium (21) generates a pulse having a frequency of ω. s The power amplified signal IV is outputted through the signal light output port C and the pump light output port C respectively.

5. The active impedance matching phase sensitive optical amplification system according to claim 4, characterized in that: When Δk=k p -2k s =0, it is determined that the phase matching condition is met; Otherwise, the phase matching condition is not met; where Δk represents the phase mismatch, k p represents the wave vector of the pump light, k s Represents the wave vector of the signal light.

6. The active impedance matching phase sensitive optical amplification system according to claim 4, characterized in that: Dynamically adjusting the parameters of the FP etalon (1) refers to dynamically adjusting the distance d between the plane reflector (11) and the front end surface of the nonlinear medium (21); wherein the reflectivity R of the FP etalon (1) changes within the range of [0,1] as the distance d changes.

7. The active impedance matching phase sensitive optical amplification system according to claim 6, characterized in that: The impedance matching module (3) comprises: a local oscillator (31), an electro-optic modulator (32), a beam splitter (33), a photodetector (34), a mixer (35), a low-pass filter (36) and a PID controller (37); wherein the electro-optic modulator (32) and the beam splitter (33) are arranged along an optical path; the electro-optic modulator (32) is connected to the mixer (35) via the local oscillator (31); the photodetector (34) is arranged on the reflected optical path of the beam splitter (33); and the output end of the photodetector (34), the mixer (35), the low-pass filter (36) and the PID controller (37) are connected in sequence.

8. The active impedance matching phase sensitive optical amplification system according to claim 7, characterized in that: The signal light I to be amplified is amplitude modulated by an electro-optic modulator (32), and a modulated signal light II is output; The modulated signal light II passes through a beam splitter (33) and together with the pump light III, passes through an FP standard device (1) and is incident on an OPA main cavity (2); the reflected light V of the OPA main cavity (2) passes through a beam splitter (33) and is incident on a photodetector (34); the electrical signal output from the photodetector (34) is mixed with the modulated signal provided by a local oscillator (31) on a mixer (35) to generate an error signal; the high-frequency noise component in the error signal is filtered out by a low-pass filter (36) to obtain a smooth error signal; the smooth error signal is processed by a PID controller (37) to output a voltage control signal, which is loaded onto a driving element (12) to adjust the spacing d.

9. The active impedance matching phase sensitive optical amplification system according to claim 7, characterized in that: There is a phase difference between the modulation signal provided by the local oscillator (31) to the electro-optical modulator (32) and the modulation signal provided by the local oscillator (31) to the mixer (35).

10. The active impedance matching phase sensitive optical amplification system according to claim 3, characterized in that: The front end face of the plane reflector (11), the rear end face of the nonlinear medium (21) and the rear end face of the plano-concave cavity mirror (22) are all coated with anti-reflection films with high transmittance for signal light and pump light; the rear end face of the plane reflector (11) and the front end face of the nonlinear medium (21) are coated with high reflection films with a reflectivity of 99% for signal light; and the front end face of the plano-concave cavity mirror (22) is coated with a high reflection film with a reflectivity of 95% for signal light.

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