CN219576192U - A frequency-doubled fiber laser and its power stabilization system - Google Patents

Abstract

The utility model relates to the field of fiber lasers, in particular to a frequency doubling fiber laser and a power stabilizing system thereof. The power stabilization system includes: the input end of the optical fiber amplifier is used for being connected with the single-frequency laser; the input end of the waveguide is connected with the output end of the optical fiber amplifier; the input end of the detector is connected with the output end of the waveguide; the optical fiber output end of the pump laser is connected with the optical fiber amplifier; and the input end of the temperature regulating device is connected with the second output end of the controller. The utility model adopts the waveguide mode, thereby not only realizing the power stability rapidly, having fast system response speed and good stabilizing effect, but also improving the accuracy of the output power to the greatest extent.

Description

A frequency-doubled fiber laser and its power stabilization system

technical field

The utility model relates to the field of fiber lasers, in particular to a frequency-doubled fiber laser and a power stabilization system thereof.

Background technique

In recent years, with the development of optical fiber devices, the optical indicators of fiber lasers have been continuously improved, and the degree of integration has become higher and higher, making them irreplaceable in the fields of optical fiber communication, precision measurement, and laser radar.

Since the laser power stability affects the signal-to-noise ratio of the detection signal, the subsequent fiber laser power stability has also become a concern. In the prior art, the electro-optic modulation placed in the output optical path of the laser is generally controlled by photoelectric negative feedback. However, due to the low damage threshold of the modulator, it is not suitable for high-power fiber lasers, and the cost is high, especially for modulators with special bands.

For this reason, it was proposed to use the frequency-doubled light split after the frequency-doubling crystal as the feedback signal of the frequency-doubling crystal temperature to stabilize the power of the frequency-doubling light. Stablize.

Utility model content

In view of the above technical problems, the utility model provides a frequency-doubled fiber laser and its power stabilization system to solve the problem of low adjustment efficiency of the existing fiber laser system.

Based on the above purpose, the utility model provides a power stabilization system for a frequency-doubled fiber laser, including:

Optical fiber amplifier, the input end of the optical fiber amplifier is used to connect the single-frequency laser to receive the fundamental frequency light output by the single-frequency laser, and amplify the optical power of the fundamental frequency light for output;

The waveguide, the input end of the waveguide is connected to the output end of the optical fiber amplifier, which is used to receive the amplified fundamental frequency light and perform frequency multiplication output on the amplified fundamental frequency light, and the waveguide is provided with a temperature adjustment device for adjusting the temperature of the waveguide;

A detector, the input end of the detector is connected to the output end of the waveguide for collecting the laser power after frequency doubling;

A pump laser, the fiber output end of the pump laser is connected to a fiber amplifier to adjust the magnification of the fiber amplifier;

A controller, the input end of the controller is connected to the output end of the detector, and the first output end of the controller is connected to the pump laser, which is used to control the driving current of the pump laser according to the frequency-doubled laser power collected by the detector, and to adjust the temperature The input end of the device is connected to the second output end of the controller.

In addition, the utility model also provides a frequency-doubled fiber laser, including a single-frequency laser and the power stabilization system of the above-mentioned frequency-doubled fiber laser.

Optionally, in the frequency-doubled fiber laser and its power stabilization system, the waveguide is a thin-film lithium niobate ridge waveguide.

Optionally, in the above-mentioned frequency-doubled fiber laser and its power stabilization system, the temperature adjustment device includes a TEC, a TEC drive module and a thermistor, the input of the TEC drive module is connected to the second output terminal of the controller, and the output of the TEC drive module The terminal is connected to the TEC; the thermistor is connected to the controller, and the detected waveguide temperature is sent to the controller.

Optionally, in the frequency-doubled fiber laser and its power stabilization system, the TEC drive module includes MAX1978.

Optionally, the above-mentioned frequency-doubled fiber laser and its power stabilization system also include a beam splitter, the input end of the beam splitter is connected to the output end of the waveguide, and the first output end of the beam splitter is used for power output, beam splitting The second output terminal of the detector is connected to the input terminal of the detector.

Optionally, the frequency-doubled fiber laser and its power stabilization system further include a current driver, the input end of the current driver is connected to the first output end of the controller, and the output end of the current driver is connected to the pump laser.

Optionally, in the frequency-doubled fiber laser and its power stabilization system, the current driver includes an LT3743 chip.

Optionally, in the frequency-doubled fiber laser and its power stabilization system, the controller is an FPGA, the input end of the FPGA is connected to the detector through an ADC, and the first output end of the FPGA is connected to the pump laser through a DAC.

Optionally, the above-mentioned frequency-doubled fiber laser further includes a human-computer interaction system connected to the controller for issuing parameter configuration instructions.

Said scheme has the following beneficial effects:

The frequency-doubled fiber laser and its power stabilization system of the utility model adopt waveguide to realize power stabilization, which has the advantages of simple structure, small volume, low cost, compact structure and high stability, and the waveguide temperature control system can realize waveguide temperature The control with an accuracy of 0.01°C can not only quickly achieve power stabilization, the system responds quickly, and the stabilization effect is good, but also maximizes the accuracy of the output power.

Description of drawings

Fig. 1 is the functional block diagram of the frequency doubling fiber laser in the embodiment of the present invention;

Fig. 2 is the PID compensation circuit diagram of TEC drive module in the utility model embodiment;

Fig. 3 is a connection diagram of the current driver in the embodiment of the present invention.

Implementation

In order to make the technical problems, technical solutions and beneficial effects solved by the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments.

It is to be understood that the embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode of carrying out the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of this disclosure and the appended claims.

It will also be understood that, although the terms first, second etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

It should also be understood that the terms "upper", "lower", "left", "right", "front", "rear", "bottom", "middle", "middle", "top", etc. may be used herein For describing various elements, the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the referred device or element must have a specific oriented, constructed and operative in a specific orientation, and therefore these elements should not be limited by these terms.

These terms are only used to distinguish one element from another. For example, a first element could be termed an "upper" element, and, similarly, a second element could be termed an "upper" element depending on the relative orientation of the elements, without departing from the scope of the present disclosure.

It is further to be understood that the terms "comprises", "comprises", "comprises" and/or "comprises" when used herein specify the presence of stated features, integers, steps, operations, elements and/or components but do not exclude the presence of Or add one or more other characteristics, integers, steps, operations, elements, components and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted to have a meaning consistent with their meaning in the context of this specification and related art, and not to be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In one embodiment, the utility model proposes a frequency doubling fiber laser, as shown in Figure 1, the frequency doubling fiber laser includes: a human-computer interaction system, a single frequency laser (ie, the seed source in Figure 1), and a power Stabilize the system.

The specific structural composition and connection relationship of the frequency-doubled fiber laser are as follows:

The power stabilization system includes fiber amplifiers, waveguides, detectors, pump lasers, and controllers.

The input end of the fiber amplifier is connected to a single-frequency laser to receive the fundamental-frequency light output by the seed source, and amplify and output the optical power of the fundamental-frequency light; the seed source is a single-frequency semiconductor light source or a single-frequency light source built by a fiber laser cavity, used for Provide the fundamental frequency light of the frequency-doubled fiber laser, and realize the tuning of the output light source wavelength of the seed source by controlling the operating temperature and operating current of the seed source.

The waveguide adopts a thin-film lithium niobate ridge waveguide, that is, a PPLN waveguide. The input end of the PPLN waveguide is connected to the output end of the fiber amplifier, which is used to receive the amplified fundamental frequency light and output the amplified fundamental frequency light. The stability of optical power must meet: the PPLN waveguide works in the linear region of conversion efficiency. The PPLN waveguide is a nonlinear optical fiber device for frequency conversion, and it is also the core optical device of the system. Through high-precision temperature control and temperature adjustment, the frequency-doubled optical output with maximum efficiency is realized. The main operating parameters of the PPLN waveguide are directly related to the temperature. Therefore, stable temperature control is required for the PPLN waveguide to work stably. For this reason, the PPLN waveguide is equipped with a temperature adjustment device for adjusting the temperature of the waveguide; the temperature adjustment device includes TEC, TEC drive Module and thermistor, the input end of the TEC drive module is connected to the second output end of the controller, and the output end of the TEC drive module is connected to the TEC; the thermistor is connected to the controller, and the detected waveguide temperature is sent to the controller. This implementation The TEC drive module in the example includes MAX1978 chip, which controls the TEC drive module through the external proportional integral differential (PID) compensation network as shown in Figure 2. The temperature control accuracy can reach 0.001°C. After the whole system works stably, the system accuracy can meet 0.01°C requirement.

The detector is a photodetector, and the input end of the detector is connected to the output end of the PPLN waveguide through a beam splitter (the beam splitter is a fiber optic beam splitter) to collect the laser power after frequency doubling; the input end of the beam splitter is connected to The output end of the waveguide and the first output end of the beam splitter are used for power output, and the second output end of the beam splitter is connected to the input end of the detector.

Pump laser, the fiber output end of the pump laser is connected to the fiber amplifier to adjust the amplification factor of the fiber amplifier; specifically, the pump laser provides a pump light source for the gain medium used in the fiber amplifier, and the seed is realized by adjusting the working current of the pump laser. The multiple of source light power amplification.

The controller adopts FPGA, the input terminal of FPGA is connected to the detector through ADC, and the first output terminal of FPGA is connected to the pump laser through DAC and current driver, which is used to control the pumping laser according to the frequency-doubled laser power collected by the detector. Drive current; the second output of the FPGA is connected to the input of the TEC drive module through the DAC to adjust the temperature of the waveguide; the third output of the FPGA is connected to the input of the seed source through the DAC to control the parameters of the seed source. The FPGA communicates with the human-computer interaction system to receive instructions issued by the human-computer interaction system.

The current driver includes the LT3743 chip. The LT3743 chip is used to achieve 10A level current drive. The connection relationship is shown in Figure 3. The DAC is connected to the pump laser through the LT3743. The LT3743 is a synchronous step-down DC/DC controller. It uses Fixed frequency, uniform current mode control to precisely regulate inductor current through a sense resistor in series with the inductor. The LT3743 can regulate current in the load with ±6% accuracy, and its switched capacitor topology also reduces board size by using a compact low value inductor. Of course, on the basis of realizing stable power control, the current driver may not be provided.

The ADC is a high-speed ADC, and the DAC is a high-speed DAC. The high-speed ADC/DAC is an important part of power stability control. In this embodiment, a high-precision high-speed chip is used to realize analog-to-digital conversion. Specifically: the ADC uses a 16-bit 2Mhz differential ADC sampling chip. The differential signal input can minimize the interference of power supply ripple and external noise on the PD sampling signal. At the same time, high sampling bits can ensure PD sampling accuracy, while high data processing The speed can minimize the reaction time of the system, thereby increasing the stabilization effect of the power. The DAC uses a single-ended 16-bit 2Mhz chip to control the current of the LT3743.

The working steps of the power stabilization system are as follows:

1) The human-computer interaction system issues the temperature and current of the seed source, and the current command of the pump laser, and the FPGA performs parameter configuration to control the seed source and the pump laser to work according to the command.

2) The power of the seed source is amplified through the optical fiber amplifier, and the amplified fundamental frequency light enters the PPLN waveguide. At the same time, the human-computer interaction system issues the parameter command of the TEC drive module, and the FPGA maximizes the output frequency-multiplied optical power by adjusting the operating temperature of the PPLN waveguide.

3) The beam splitter divides the frequency-doubled light output by the PPLN waveguide into two paths, one path enters the photodetector as a reference signal for power feedback, and the other path acts as a laser output. The power of the two beams after passing through the beam splitter is linear, so only It is necessary to ensure the stability of the beam power of the feedback path to achieve the stability of the output beam power.

4) When the working state of the PPLN ridge waveguide is stable, turn on the power stabilization mode, and the FPGA will collect the output light intensity of the system through the photodetector/ADC, compare it with the system setting value through calculation, and run the PID algorithm in the FPGA to quickly calculate The adjustment amount is output, and the current of the pump laser is controlled to change towards the set value through the DAC, so as to finally realize the stable control of the power. The working current of the pump laser has a linear relationship with the output power of the fiber amplifier, and the system has a fast response speed and a good stabilization effect.

FPGA is a programmable logic device, which has abundant hardware resources and can realize powerful logic functions. Due to the characteristics of its hardware reconstruction, it is suitable for applications in various fields; this embodiment adopts high-performance FPGA, which can realize high processing Speed, the built-in IP core can realize addition, subtraction, multiplication, and division operations in one cycle, so FPGA running PID algorithm processing has inherent stability and processing speed advantages compared to MCU.

The FPGA controls and configures the pump laser current according to the PID algorithm to realize the control of the drive current of the pump laser, and the final result is to obtain a stable output laser power. In view of the concurrency of high-performance FPGA work and its ability to sample a very high working cycle, such as 100Mhz, at the same time, internal multiplication and addition and subtraction all use high-speed IP cores, which can complete calculations within one working cycle to ensure the timeliness of the PID algorithm It is very high, and a high-speed ADC/DAC chip is used, which reduces the data conversion delay time, and finally ensures that this solution can get a very good stability index.

Regarding the waveguide, detector, temperature adjustment device, controller, etc., which are relatively mature equipment in the prior art, the specific implementation methods mentioned above are not limited in the present invention, as long as the corresponding functions can be realized.

The utility model adopts the waveguide method to realize power stability, and has the advantages of simple structure, small size, low cost, compact structure and high stability, and the high-precision temperature control system of the waveguide can realize the control of the waveguide temperature accuracy of 0.01°C, not only Power stabilization can be achieved quickly, the system responds quickly, the stabilization effect is good, and the accuracy of output power is maximized.

The above-described embodiments are only used to illustrate the technical solutions of the present utility model, and are not intended to limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still understand the foregoing The technical solutions recorded in each embodiment are modified, or some of the technical features are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present utility model, and all Should be included in the scope of protection of the present utility model.

Claims (10)

1. A power stabilization system for a frequency doubled fiber laser, comprising:

the input end of the optical fiber amplifier is used for being connected with the single-frequency laser so as to receive the fundamental frequency light output by the single-frequency laser and amplify and output the optical power of the fundamental frequency light;

the input end of the waveguide is connected with the output end of the optical fiber amplifier and is used for receiving the amplified fundamental frequency light and performing frequency multiplication output on the amplified fundamental frequency light, and the waveguide is provided with a temperature regulating device for regulating the temperature of the waveguide;

the input end of the detector is connected with the output end of the waveguide and is used for collecting the laser power after frequency multiplication;

the optical fiber output end of the pump laser is connected with the optical fiber amplifier, and the amplification factor of the optical fiber amplifier is adjusted;

and the input end of the temperature regulating device is connected with the second output end of the controller.

2. The power stabilization system of a frequency doubled fiber laser of claim 1 wherein the waveguide is a thin film lithium niobate ridge waveguide.

3. The power stabilization system of a frequency doubling fiber laser according to claim 1 or 2, wherein the temperature adjusting device comprises a TEC, a TEC driving module and a thermistor, an input end of the TEC driving module is connected with a second output end of the controller, and an output end of the TEC driving module is connected with the TEC; the thermistor is connected with the controller and sends the detected waveguide temperature to the controller.

4. The power stabilization system of a frequency doubled fiber laser of claim 3 wherein TEC drive module comprises MAX1978.

5. The power stabilization system of a frequency doubled fiber laser of claim 1 further comprising a beam splitter, an input of the beam splitter connected to an output of the waveguide, a first output of the beam splitter for power output, and a second output of the beam splitter connected to an input of the detector.

6. The power stabilization system of a frequency doubled fiber laser of claim 1 further comprising a current driver having an input coupled to the first output of the controller and an output coupled to the pump laser.

7. The power stabilization system of a frequency doubled fiber laser of claim 6 wherein the current driver comprises an LT3743 chip.

8. The power stabilization system of frequency doubling fiber laser of claim 1, wherein the controller is an FPGA, an input of the FPGA is connected to the detector through an ADC, and a first output of the FPGA is connected to the pump laser through a DAC.

9. A frequency doubled fiber laser comprising a single frequency laser, further comprising a power stabilization system for the frequency doubled fiber laser of any of claims 1-8.

10. The frequency doubling fiber laser of claim 9, further comprising a human-machine interaction system connected to the controller for issuing parameter configuration instructions.