CN114628991A - Tunable semiconductor laser driving device - Google Patents

Abstract

The present disclosure provides a tunable semiconductor laser driving device, including: the control module is used for communicating with the upper computer so as to transmit the instruction signal; the current driving circuit is respectively connected with the control module and the semiconductor laser and is used for driving the semiconductor laser to work; the temperature control loop is respectively connected with the control module and the semiconductor laser and is used for controlling the working temperature of the semiconductor laser; the current tuning signal processing circuit is respectively connected with the signal source and the current driving circuit and is used for tuning a signal sent by the signal source and then inputting the signal into the current driving circuit to generate a driving current so as to drive the semiconductor laser to work; and the working state monitoring circuit is used for monitoring the working state of the semiconductor laser and transmitting the state information to the control module.

Description

Tunable semiconductor laser driver

technical field

The present disclosure relates to the technical field of optoelectronic devices and optoelectronic systems, and in particular, to a tunable low-noise semiconductor laser driving device.

Background technique

With the rapid development of semiconductor laser technology, narrow linewidth semiconductor laser modules need to be widely used in the fields of coherent optical communication, fiber sensing and fiber optic gyroscopes. As the light source of the coherent optical communication system, the narrow linewidth semiconductor laser module requires narrow linewidth, low phase noise, and high laser wavelength stability under temperature control conditions. In the field of optical fiber sensing, the requirements for noise and stability of the light source are higher. Therefore, the current semiconductor laser driving devices are difficult to meet the requirements of noise and precise tuning.

SUMMARY OF THE INVENTION

(1) Technical problems to be solved

Based on the above problems, the present disclosure provides a tunable semiconductor laser driving device to alleviate the technical problems that the semiconductor laser driving device in the prior art is difficult to meet the requirements of noise and stability.

(2) Technical solutions

The present disclosure provides a tunable semiconductor laser driving device, comprising:

The control module is used to communicate with the upper computer to transmit the command signal;

A current driving circuit, which is respectively connected with the control module and the semiconductor laser, is used to drive the semiconductor laser to work;

The temperature control loop is connected with the control module and the semiconductor laser respectively, and is used to control the working temperature of the semiconductor laser;

A current tuning signal processing circuit, which is respectively connected with the signal source and the current driving circuit, and is used for tuning the signal sent by the signal source and then inputting the signal into the current driving circuit to generate a driving current so as to drive the semiconductor laser to work; and

The working state monitoring circuit is used to monitor the working state of the semiconductor laser and transmit the state information to the control module.

According to an embodiment of the present disclosure, the command signal includes: a temperature control working point, setting a drive current value, parameters of a working state monitoring circuit, and saving the current working point as a working point set by power-on.

According to the embodiment of the present disclosure, the temperature control is first enabled through the temperature control loop, and then the current is slowly applied until the target driving current value is stabilized.

According to an embodiment of the present disclosure, the control module includes a single-chip microcomputer. After power-on or reset, the single-chip microcomputer first performs system initialization, including setting clock frequency division, setting the door dog, and then reading the semiconductor laser working state set point from the built-in peripheral EEPROM.

According to an embodiment of the present disclosure, the working state set point of the semiconductor laser includes a temperature control working point and a drive current setting value of the semiconductor laser.

According to the embodiment of the present disclosure, the temperature control loop includes two linear power amplifier chips, and the temperature control proportional-integral-derivative parameter setting is realized by combining two operational amplifier logics with resistors and capacitors.

According to the embodiment of the present disclosure, the temperature control loop is respectively connected to both ends of the semiconductor refrigerator through two low-noise power amplifiers, and forms a push-pull structure with two resistors; The partial pressure of the resistance value is processed proportionally; the resistance (R18), resistance (R20), capacitor (C4), capacitor (C6) and another amplifier (U8) form a PID temperature control circuit; The analog converter obtains the temperature control operating point that needs to be set, and then acts on the PID temperature control circuit through a first-order filter composed of a resistor (R19) and a capacitor (C5).

According to an embodiment of the present disclosure, the current driving circuit includes: a tunable current driving circuit based on an adder and a constant current source, or a current driving circuit based on an adder.

According to the embodiment of the present disclosure, the constant current source part of the current drive circuit includes an operational amplifier and a triode; the emitter of the triode is connected to a pull-down precision resistor; the base and the output end of the operational amplifier are connected to a current limiting resistor to ensure the operation of the operational amplifier and the triode In the amplification area; the collector is connected to the negative electrode of the semiconductor laser chip; capacitors are added to the negative electrode and output end of the operational amplifier of the constant current source circuit to effectively suppress high-frequency loop noise.

According to the embodiment of the present disclosure, the working state monitoring circuit selects a multi-channel serial ADC chip.

(3) Beneficial effects

It can be seen from the above technical solutions that the tunable semiconductor laser driving device of the present disclosure has at least one or a part of the following beneficial effects:

(1) The structure of the drive circuit is simple and efficient, which is convenient for PCB board-level integration;

(2) The constant current drive part of the drive circuit has low noise level (≤-120dBm) and high temperature control accuracy (<0.001°C), which can meet the high-precision long-steady-state requirements of the existing optical fiber hydrophone system for the light source;

(3) The drive circuit can meet the low-speed DC tuning of semiconductor lasers under the premise that the noise level and temperature control accuracy are higher than the existing constant current drive, and meet the needs of most optical fiber sensing systems;

(4) The driver can realize the fast tuning of the drive current in the order of MHz, which can meet the requirements of optical phase locking in fiber optic gyroscopes and coherent optical communication;

Description of drawings

FIG. 1 is a schematic diagram of the composition of a tunable semiconductor laser driving device according to an embodiment of the present disclosure.

FIG. 2 is a schematic diagram of a more specific composition of a tunable semiconductor laser driving device according to an embodiment of the disclosure.

FIG. 3 a is a schematic diagram of a main control flow of a tunable semiconductor laser driving device according to an embodiment of the disclosure.

FIG. 3b is a schematic diagram of the sub-control process principle of the tunable semiconductor laser driving device according to the embodiment of the disclosure.

FIG. 4 is a schematic diagram of a current driving circuit based on an adder and an inverse subtractor in a tunable semiconductor laser driving device according to an embodiment of the present disclosure.

5 is a schematic diagram of a current driving circuit based on an adder in a tunable semiconductor laser driving device according to an embodiment of the present disclosure.

6 is a schematic diagram of a temperature control loop in a tunable semiconductor laser driving device according to an embodiment of the present disclosure.

FIG. 7 is a typical diagram of the phase noise power spectrum of the narrow linewidth semiconductor laser under the tunable semiconductor laser driving device according to the embodiment of the present disclosure.

Detailed ways

The present disclosure provides a tunable semiconductor laser drive device, the components of which include a control module based on a C8051/STM32 series single-chip microcomputer, a high-precision temperature control loop based on a power amplifier chip, and a tunable current drive based on an adder and a constant current source. circuit, and a working state monitoring circuit. Compared with the traditional semiconductor laser driver, the driver can meet the functions of low noise and direct current tunability at the same time, and the driver can be used in the fields of coherent optical communication and optical fiber sensing. In addition, based on the inventive concept of the present disclosure, different current tuning schemes can be derived for different application scenarios.

In order to meet the requirements, the semiconductor laser module should have the ability of low-speed current tuning and the low-frequency noise (that is, the noise floor corresponding to the fiber sensing system) should be as low as possible, and there should be no frequency noise peak. As the light source of the fiber optic gyro system, due to the need The phase locking of the two lasers can be performed quickly, and the tunable semiconductor laser driving device of the present disclosure can realize narrow linewidth, low noise and fast tuning.

In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below with reference to the specific embodiments and the accompanying drawings.

In an embodiment of the present disclosure, a tunable semiconductor laser driving device is provided. With reference to FIGS. 1 to 6 , the tunable semiconductor laser driving device includes:

The control module is used to communicate with the upper computer to transmit the command signal;

a current driving circuit, which is respectively connected with the control module and the semiconductor laser, and is used for driving the semiconductor laser to work;

a temperature control loop, respectively connected with the control module and the semiconductor laser, for controlling the working temperature of the semiconductor laser;

a current tuning signal processing circuit, which is respectively connected with the signal source and the current driving circuit, and is used for tuning the signal sent by the signal source and then inputting the signal into the current driving circuit to generate a driving current so as to drive the semiconductor laser to work; and

The working state monitoring circuit is used to monitor the working state of the semiconductor laser and transmit the state information to the control module.

In the embodiment of the present disclosure, the control module is a control module based on the C8051/STM32 series single-chip microcomputer; the present disclosure adopts a solution based on a general-purpose single-chip microcomputer (C8051/STM32, etc.) as the central controller. On the one hand, it communicates with the host computer, and the communication methods are various and can be switched or customized. The different communication protocols with the host computer include UART (RS232 or RS422 level protocol can be used), SPI, IIC, and further, can be adopted General wireless remote control telemetry solutions, such as Bluetooth, infrared communication, etc.; on the other hand, the program running block diagram of the microcontroller is shown in Figure 3a and Figure 3b, after power-on or reset, the microcontroller enters the main control process program (Figure 3a) , first carry out system initialization (including setting clock frequency division, setting open dog), and then read the laser working state set point (including temperature control working point and drive current setting value) from the built-in peripheral EEPROM. Here, the present disclosure adopts the setting of delaying current application, that is, enabling temperature control first, waiting for a period of time, and after the temperature control is stable, then slowly applying current until the target driving current value. On the one hand, this power-on method can greatly prevent the mode jumping of the laser when it is turned on, and on the other hand, it can avoid the damage to the laser chip caused by the instantaneous current pulse when the laser is turned on. After the configuration is complete, the single-chip microcomputer enters the polling state, that is, it has been waiting for the instruction of the upper computer, and then enters the subroutine, of which Figure 3b is the block diagram of the sub-control process. The instructions designed in the present disclosure are divided into four types, namely, setting the temperature control working point, setting the driving current value, uploading the monitored parameters, and saving the current working point as the working point set by the startup.

In the embodiment of the present disclosure, the temperature control loop is a high-precision temperature control loop based on a power amplifier chip; the present disclosure uses two independent linear power amplifier chips of the same type to build a high-precision temperature control loop. The selection of the power amplifier chip can be OPA567, OPA596 or other models with similar functions. The temperature control loop part of the circuit adopts an independent low dropout linear regulator (LDO) to supply power to reduce the influence of power supply noise on the final temperature control accuracy. As shown in Figure 5, U5 and U6 are low-noise power amplifiers, which are connected to both ends of the TEC respectively, and form a push-pull structure with R12 and R13. U7 and U8 are operational amplifiers, among which U7 performs proportional follow-up processing on the partial pressure of the resistance value of the attached thermistor R14; R18, R20, C4, C6 and U8 form a PID temperature control circuit; configure the DAC through the microcontroller to obtain the control that needs to be set. Temperature operating point, and then pass through the first-order filter composed of R19 and C5 to the PID temperature control circuit.

In addition, the present disclosure uses two op-amp logic in combination with resistor-capacitors to implement temperature-controlled proportional-integral-derivative (PID) parameter settings. As shown in Figure 6, the relationship between the PID parameters and the resistance and capacitance values is derived as follows:

Let the instantaneous currents passing through C4, C6 and R18 be i4, i6 and i18 respectively (the default current direction is right);

Due to the virtual short characteristic of the op amp, the voltage of the node us is equal to the set working voltage, which will not affect the calculated PID parameter results, which can be regarded as 0 (ie grounding) here;

From the nodal voltage equations, the following equations can be obtained:

-ui=∫(C4·i4)dt(0.1);

∫(C4·i4)dt=R18·i18 (0.2);

uo=∫(C6·i6)dt+R20·i6 (0.3);

i6=i18+i4(0.4);

Simultaneously combining the above four equations, after eliminating the current parameter, we can get:

积分系数为：

微分系数为：R20·C4；The proportional coefficients can be obtained as:

The integral coefficient is:

The differential coefficient is: R20·C4;

Therefore, the target PID coefficient can be obtained by configuring a specific resistance and capacitance value.

According to an embodiment of the present disclosure, the current driving circuit includes a tunable current driving circuit based on an adder and a constant current source, or a current driving circuit based on an adder.

As shown in Figure 5, a tunable current drive circuit based on an adder and a constant current source is taken as an example to illustrate. The negative feedback constant current source circuit composed of an op amp combined with a triode is used, and a limiter is added to the base of the triode. flow resistance. In order to improve the stability of the circuit and reduce the noise introduced by the circuit, the present disclosure adopts a large-package pull-down precision resistor with low temperature drift (such as a chip resistor with a package size of 1205, a precision of one thousandth, and a temperature drift of 10ppm). In the extreme, passive filtering structures (eg, first-order Chebyshev filtering, pi-type filtering structures, etc.) can be designed. In terms of current tuning, the present disclosure proposes two solutions for different application scenarios. In the aspect of optical fiber hydrophone, it is required to add a 100kHz carrier for current tuning, and it is required not to affect the current operating point of the semiconductor laser when the untuned carrier signal is loaded.

As shown in Figure 4, the forward adder and the reverse subtractor can also be formed by using the characteristics of the operational amplifier to realize the loading of the bipolar signal by the unipolar power supply circuit. In addition, in the aspect of fiber optic gyroscopes, different semiconductor lasers need to be phase-locked, and the realization approach requires fast current tuning of the lasers (tuning bandwidth is on the order of MHz). The above solution cannot meet this requirement, so the present disclosure can also adopt the solution of a direct adder, and the structure is shown in FIG. 5 .

As shown in Figure 4 and Figure 5, on this basis, the emitter of the transistor J2 is connected to a pull-down precision resistor (selected as a high-precision, large-package type resistor; for example, a 1/1000th precision resistor in a 1205 package); the base and the The output end of the operational amplifier is connected to the current limiting resistor R10 to ensure that the operational amplifier and the triode work in the amplification area; the collector is connected to the negative electrode of the laser chip (LD), and a passive filter circuit can be added in the middle to further reduce the LDO power supply noise of the positive electrode of the LD, and at the same time The current tuning bandwidth is also taken into account. In addition, appropriately adding capacitor C2 to the negative electrode and output end of the constant current source operational amplifier U4 can effectively suppress high-frequency loop noise. As shown in FIG. 7 , the optical domain phase noise power spectrum of a semiconductor laser with an intrinsic line width of 10 kHz under the driving device shows that the tunable semiconductor laser driving device of the present disclosure has excellent performance.

In the embodiment of the present disclosure, the working state monitoring circuit includes monitoring the working state of the semiconductor laser and the working state of the temperature-controlled power amplifier chip. The working state monitoring circuit can choose a multi-channel serial ADC chip, such as ADC128S102. The monitoring variables provided by this solution include the voltage division of the constant current source pull-down precision resistor R11, which represents the driving current of the semiconductor laser; the voltage division of the thermistor R14, which represents the The working temperature of the semiconductor laser; the voltage of the backlight detector through the transimpedance amplifier represents the luminous power of the semiconductor laser chip. Among them, the monitoring parameters of the semiconductor laser include the working current (reflected by the pull-down precision resistor divider), the operating temperature of the laser chip (reflected by the thermistor divider value), the luminous intensity of the laser chip (through the current signal of the backlight detector through the The voltage after the transimpedance amplifier circuit is reflected). As for the temperature status of the temperature control power amplifier chip, it is set as the standard by the chip manufacturer.

So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that, in the accompanying drawings or the text of the description, the implementations that are not shown or described are in the form known to those of ordinary skill in the technical field, and are not described in detail. In addition, the above definitions of various elements and methods are not limited to various specific structures, shapes or manners mentioned in the embodiments, and those of ordinary skill in the art can simply modify or replace them.

Based on the above description, those skilled in the art should have a clear understanding of the tunable semiconductor laser driving device of the present disclosure.

能够满足光纤水听、质谱分析和光纤陀螺等领域对光源噪声水平的要求。In summary, the present disclosure provides a tunable semiconductor laser drive device, which includes a control module based on a C8051/STM32 series single-chip microcomputer, a high-precision temperature control loop based on a power amplifier chip, an adder and a constant current source. The tunable current drive circuit, and the working state monitoring circuit. Among them, the single-chip control module can configure a high-precision temperature control loop and a static operating point driven by a current through a 16-bit low-noise DAC. The high-precision temperature control loop is composed of a PID temperature regulation circuit combined with a low-noise power amplifier chip and a semiconductor cooler (TEC) in the laser module. In order to meet the needs of different fields, the tunable current drive circuit part can adopt different schemes. On the one hand, in the field of fiber optic hydrophone, in order to avoid the influence of bipolar modulation signal on the static operating point, a combination of an adder and an inverse subtractor based on a low-noise op-amp chip can be used. On the other hand, in the fiber optic gyroscope, the semiconductor laser current needs to be quickly tuned to realize the phase-locking function, and there is no special requirement for the current bias point. The direct adder method can be used to improve the current tuning bandwidth. In addition, in order to facilitate the monitoring of the working state of the system and subsequent maintenance and repairs, the drive solution also provides a variety of state quantity monitoring, including semiconductor laser operating current, luminous power, light-emitting diode (LD) chip operating temperature and temperature control chip temperature. Wait. In terms of reducing the phase noise and intensity noise of semiconductor laser light emission, this driver not only adds filtering and decoupling circuits in the schematic design, but also avoids the mutual interaction between the temperature control part and the current drive part, the digital part and the analog part in the layout drawing stage. influences. After experimental demonstration, the tunable low-noise semiconductor laser driver provided by the present invention has a low noise level. When driving a semiconductor laser with an intrinsic line width of the order of 10 kHz, it does not affect the line width of the laser light output, and it is in the low frequency range. low level of optical domain phase noise

It can meet the requirements of light source noise level in the fields of fiber optic hydrophone, mass spectrometry and fiber optic gyroscope.

It should also be noted that the directional terms mentioned in the embodiments, such as "up", "down", "front", "rear", "left", "right", etc., only refer to the directions of the drawings, not used to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are denoted by the same or similar reference numbers. Conventional structures or constructions will be omitted when it may lead to obscuring the understanding of the present disclosure. Moreover, the shapes and sizes of the components in the figures do not reflect the actual size and proportion, but merely illustrate the contents of the embodiments of the present disclosure.

The ordinal numbers such as "first", "second", "third", etc. used in the description and the claims are used to modify the corresponding elements, which themselves do not mean that the elements have any ordinal numbers, nor do they Representing the order of a certain element and another element, or the order in the manufacturing method, the use of these ordinal numbers is only used to clearly distinguish an element with a certain name from another element with the same name.

Furthermore, unless the steps are specifically described or must occur sequentially, the order of the above steps is not limited to those listed above, and may be varied or rearranged according to the desired design. And the above embodiments can be mixed and matched with each other or with other embodiments based on the consideration of design and reliability, that is, the technical features in different embodiments can be freely combined to form more embodiments.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above-mentioned specific embodiments are only specific embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure should be included within the protection scope of the present disclosure.

Claims (10)

1. A tunable semiconductor laser driving device comprising:

the control module is used for communicating with the upper computer so as to transmit the instruction signal;

the current driving circuit is respectively connected with the control module and the semiconductor laser and is used for driving the semiconductor laser to work;

the temperature control loop is respectively connected with the control module and the semiconductor laser and is used for controlling the working temperature of the semiconductor laser;

the current tuning signal processing circuit is respectively connected with the signal source and the current driving circuit and is used for tuning a signal sent by the signal source and then inputting the signal into the current driving circuit to generate a driving current so as to drive the semiconductor laser to work; and

and the working state monitoring circuit is used for monitoring the working state of the semiconductor laser and transmitting the state information to the control module.

2. The tunable semiconductor laser driving device according to claim 1, the instruction signal comprising: controlling the temperature of the working point, setting the driving current value, monitoring the parameters of the circuit in the working state, and saving the current working point as the working point set for starting.

3. The tunable semiconductor laser driver of claim 1, wherein the temperature control is performed by a temperature control loop, and the current is ramped up to the target drive current value after stabilization.

4. The tunable semiconductor laser driver of claim 1, wherein the control module comprises a single chip, and after power-on or reset, the single chip performs system initialization, including setting clock division, setting a watchdog, and then reading the semiconductor laser operating state set point from the built-in peripheral EEPROM.

5. The tunable semiconductor laser driving arrangement of claim 2, said semiconductor laser operating condition set points comprising a temperature controlled operating point and a drive current set point for the semiconductor laser.

6. The tunable semiconductor laser driver of claim 1, wherein said temperature control loop comprises two linear power amplifier chips, and the temperature control proportional-integral-derivative parameter setting is implemented by combining two operational amplifier logics with a resistor-capacitor.

7. The tunable semiconductor laser driving device according to claim 6, wherein the temperature control loop is connected to two ends of the semiconductor cooler through two low noise power amplifiers, and forms a push-pull structure with the two resistors; the divided voltage of the resistance value of the attached thermistor (R14) is subjected to proportional following processing through an amplifier (U7); the resistor (R18), the resistor (R20), the capacitor (C4), the capacitor (C6) and the other amplifier (U8) form a PID temperature control circuit; a singlechip in the control module is configured with a digital-to-analog converter to obtain a temperature control working point required to be set, and the temperature control working point acts on the PID temperature control circuit through a first-order filter formed by a resistor (R19) and a capacitor (C5).

8. The tunable semiconductor laser driving device according to claim 1, the current driving circuit comprising: the circuit comprises a tunable current driving circuit based on an adder and a constant current source, or a current driving circuit based on the adder.

9. The tunable semiconductor laser driver of claim 8, wherein said constant current source portion of said current driver circuit comprises an operational amplifier and a transistor; the emitter of the triode is connected with a pull-down precision resistor; the base and the output end of the operational amplifier are connected with a current limiting resistor so as to ensure that the operational amplifier and the triode work in an amplification region; the collector is connected with the cathode of the semiconductor laser chip; and capacitors are added at the negative electrode and the output end of the operational amplifier of the constant current source part circuit so as to effectively inhibit high-frequency loop noise.

10. The tunable semiconductor laser driver of claim 8, wherein said operating condition monitoring circuit is implemented as a multi-channel serial ADC chip.

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