Low-noise high-power ASE light source

Abstract

The invention relates to a low-noise high-power ASE light source which is characterized in that the output end of a pumping source is connected with a first connector of a laser beam combiner, a second connector of the laser beam combiner is connected with one end of a gain optical fiber, and the other end of the gain optical fiber is connected with an anti-reflection astigmatism end; a third joint of the laser beam combiner is connected with a first joint of the optical fiber isolator, a second joint of the optical fiber isolator is connected with an input end of the laser beam splitter, a first output end of the laser beam splitter is connected with an input end of the photodiode, and an output end of the photodiode is connected with an input end of the circuit processing unit; the comprehensive performance of high power, high stability, low noise and wide spectrum is achieved, and the application requirement of the high-precision field is met.

Description

Technical Field

[0001] This invention relates to a low-noise, high-power ASE light source, belonging to the field of laser technology. Background Technology

[0002] Yb³⁺-doped amplified spontaneous emission (ASE) light sources are one of the core research directions in the field of fiber laser technology. Their operating wavelength is mainly concentrated in the near-infrared region of 1.0-1.1 μm, giving them unique advantages in materials processing, medical laser equipment, and space optical communication. Compared with traditional erbium-doped fiber ASE light sources (operating at 1550 nm), ybium-doped ASE light sources have higher quantum efficiency, wider gain bandwidth, and stronger pump absorption capability. The core principle of ASE light sources is that when the gain medium (such as ybium-doped fiber) is pumped and excited, ions in the upper energy level spontaneously emit photons without stimulation. These photons are amplified as they pass through the gain medium, forming a broadband incoherent light output. This type of light source has characteristics such as low coherence and a wide spectrum, playing an irreplaceable role in fiber optic gyroscopes (FOG), optical coherence tomography (OCT), and high-precision spectroscopic measurements.

[0003] The core contradiction facing current technological development is that, with the diversification of application scenarios, comprehensive requirements are put forward for ASE light sources, including higher power density, wider spectral range, better noise performance, and stronger environmental adaptability. Ytterbium-doped light sources are becoming a research hotspot due to their potential in relative intensity noise (RIN) suppression and spectral stability.

[0004] Pump structure design is one of the core factors determining the performance of ASE light sources. Existing technologies have developed a variety of pump architectures to meet the needs of different application scenarios: The bidirectional pumping structure achieves a more uniform population inversion distribution in erbium-doped fiber through the synergistic effect of forward and backward pumping, thereby improving output power and spectral flatness. In ytterbium-doped systems, the main challenge of this technology is the unsaturated effect of ytterbium ion pumping, which causes unabsorbed pump light to damage the opposing pump, requiring precise control of the bidirectional pumping power ratio. Summary of the Invention

[0005] In view of this, the present invention aims to provide a low-noise, high-power ASE light source to solve the problems of high relative intensity noise and insufficient power stability of traditional ASE light sources. It achieves comprehensive performance of "high power, high stability, low noise, and wide spectrum", which is suitable for high-precision application requirements.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows: a low-noise, high-power ASE light source, comprising: a pump source, a laser beam combiner, a gain fiber, an anti-reflection astigmatism end, a fiber isolator, a laser beam splitter, a photodiode, and a circuit processing unit, characterized in that: the output end of the pump source is connected to the first connector of the laser beam combiner; the second connector of the laser beam combiner is connected to one end of the gain fiber; the other end of the gain fiber is connected to the anti-reflection astigmatism end; the third connector of the laser beam combiner is connected to the first connector of the fiber isolator; the second connector of the fiber isolator is connected to the input end of the laser beam splitter; the first output end of the laser beam splitter is connected to the input end of the photodiode; the output end of the photodiode is connected to the input end of the circuit processing unit; the output end of the circuit processing unit is connected to the input end of the pump source; and the second output end of the laser beam splitter is a light output end used to output supercontinuum laser. The pump source outputs a laser pump beam, which is injected into the cladding of the gain fiber by the laser beam combiner. The gain fiber, pumped by the laser beam, generates spontaneous emission light. Part of the spontaneous emission light exits through the anti-reflection astigmatism end, while the other part passes through the laser beam combiner and the fiber isolator in sequence and is incident on the laser beam splitter. The light output from the first output end of the laser beam splitter is converted into a current signal by a photodiode. The circuit processing unit controls the power of the output laser pump beam from the pump source based on the current signal, realizing adaptive adjustment of the pump source. The second output end of the laser beam splitter outputs supercontinuum laser.

[0007] The circuit processing unit includes an inverting amplifier circuit, a composite non-inverting amplifier circuit, and a constant current driving circuit. The output terminal of the inverting amplifier circuit is connected to the input terminal of the composite non-inverting amplifier circuit, the output terminal of the composite non-inverting amplifier circuit is connected to the input terminal of the constant current driving circuit, and the output terminal of the constant current driving circuit is connected to the input terminal of the pump source. The current generated by the photodiode is converted into a voltage signal by an inverting amplifier circuit while simultaneously suppressing noise, outputting a first voltage signal. The composite non-inverting amplifier circuit amplifies the first voltage signal proportionally by adjusting its own adjustable resistor R3. The amplification factor is obtained by the resistance value of the adjustable resistor R3 in the circuit and the grounding resistor R2. When the laser power is low and the light entering the photodiode is weak, the electrical signal is amplified. The adjustable resistor R4 divides the reference voltage Vref to precisely adjust the bias voltage to obtain a suitable static operating point, enabling the operational amplifier A4 to obtain the optimal power supply rejection ratio. The output obtains a second voltage signal that modulates the power of the constant current drive. The second voltage signal enters the constant current drive circuit, causing the constant current drive circuit to change the output laser pump power of the pump source, realizing negative feedback regulation of the output power and improving the stability of the output power.

[0008] The aforementioned inverting amplifier circuit includes a first operational amplifier and a feedback resistor. The non-inverting input terminal of the first operational amplifier is grounded, and the inverting input terminal of the first operational amplifier is connected to the output terminal of a photodiode. The cathode of the photodiode is also connected to one end of the feedback resistor, and the other end of the feedback resistor is connected to the output terminal of the first operational amplifier.

[0009] The composite amplifier circuit includes a second operational amplifier, a third operational amplifier, a fourth operational amplifier, a first adjustable resistor, a second adjustable resistor, a first resistor, a second resistor, a third resistor, and a capacitor. The non-inverting input of the second operational amplifier is connected to the output of the first operational amplifier; the inverting input of the second operational amplifier is connected to the first fixed terminal of the first adjustable resistor; the adjusting terminal of the first adjustable resistor is connected to the output of the second operational amplifier; the inverting input of the second operational amplifier is also connected to one end of the first resistor, and the other end of the first resistor is grounded. The non-inverting input of the third operational amplifier is connected to the output of the second operational amplifier. The inverting input of the third operational amplifier is connected to the power stabilization setpoint. The output of the third operational amplifier is connected to the first fixed terminal of the second adjustable resistor. The adjusting terminal of the second adjustable resistor is connected to the non-inverting input of the fourth operational amplifier. The second fixed terminal of the second adjustable resistor is connected to a reference voltage. The inverting input of the fourth operational amplifier is connected to one end of the second resistor. The other end of the second resistor is connected to one end of a capacitor. The other end of the capacitor is connected to the output of the fourth operational amplifier. The inverting input of the fourth operational amplifier is also connected to one end of the third resistor. The other end of the third resistor is connected to a reference voltage. The output of the fourth operational amplifier is also connected to a constant current drive circuit.

[0010] The power stability setpoint is input from the microcontroller unit to the inverting input of the third operational amplifier. The power stability setpoint is obtained as follows: after the low-noise, high-power ASE light source has been running for 5 minutes, the voltage signal output by the second operational amplifier is first converted from analog to digital using the host computer software, and then continuously sampled for 30 seconds with a refresh rate of 1 second. The average value of all digital display values ​​within 30 seconds is taken as the power stability setpoint.

[0011] The reference voltage is 2.5V.

[0012] The second output end of the laser beam splitter can be in the form of collimated output, bare fiber output, jumper output, or beam expander output.

[0013] The beam splitting ratio of the laser beam splitter is 99:1, 99.9:0.1, or 50:50.

[0014] The gain fiber is a multi-clad fiber, and the length of the gain fiber is inversely proportional to the pump source wavelength.

[0015] The photodiode is a silicon-based diode, a phosphorus-based diode, or an indium gallium arsenide diode.

[0016] Compared with the prior art, the positive effects of the present invention are as follows: (1) is a single-mode output broadband ASE light source. This light source has high power, stable output power and low relative intensity noise. It is based on the spontaneous emission effect of gain fiber to ensure the broadband output characteristics of the light source. In response to the high relative intensity noise that is naturally accompanied by spontaneous emission, a photoelectric feedback mechanism is introduced, and noise is accurately suppressed through a dedicated noise suppression circuit. (2) It does not require custom special devices. Based on commercially available conventional devices, it achieves single-mode output by optimizing three key parameters: pump source wavelength, pump source power, and gain fiber length, and by combining them with optoelectronic feedback noise suppression circuit.

[0017] (3) The output of a supercontinuum laser source with power > 1W, power stability RMS < 0.1%@1W@24h, relative intensity noise RMS < 0.03%@10H-3MHz, and spectral width (3dB) > 15nm has been achieved, and its key performance indicators have achieved quantitative breakthroughs.

[0018] (4) With its core advantages of "high stability, low noise and wide spectrum", this light source is particularly suitable for the field of fiber optic gyroscope (which has strict requirements for light source stability and noise control) and the field of fiber optic passive device testing (which requires wide spectrum coverage to achieve comprehensive testing), and has strong practical applicability. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the low-noise, high-power ASE light source described in the embodiment of the present invention.

[0020] Figure 2 A schematic diagram of the circuit structure of the circuit processing unit described in the embodiment of the present invention.

[0021] Figure 3 A schematic diagram of the relative intensity noise output of the ASE light source described in the embodiment of the present invention.

[0022] Figure 4 A schematic diagram illustrating the stability of the laser power output from the ASE light source described in the embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Pump source; 2. Laser beam combiner; 3. Gain fiber; 4. Anti-reflection scattering end; 5. Fiber optic isolator; 6. Laser beam splitter; 7. Photodiode; 8. Circuit processing unit; 9. Second output terminal; 10. Constant current drive circuit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0026] In the description of this invention, the indicated orientations or positional relationships are based on those shown in the accompanying drawings and are used only for the convenience of describing the invention and for simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] like Figure 1As shown, a low-noise, high-power ASE light source includes: a pump source 1, a laser beam combiner 2, a gain fiber 3, an anti-reflection astigmatism end 4, a fiber isolator 5, a laser beam splitter 6, a photodiode 7, and a circuit processing unit 8. The pump source 1's output is connected to the first connector of the laser beam combiner 2; the laser beam combiner 2's second connector is connected to one end of the gain fiber 3; the gain fiber 3's other end is connected to the anti-reflection astigmatism end 4; the laser beam combiner 2's third connector is connected to the first connector of the fiber isolator 5; the fiber isolator 5's second connector is connected to the input of the laser beam splitter 6; the laser beam splitter 6's first output is connected to the input of the photodiode 7; the photodiode 7's output is connected to the input of the circuit processing unit 8; the circuit processing unit 8's output is connected to the input of the pump source 1; and the laser beam splitter 6's second output 9 is a light output terminal used to output supercontinuum laser light. Pump source 1 outputs a laser pump beam, and laser beam combiner 2 injects the laser pump beam into the cladding of gain fiber 3. Gain fiber 3 is pumped by the laser pump beam and generates spontaneous emission light. Part of the spontaneous emission light exits through anti-reflection astigmatism end 4, and the other part of the spontaneous emission light passes through laser beam combiner 2 and fiber isolator 5 in sequence and is incident on laser beam splitter 6. The light output from the first output end of laser beam splitter 6 is converted into a current signal by photodiode 7. Circuit processing unit 8 controls the power of the output laser pump beam of pump source 1 based on the current signal to realize adaptive adjustment of pump source 1. The second output end 9 of laser beam splitter 6 outputs supercontinuum laser.

[0030] It should be noted that the spontaneous emission principle of the gain fiber 3 is based on the use of photoelectric feedback mechanism to effectively suppress the high relative intensity noise generated by spontaneous emission. Pump source 1 outputs laser light with a wavelength of 900nm-1018nm, such as 915nm@1W (laser wavelength is 915nm, output power is 1W), 976nm@5W, etc., to provide pump energy so that gain fiber 3 can achieve population inversion. When the upper energy level particles are generated, spontaneous emission is generated when the particles transition to the ground state. Laser combiner 2 adopts the form of (1+1)×1, (1+2)×1 or (1+N)×1, and its function is to inject pump light into gain fiber 3 and transmit the spontaneously radiated light in gain fiber 3 to the laser output end through the fiber core. Gain fiber 3 is a multi-clad fiber, including at least double cladding, and can also be triple cladding, quadruple cladding, etc. Its function is to generate spontaneous emission after being pumped and output spontaneously radiated laser light. Anti-reflection astigmatism end 4 has various forms, such as 1) cutting the fiber end face to >7°. 1) Prevent Fresnel reflection by tilting the fiber at an angle that disrupts the perpendicular optical path condition of Fresnel reflection, causing the light that would normally be reflected perpendicularly to deviate from the original optical path. 2) Use a small optical receiver / scatterer with a diameter of <3cm to scatter the light; or use an optical isolator to block the reflected light from entering the optical fiber or light source from the optical path level, further enhancing the anti-reflection effect; 3) Burn the optical fiber into a ball or etch it into a comet tail shape, using the diffuse scattering effect of the non-flat end face to disperse and weaken the reflected light from the end face; 4) Apply anti-reflection coatings to the end cap of the optical fiber and other means to prevent laser reflection. The fiber optic isolator 5 prevents backlighting from the laser output end and the laser beam splitter 6, which could affect the noise of the system stability meter. The beam splitter 6 can have a splitting ratio of 99:1, 99.9:0.1, 50:50, etc., and its function is to split a portion of the laser light for sampling by the photodiode 7. The photodiode 7 can be a silicon-based diode, a phosphorus-based diode, an indium gallium arsenide diode, etc., and its function is to convert the optical signal into a current signal. The output laser signal is then amplified and processed by the circuit processing unit 8 and fed back to the laser pump source 1 to reduce the output noise of the ASE light source and improve the output power stability of the ASE light source.

[0031] like Figure 2 As shown, in some embodiments, the circuit processing unit 8 includes an inverting amplifier circuit, a composite non-inverting amplifier circuit, and a constant current driving circuit 10, wherein the output terminal of the inverting amplifier circuit is connected to the input terminal of the composite non-inverting amplifier circuit, the output terminal of the composite non-inverting amplifier circuit is connected to the input terminal of the constant current driving circuit 10, and the output terminal of the constant current driving circuit 10 is connected to the input terminal of the pump source 1. The current signal generated by photodiode 7 is converted into a voltage signal by the inverting amplifier circuit and noise suppression is achieved at the same time. The composite non-inverting amplifier circuit amplifies the first voltage signal proportionally and adjusts the static operating point of the operational amplifier A4 by adjusting its own adjustable resistor to obtain the second voltage signal. The second voltage signal is used as a constant current drive signal to perform negative feedback regulation on the constant current drive circuit 10, so that the third voltage signal output by the constant current drive circuit 10 can realize the power regulation of the output laser pump beam of the pump source 1.

[0032] In some embodiments, the inverting amplifier circuit includes a first operational amplifier A1 and a feedback resistor R1. The non-inverting input terminal of the first operational amplifier A1 is grounded, and the inverting input terminal of the first operational amplifier A1 is connected to the output terminal of the photodiode 7. The output terminal of the photodiode 7 is also connected to one end of the feedback resistor R1, and the other end of the feedback resistor R1 is connected to the output terminal of the first operational amplifier A1.

[0033] In some embodiments, the composite amplifier circuit includes a second operational amplifier A2, a third operational amplifier A3, a fourth operational amplifier A4, a first adjustable resistor R3, a second adjustable resistor R4, a first resistor R2, a second resistor R5, a third resistor R6, and a capacitor C. The non-inverting input of the second operational amplifier A2 is connected to the output of the first operational amplifier A1; the inverting input of the second operational amplifier A2 is connected to the first fixed terminal of the first adjustable resistor R3; the adjusting terminal of the first adjustable resistor R3 is connected to the output of the second operational amplifier A2; the inverting input of the second operational amplifier A2 is also connected to one end of the first resistor R2; and the other end of the first resistor R2 is grounded. The non-inverting input of the third operational amplifier A3 is connected to the output of the second operational amplifier A2. The inverting input of the third operational amplifier A3 is connected to the power stabilization setpoint. The output of the third operational amplifier A3 is connected to the first fixed terminal of the second adjustable resistor R4. The adjusting terminal of the second adjustable resistor R4 is connected to the non-inverting input of the fourth operational amplifier A4. The second fixed terminal of the second adjustable resistor R4 is connected to the reference voltage VREF. The inverting input of the fourth operational amplifier A4 is connected to one end of the second resistor R5. The other end of the second resistor R5 is connected to one end of the capacitor C. The other end of the capacitor C is connected to the output of the fourth operational amplifier A4. The inverting input of the fourth operational amplifier A4 is also connected to one end of the third resistor R6. The other end of the third resistor R6 is connected to the reference voltage VREF. The output of the fourth operational amplifier A4 is also connected to the constant current drive circuit 10.

[0034] In some embodiments, the power stability setpoint is input from the microcontroller unit (MCU) to the inverting input of the third operational amplifier A3. The power stability setpoint is obtained by: after the low-noise, high-power ASE light source has been running for 5 minutes, the voltage signal output by the second operational amplifier A2 is first converted from analog to digital using the host computer software, and then continuously sampled for 30 seconds with a refresh rate of 1 second. The average value of all digital display values ​​within 30 seconds is taken as the power stability setpoint.

[0035] In some embodiments, the reference voltage VREF is 2.5V.

[0036] It should be noted that the circuit processing unit 8 is used to achieve stable optical feedback power control. The photodiode 7 receives the optical signal and generates a current signal, converting the optical signal into a current signal. This current signal enters the inverting input of the inverting amplifier circuit. The inverting amplifier circuit uses a feedback resistor to convert the current signal into a voltage signal. Simultaneously, it utilizes the low impedance of the inverting input to suppress the interference of input noise current on signal integrity, achieving a high signal-to-noise ratio conversion. The voltage signal enters the composite amplifier circuit. In the composite amplifier circuit, the voltage signal output from the photodiode 7 is input from the non-inverting input of the second operational amplifier A2. In the A2 amplifier circuit, the amplification factor is adjusted using the first adjustable resistor R3. The output of A2 is sent to the non-inverting input of the third operational amplifier A3. A power stabilization point is set by the program and used as a reference potential input to the inverting input of the third operational amplifier A3. Utilizing the differential input virtual short-circuit characteristic of the operational amplifier, a comparator function is achieved. The processed voltage signal is fed into the fourth operational amplifier A4 to generate a constant current drive modulation signal, which is then connected to the constant current drive circuit 10 shunt circuit for negative feedback regulation. In the feedback regulation circuit, the second adjustable resistor R4 is used to adjust the static operating point of the fourth operational amplifier A4 so that the fourth operational amplifier A4 obtains the optimal power supply rejection ratio, thereby realizing the dynamic adjustment of the pump source 1 and iteratively converging the output power of the laser pump source 1 to the preset stable target value.

[0037] In some embodiments, the second output terminal 9 of the laser beam splitter 6 adopts a collimated output, bare fiber output, jumper wire output, or beam expander output form.

[0038] It should be noted that the second output terminal 9 of the laser beam splitter 6 of the present invention is not limited to the above-mentioned cases, but also includes other existing output forms.

[0039] In some embodiments, the beam splitting ratio of the laser beam splitter 6 is 99:1, 99.9:0.1, or 50:50.

[0040] In some embodiments, the gain fiber 3 is a multi-clad fiber, and the length of the gain fiber 3 is inversely proportional to the wavelength of the pump source 1.

[0041] In some embodiments, the photodiode 7 is a silicon-based diode, a phosphorus-based diode, or an indium gallium arsenide diode.

[0042] like Figure 3 As shown, the relative intensity noise RMS value of the ASE light source is 0.028%. Figure 4 As shown, the output power of the ASE light source is 1.07W, and the 24-hour output power stability RMS is <0.1%. This indicates that the ASE light source designed in this invention has low noise and high output power.

[0043] This invention features a simple overall structure and a small number of components, effectively avoiding the self-excitation problem of spontaneous emission light sources caused by reflection from multiple components. This overcomes the limitation of traditional solutions where "single-mode output power is only about 100mW," laying the foundation for power enhancement. The invention employs cladding optical pumping technology, significantly increasing the upper limit of spontaneous emission light output power. Through refined design (such as optimizing pump coupling efficiency and gain medium parameters), the output power is even expected to exceed the 100-watt level, significantly outperforming traditional low-power solutions. This invention integrates a photoelectric feedback mechanism, which can accurately suppress the relative intensity noise (RIN) of the light source, reduce optical signal power fluctuations, and improve the stability of the output light, making it suitable for noise-sensitive applications (such as precision spectral detection and optical communication). This invention optimizes the matching relationship between the length of the gain fiber 3 and the pump wavelength, making the length of the gain fiber 3 inversely proportional to the wavelength of the pump source 1 (for example, if the wavelength of the pump source 1 is 915nm, the length of the gain fiber 3 is 10m, the core diameter of the gain fiber 3 is 10 micrometers, and the cladding light absorption coefficient is 1.0dB / m; different gain fibers 3 have different lengths). This invention can stably achieve ASE (amplified spontaneous emission) light source output in the 1000nm-1120nm band, and its 3dB spectral width is better than 15nm, combining wide band coverage and high spectral purity, thus expanding the application range of the light source.

[0044] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0045] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A low-noise, high-power ASE light source, characterized in that: The system comprises a pump source, a laser beam combiner, a gain fiber, an anti-reflection astigmatism end, a fiber isolator, a laser beam splitter, a photodiode, and a circuit processing unit. Its features include: the output end of the pump source is connected to the first connector of the laser beam combiner; the second connector of the laser beam combiner is connected to one end of the gain fiber; the other end of the gain fiber is connected to the anti-reflection astigmatism end; the third connector of the laser beam combiner is connected to the first connector of the fiber isolator; the second connector of the fiber isolator is connected to the input end of the laser beam splitter; the first output end of the laser beam splitter is connected to the input end of the photodiode; the output end of the photodiode is connected to the input end of the circuit processing unit; the output end of the circuit processing unit is connected to the input end of the pump source; and the second output end of the laser beam splitter is an optical output end used to output supercontinuum laser light. The pump source outputs a laser pump beam, and the laser beam combiner injects the laser pump beam into the cladding of the gain fiber. The gain fiber, pumped by the laser pump beam, generates spontaneous emission light. Part of the spontaneous emission light exits through the anti-reflection astigmatism end, and the other part of the spontaneous emission light passes through the laser beam combiner and the fiber isolator in sequence and is incident on the laser beam splitter. The light output from the first output end of the laser beam splitter is converted into a current signal by a photodiode. The circuit processing unit controls the power of the output laser pump beam of the pump source based on the current signal to achieve adaptive adjustment of the pump source. The second output end of the laser beam splitter outputs supercontinuum laser. The circuit processing unit includes an inverting amplifier circuit, a composite non-inverting amplifier circuit, and a constant current driving circuit. The output terminal of the inverting amplifier circuit is connected to the input terminal of the composite non-inverting amplifier circuit, the output terminal of the composite non-inverting amplifier circuit is connected to the input terminal of the constant current driving circuit, and the output terminal of the constant current driving circuit is connected to the input terminal of the pump source. The current generated by the photodiode is converted into a voltage signal by an inverting amplifier circuit while simultaneously suppressing noise, outputting a first voltage signal. The composite non-inverting amplifier circuit amplifies the first voltage signal proportionally by adjusting its own adjustable resistor. The amplification factor is obtained by the resistance value of the adjustable resistor in the circuit and the grounding resistance. When the laser power is low and the light entering the photodiode is weak, the electrical signal is amplified. The adjustable resistor divides the reference voltage Vref to precisely adjust the bias voltage to obtain a suitable static operating point, enabling the operational amplifier to obtain the optimal power supply rejection ratio. The output obtains a second voltage signal that modulates the power of the constant current drive. The second voltage signal enters the constant current drive circuit, causing the constant current drive circuit to change the output laser pump power of the pump source, achieving negative feedback regulation of the output power and improving the stability of the output power.

2. The low-noise, high-power ASE light source according to claim 1, characterized in that... The aforementioned inverting amplifier circuit includes a first operational amplifier and a feedback resistor. The non-inverting input terminal of the first operational amplifier is grounded, and the inverting input terminal of the first operational amplifier is connected to the output terminal of a photodiode. The cathode of the photodiode is also connected to one end of the feedback resistor, and the other end of the feedback resistor is connected to the output terminal of the first operational amplifier.

3. The low-noise, high-power ASE light source according to claim 1, characterized in that... The composite amplifier circuit includes a second operational amplifier, a third operational amplifier, a fourth operational amplifier, a first adjustable resistor, a second adjustable resistor, a first resistor, a second resistor, a third resistor, and a capacitor. The non-inverting input of the second operational amplifier is connected to the output of the first operational amplifier; the inverting input of the second operational amplifier is connected to the first fixed terminal of the first adjustable resistor; the adjusting terminal of the first adjustable resistor is connected to the output of the second operational amplifier; the inverting input of the second operational amplifier is also connected to one end of the first resistor, and the other end of the first resistor is grounded. The non-inverting input of the third operational amplifier is connected to the output of the second operational amplifier. The inverting input of the third operational amplifier is connected to the power stabilization setpoint. The output of the third operational amplifier is connected to the first fixed terminal of the second adjustable resistor. The adjusting terminal of the second adjustable resistor is connected to the non-inverting input of the fourth operational amplifier. The second fixed terminal of the second adjustable resistor is connected to a reference voltage. The inverting input of the fourth operational amplifier is connected to one end of the second resistor. The other end of the second resistor is connected to one end of a capacitor. The other end of the capacitor is connected to the output of the fourth operational amplifier. The inverting input of the fourth operational amplifier is also connected to one end of the third resistor. The other end of the third resistor is connected to a reference voltage. The output of the fourth operational amplifier is also connected to a constant current drive circuit.

4. The low-noise, high-power ASE light source according to claim 3, characterized in that... The power stability setpoint is input from the microcontroller unit to the inverting input of the third operational amplifier. The power stability setpoint is obtained by: after the low-noise, high-power ASE light source has been running for 5 minutes, the voltage signal output by the second operational amplifier is first converted from analog to digital by the host computer software and then continuously sampled for 30 seconds. The average value of all digital display values ​​within 30 seconds is taken as the power stability setpoint.

5. The low-noise, high-power ASE light source according to claim 3, characterized in that... The reference voltage is 2.5V.

6. The low-noise, high-power ASE light source according to claim 1, characterized in that... The second output end of the laser beam splitter can be in the form of collimated output, bare fiber output, jumper output, or beam expander output.

7. The low-noise, high-power ASE light source according to claim 1, characterized in that... The beam splitting ratio of the laser beam splitter is 99:1, 99.9:0.1, or 50:

50.

8. The low-noise, high-power ASE light source according to claim 1, characterized in that... The gain fiber is a multi-clad fiber, and the length of the gain fiber is inversely proportional to the pump source wavelength.

9. The low-noise, high-power ASE light source according to claim 1, characterized in that... The photodiode is a silicon-based diode, a phosphorus-based diode, or an indium gallium arsenide diode.

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