Tunable current driving device and method for laser

Abstract

The invention relates to the technical field of optical communication, in particular to a tunable current driving device and method for a laser, and the device supplies power to an operational amplifier in a signal processing module through an ultralow-noise positive power supply and an ultralow-noise negative power supply, and directly adjusts the amplitude of a modulation signal from an external signal source. The circuit design is simpler, a multi-stage circuit is not needed to process a modulation signal, the possibility that noise is introduced by the circuit is reduced, meanwhile, bias voltage does not need to be additionally added, an adder does not need to be additionally used, the circuit design is simpler, and integration of a PCB is better facilitated; the current driving module comprises a high-speed operational amplifier and a high-precision resistor, compared with an existing negative feedback constant current source circuit scheme formed by an operational amplifier and a triode or an MOS tube, the negative feedback constant current source circuit does not need to use the triode or the MOS tube, the circuit design is simpler, the driving current precision is higher, and the miniaturization design of the module is more facilitated.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a laser tunable current driving device and method. Background Art

[0002] Since narrow linewidth lasers have ultra-narrow spectral linewidth and ultra-low phase noise, they are widely used in high-precision coherent laser radar, perimeter security, fiber optic hydrophone, fiber optic sensing and coherent optical communication. In the application of laser radar, fiber optic hydrophone and other systems, there are extremely high requirements for the spectral linewidth and phase noise of the laser light source, and the laser is required to have optical frequency modulation function, and a low-frequency modulation signal needs to be applied to the laser, and it is required not to affect the working current of the laser when there is no modulation signal.

[0003] In order to reduce the noise introduced by the circuit, the existing current drive circuit generally adopts the following technical solutions: using the characteristics of operational amplifiers to form a forward adder and a reverse subtractor to achieve the adjustment and loading of bipolar modulation signals by a unipolar power supply circuit, or converting the bipolar modulation signal and the external bias voltage into a unipolar modulation signal through an adder. The current conventional solution for the constant current source circuit of the current drive circuit is a negative feedback circuit constructed by an operational amplifier and a triode. The above solution has a complex circuit design, numerous electronic components, is prone to introduce noise during signal processing, and is not conducive to the miniaturization of module design.

[0004] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in the field of this technology. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to solve the problems in the prior art that the circuit design is complex, noise is easily introduced during the multi-stage circuit processing, and it is not conducive to the miniaturization of module design.

[0006] The present invention adopts the following technical solution:

[0007] In a first aspect, a laser tunable current driving device is provided, comprising: a control module, a signal processing module, a current driving module and a light detector;

[0008] The input end of the signal processing module is connected to an external signal source, and the output end of the signal processing module is connected to one of the input ends of the current driving module; the output end of the control module is connected to the other input end of the current driving module; the output end of the current driving module is connected to the laser; the light detector is used to detect the light signal emitted by the laser, and the light detector is connected to an input end of the control module; wherein the operational amplifier in the signal processing module is powered by a positive power supply and a negative power supply;

[0009] The signal processing module is used to process the amplitude of the modulation signal from the external signal source, and input the processed modulation signal into the current driving module; the control module is used to output the driving voltage according to the detection result of the light detector, and the current driving module is used to generate the driving current according to the processed modulation signal and the driving voltage to drive the laser to work.

[0010] Preferably, the signal processing module comprises an input protection circuit and an amplitude adjustment circuit, the input end of the input protection circuit is used to be connected to the output end of the external signal source, the output end of the input protection circuit is connected to an input end of the amplitude adjustment circuit, and the output end of the amplitude adjustment circuit is connected to the input end of the current driving module;

[0011] The input protection circuit is used to receive a modulation signal from an external signal source and perform overvoltage protection, and the amplitude adjustment circuit is used to process the amplitude of the modulation signal. The processed modulation signal is coupled with the driving voltage and then input into the current driving module.

[0012] Preferably, the input protection circuit includes a resistor R13, a resistor R15, a diode D3 and a diode D4;

[0013] One end of the resistor R15 is grounded, the other end of the resistor R15 is respectively connected to one end of the resistor R13 and an external signal source, and the other end of the resistor R13 is connected to an input end of the amplitude adjustment circuit; the positive electrode of the diode D4 is connected to a negative power supply, the negative electrode of the diode D4 is respectively connected to an input end of the amplitude adjustment circuit and the positive electrode of the diode D3, and the negative electrode of the diode D3 is connected to the positive power supply.

[0014] Preferably, the amplitude adjustment circuit comprises an in-phase amplification unit, an amplitude adjustment unit and an in-phase follower unit;

[0015] The same-direction amplification unit includes an operational amplifier U4, the amplitude adjustment unit includes a resistor R12, a capacitor C12 and an adjustable resistor R14, and the same-direction follower unit includes an operational amplifier U3;

[0016] The other end of the resistor R13 and the cathode of the diode D4 are both connected to the positive input end of the operational amplifier U4; the output end of the operational amplifier U4 is respectively connected to the negative input end of the operational amplifier U4 and one end of the resistor R12, the other end of the resistor R12 is respectively connected to one end of the capacitor C12, one end of the adjustable resistor R14 and the positive input end of the operational amplifier U3, and the other end of the capacitor C12 and the other end of the adjustable resistor R14 are both grounded;

[0017] The output end of the operational amplifier U3 is connected to the reverse input end of the operational amplifier U3 and the input end of the current driving module respectively;

[0018] The power supply end of the operational amplifier U4 is connected to the positive power supply and the negative power supply respectively, and the power supply end of the operational amplifier U3 is connected to the positive power supply and the negative power supply respectively.

[0019] Preferably, it further comprises a filtering module, wherein the filtering module comprises a resistor R5, a diode D1, a capacitor C6 and an operational amplifier U1A;

[0020] One end of the resistor R5 is connected to the control module, and the other end of the resistor R5 is respectively connected to the anode of the diode D1, one end of the capacitor C6 and the positive input end of the operational amplifier U1A;

[0021] The cathode of the diode D1 is connected to one end of the resistor R5 , the other end of the capacitor C6 is grounded, and the output end of the operational amplifier U1A is respectively connected to the reverse input end of the operational amplifier U1A and the input end of the current driving module.

[0022] Preferably, the current driving module includes a coupling unit and an adjustable current source unit;

[0023] The coupling unit includes a resistor R3, a resistor R11, a capacitor C7 and an operational amplifier U1B, and the adjustable current source unit includes an operational amplifier U2, a resistor R1, a resistor R4 and a resistor R6;

[0024] The output end of the operational amplifier U1A is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the positive input end of the operational amplifier U1B;

[0025] The output end of the operational amplifier U3 is connected to one end of the resistor R11, the other end of the resistor R11 is respectively connected to one end of the capacitor C7 and the positive input end of the operational amplifier U1B, and the other end of the capacitor C7 is grounded;

[0026] The output end of the operational amplifier U1B is respectively connected to the inverting input end of the operational amplifier U1B and one end of the resistor R4, and the other end of the resistor R4 is respectively connected to one end of the resistor R1 and the positive input end of the operational amplifier U2;

[0027] The output end of the operational amplifier U2 is connected to the inverting input end of the operational amplifier U2 and one end of the resistor R6 respectively, and the other end of the resistor R1 and the other end of the resistor R6 are both connected to the laser.

[0028] Preferably, the laser is arranged on a semiconductor refrigerator, and the device further comprises a temperature control module, wherein the temperature control module comprises a temperature detection unit, a temperature setting unit, a differential amplification unit and a power amplification unit;

[0029] The temperature detection unit is connected to the other input end of the control module and the first input end of the differential amplifier unit respectively; the input end of the temperature setting unit is connected to the output end of the control module; the output end of the temperature setting unit is connected to the second input end of the differential amplifier unit; the output end of the differential amplifier unit is connected to the input end of the power amplifier unit; and the two output ends of the power amplifier unit are connected to the two ends of the semiconductor refrigerator respectively;

[0030] The temperature detection unit is used to detect the temperature of the laser and generate a feedback voltage, and transmit the feedback voltage to the control module and the differential amplification unit;

[0031] The control module is used to output an analog signal corresponding to the operating temperature of the laser to the temperature setting unit according to the feedback voltage, and the temperature setting unit is used to convert the analog signal corresponding to the operating temperature of the laser into an analog voltage; the differential amplifier unit is used to generate an error voltage according to the feedback voltage and the analog voltage, and the power amplifier unit is used to amplify the error voltage and apply it to both ends of the semiconductor cooler to adjust the temperature of the laser.

[0032] Preferably, the temperature detection unit includes a thermistor RTH1, a resistor R19 and a capacitor C19, the thermistor RTH1 is arranged inside the laser, one end of the thermistor RTH1 is grounded, the other end of the thermistor RTH1 is respectively connected to one end of the resistor R19, one end of the capacitor C19, the first input end of the differential amplifier unit and the control module, the other end of the resistor R19 is connected to a reference voltage, and the other end of the capacitor C19 is grounded;

[0033] The temperature setting unit includes a resistor R22 and a capacitor C20, one end of the resistor R22 is connected to the control module, and the other end of the resistor R22 is respectively connected to one end of the capacitor C20 and the second input end of the differential amplifier unit.

[0034] Preferably, the power amplification unit includes a first power amplification unit and a second power amplification unit, the first power amplification unit includes an operational amplifier U5, and the second power amplification unit includes an operational amplifier U6;

[0035] The reverse input terminal of the operational amplifier U5 is connected to the output terminal of the differential amplifier unit, and the output terminal of the operational amplifier U5 is respectively connected to the positive electrode of the semiconductor refrigerator and the reverse input terminal of the operational amplifier U5;

[0036] The inverting input terminal of the operational amplifier U6 is connected to the output terminal of the differential amplifier unit, and the output terminal of the operational amplifier U6 is respectively connected to the negative electrode of the semiconductor refrigerator and the inverting input terminal of the operational amplifier U6;

[0037] The positive input terminals of the operational amplifier U5 and the operational amplifier U6 are both connected to a reference voltage.

[0038] In a second aspect, a laser tunable current driving method is provided, the method being applicable to the laser tunable current driving device as described in the first aspect, the method comprising:

[0039] The signal processing module processes the amplitude of the modulation signal from the external signal source, and inputs the processed modulation signal into the current driving module;

[0040] The control module outputs a driving voltage according to the detection result of the light detector;

[0041] The current driving module generates a driving current according to the processed modulation signal and the driving voltage to drive the laser to work.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention supplies power to the operational amplifier in the signal processing module through an ultra-low noise positive power supply and a negative power supply, directly adjusts the amplitude of the modulated signal from the external signal source, the circuit design is simpler, and no multi-stage circuit is required to process the modulated signal, thereby reducing the possibility of noise introduced into the circuit. At the same time, no external bias voltage is required, no additional adder is required, the circuit design is simpler, and is more conducive to the integration of the PCB board; the current driving module includes a high-speed operational amplifier and a high-precision resistor. Compared with the existing negative feedback constant current source circuit solution composed of an operational amplifier and a triode or a MOS tube, no triode or a MOS tube is required, the circuit design is simpler, the driving current accuracy is higher, and it is more conducive to the miniaturization design of the module. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 It is a schematic diagram of an existing laser tunable current driving circuit provided by an embodiment of the present invention;

[0046] Figure 2 It is a structural schematic diagram of a laser tunable current driving device provided by an embodiment of the present invention;

[0047] Figure 3 is a structural schematic diagram of a signal processing module and a filtering module provided by an embodiment of the present invention;

[0048] Figure 4 is a specific structural schematic diagram of a laser tunable current driving device provided by an embodiment of the present invention;

[0049] Figure 5 is a structural schematic diagram of a current driving module provided by an embodiment of the present invention;

[0050] Figure 6 is a structural schematic diagram of a temperature control module provided by an embodiment of the present invention;

[0051] Figure 7 It is a flow chart of a laser tunable current driving method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0053] Unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as open inclusion, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "examples", "specific examples" or "some examples" and the like are intended to indicate that specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner, that is, although they may be carried in the embodiments or examples of the above terms due to reasons such as the order and position of appearance, it is not limited to that they can be carried in combination by one embodiment or example.

[0054] In the description of the present invention, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, the meaning of "multiple" is two or more. In addition, for example, the same type of nouns may be described as two independent individuals by adding "A" and "B" at the end. In this case, the corresponding features defined as "A" and "B" are only used to distinguish the same type of individuals for description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features.

[0055] When describing some embodiments, the expressions "coupling", "coupling" and "connection" and their derivatives may be used. For example, when describing some embodiments, the term "connection" may be used to indicate that two or more components are in direct physical or electrical contact with each other. For another example, when describing some embodiments, the term "coupling" may be used to indicate that two or more components are in direct physical or electrical contact. However, the terms "connection" or "coupling" may also refer to two or more components that are not in direct contact with each other, but still cooperate or interact with each other, such as "optical path coupling", "wireless connection", etc. The embodiments disclosed herein are not necessarily limited to the contents of the present invention.

[0056] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0057] Embodiment 1:

[0058] The following writing will be combined with specific circuit examples to explain the content of the scheme. As a person skilled in the art, the circuit in the corresponding figure should not be regarded as the only way to implement the technical solution of the present invention, but the core invention idea of ​​the present invention should be condensed therefrom. The circuit structure within a reasonable range extended on this basis should be regarded as within the protection scope of the present invention. It is worth noting that the components not described in each figure are all referred to the connection structure in the corresponding figure and their own role in the circuit, and will not be repeated in this embodiment.

[0059] Since the laser requires a large drive current (about 150mA) to operate, and the load capacity of general operational amplifiers is relatively weak, such as Figure 1 As shown, the common solution for laser driving circuits is to use an operational amplifier (i.e. Figure 1 U1, U2, U3, U4) and transistors (i.e. Figure 1The negative feedback constant current source circuit is composed of J2) or MOS tube. The function of the triode or MOS tube is to improve the load capacity of the current source circuit. For specific implementation methods, see Figure 1 The circuit design in the above existing solution is relatively complex, with many electronic components, and it is easy to introduce noise during signal processing.

[0060] In order to solve the above problems, this embodiment proposes a laser tunable current driving device, such as Figure 2 As shown, it includes: a control module, a signal processing module, a current driving module and a light detector; the input end of the signal processing module is connected to an external signal source, and the output end of the signal processing module is connected to one of the input ends of the current driving module; the output end of the control module is connected to another input end of the current driving module; the output end of the current driving module is connected to a laser; the light detector is used to detect the light signal emitted by the laser, and the light detector is connected to an input end of the control module; wherein the operational amplifier in the signal processing module is powered by a positive power supply and a negative power supply; the signal processing module is used to process the amplitude of the modulation signal from the external signal source, and input the processed modulation signal to the current driving module; the control module is used to output a driving voltage according to the detection result of the light detector, and the current driving module is used to generate a driving current according to the processed modulation signal and the driving voltage to drive the laser to work.

[0061] In one embodiment, referring to Figure 4 A preamplifier circuit is also provided between the light detector and the control module. The light detector is used to convert a part of the optical signal output by the laser into a voltage signal, and input the corresponding voltage signal to the control module. The preamplifier circuit is used to convert the photocurrent fed back by the light detector into a voltage. According to the detection result of the light detector, the control module outputs a driving voltage to the current driving module to achieve stable output of the optical power of the laser.

[0062] Next, the structure of the laser tunable current driving device will be described in detail.

[0063] In one embodiment, Figure 3As shown, the signal processing module includes an input protection circuit and an amplitude adjustment circuit, the input end of the input protection circuit is used to connect to the output end of the external signal source, the output end of the input protection circuit is connected to an input end of the amplitude adjustment circuit, and the output end of the amplitude adjustment circuit is connected to the input end of the current driving module; the input protection circuit is used to receive the modulation signal from the external signal source and perform overvoltage protection, the amplitude adjustment circuit is used to process the amplitude of the modulation signal, and the processed modulation signal is coupled with the driving voltage and then input into the current driving module.

[0064] In one embodiment, referring to Figure 3 , the input protection circuit includes a resistor R13, a resistor R15, a diode D3 and a diode D4; one end of the resistor R15 is grounded, the other end of the resistor R15 is respectively connected to one end of the resistor R13 and an external signal source, and the other end of the resistor R13 is connected to an input end of the amplitude adjustment circuit; the positive electrode of the diode D4 is connected to a negative power supply, the negative electrode of the diode D4 is respectively connected to an input end of the amplitude adjustment circuit and the positive electrode of the diode D3, and the negative electrode of the diode D3 is connected to the positive power supply. The bipolar low-frequency modulation signal output by the external signal source is input to the input end of the input protection circuit in the signal processing module, which is used to realize overcurrent protection and overvoltage protection for the signal processing module.

[0065] In one embodiment, continue to refer to Figure 3 The amplitude adjustment circuit includes a common-phase amplifier unit, an amplitude adjustment unit and a common-direction follower unit; the common-direction amplifier unit includes an operational amplifier U4, the amplitude adjustment unit includes a resistor R12, a capacitor C12 and an adjustable resistor R14, and the common-direction follower unit includes an operational amplifier U3; the other end of the resistor R13 and the cathode of the diode D4 are both connected to the positive input end of the operational amplifier U4; the output end of the operational amplifier U4 is respectively connected to the reverse input end of the operational amplifier U4 and one end of the resistor R12, the other end of the resistor R12 is respectively connected to one end of the capacitor C12, one end of the adjustable resistor R14 and the positive input end of the operational amplifier U3, and the other end of the capacitor C12 and the other end of the adjustable resistor R14 are both grounded; the output end of the operational amplifier U3 is respectively connected to the reverse input end of the operational amplifier U3 and the input end of the current driving module; the power supply end of the operational amplifier U4 is respectively connected to the positive power supply and the negative power supply, and the power supply end of the operational amplifier U3 is respectively connected to the positive power supply and the negative power supply.

[0066] The in-phase amplifier unit is used to amplify the modulated signal from an external signal source, the amplitude adjustment unit is used to adjust the amplitude of the amplified modulated signal, and at the same time can suppress high-frequency noise in the modulated signal, and the in-phase follower unit is used to realize the impedance transformation function to facilitate the coupling of the low-frequency modulated signal with the DC bias voltage (i.e., the driving voltage).

[0067] In this embodiment, the operational amplifier U3 and the operational amplifier U4 are powered by positive and negative bipolar power supplies, wherein the positive power supply VCC power supply chip can be an ultra-low noise low voltage drop linear regulator, and the negative power supply VEE power supply chip can be a low noise stabilized switched capacitor voltage inverter and a low noise negative voltage regulator, and the cascaded use of the two can suppress power supply noise.

[0068] In order to reduce the influence of the noise in the driving voltage issued by the control module on the laser output, in one embodiment, Figure 3 and Figure 4 As shown, it also includes a filtering module, which includes a resistor R5, a diode D1, a capacitor C6 and an operational amplifier U1A; one end of the resistor R5 is connected to the control module, and the other end of the resistor R5 is respectively connected to the positive electrode of the diode D1, one end of the capacitor C6 and the positive input end of the operational amplifier U1A; the negative electrode of the diode D1 is connected to one end of the resistor R5, the other end of the capacitor C6 is grounded, and the output end of the operational amplifier U1A is respectively connected to the reverse input end of the operational amplifier U1A and the input end of the current driving module. The filtering module is used to filter the driving voltage output by the control module to reduce the high-frequency current noise output by the laser.

[0069] Reference Figure 3 The driving voltage output by the control module is used as the input value VBIAS of the filtering module. The first-order low-pass filter composed of resistor R5, capacitor C6, capacitor C2, capacitor C5 and operational amplifier U1A can suppress the high-frequency noise of the driving voltage VBIAS. The specific values ​​of resistor R5 and capacitor C6 can be designed according to the actual noise frequency range. Diode D1 is used for fast discharge of the driving voltage VBIAS. Capacitor C2 and capacitor C5 are used to decouple the power supply of operational amplifier U1A to ensure that the power supply noise will not be introduced into operational amplifier U1A, thereby reducing the high-frequency current noise output by the laser.

[0070] In this embodiment, the specific value of the driving voltage VBIAS is adjusted by the control module according to the voltage fed back by the preamplifier circuit, and accordingly, the DC current at both ends of the laser can be adjusted in real time according to the actual situation to ensure that the emission power of the laser meets the requirements. At the same time, the use of the filter module to filter the driving voltage VBIAS can greatly reduce the high-frequency noise output by the laser, and can also avoid the problem of laser line width broadening caused by the current drive module.

[0071] Next, the current driving module will be described in detail. In one embodiment, Figure 5 As shown, the current driving module includes a coupling unit and an adjustable current source unit; the coupling unit includes a resistor R3, a resistor R11, a capacitor C7 and an operational amplifier U1B, and the adjustable current source unit includes an operational amplifier U2, a resistor R1, a resistor R4 and a resistor R6.

[0072] The specific connection method is as follows: the output end of the operational amplifier U1A is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the positive input end of the operational amplifier U1B; the output end of the operational amplifier U3 is connected to one end of the resistor R11, and the other end of the resistor R11 is respectively connected to one end of the capacitor C7 and the positive input end of the operational amplifier U1B, and the other end of the capacitor C7 is grounded; the output end of the operational amplifier U1B is respectively connected to the reverse input end of the operational amplifier U1B and one end of the resistor R4, and the other end of the resistor R4 is respectively connected to one end of the resistor R1 and the positive input end of the operational amplifier U2; the output end of the operational amplifier U2 is respectively connected to the reverse input end of the operational amplifier U2 and one end of the resistor R6, and the other end of the resistor R1 and the other end of the resistor R6 are both connected to the laser.

[0073] in, Figure 5 LASER in the figure represents a laser, and the coupling circuit is used to couple the processed modulation signal and the filtered driving voltage to the adjustable current source unit, wherein the capacitor C7 is used to limit the signal noise bandwidth input to the adjustable current source unit, and the specific values ​​of the resistor R3 and the resistor R11 can be selected according to the amplitude of the modulation signal and the driving voltage, and the modulation signal amplitude and the driving voltage input to the adjustable current source unit will change accordingly by adjusting the ratio of the resistor R3 and the resistor R11. The adjustable current source unit is used to receive the driving voltage and the modulation signal, and convert the voltage signal into a current signal and input it into the laser to drive the laser to emit light.

[0074] In this embodiment, the resistance value of the resistor R4 is the same as that of the resistor R7, the resistance value of the resistor R1 is the same as that of the resistor R8, and the current I input to the laser by the adjustable current source unit is LDBIAS Satisfies the following formula:

[0075]

[0076] Wherein, V_LD is the voltage value of the output terminal of the operational amplifier U1B, and R1, R4 and R6 are the resistance values ​​of the resistor R1, the resistor R4 and the resistor R6 respectively.

[0077] Since the laser requires a large operating current (about 150mA), the operational amplifier U2 is a high-speed operational amplifier with a strong load capacity, which can directly output the current required for the laser to work. Among them, capacitors C1 and C4 are used to decouple the power supply VCC of the operational amplifier U2 to ensure that the power supply noise will not be introduced into the operational amplifier U2, reducing the high-frequency current noise output by the laser. The operational amplifier U2 is powered by a positive and negative bipolar power supply, among which the positive power supply VCC power supply chip is an ultra-low noise low-voltage dropout linear regulator, and the negative power supply VEE power supply chip is a low-noise voltage-stabilized switched capacitor voltage inverter and a low-noise negative voltage regulator. The cascaded use of the two can suppress power supply noise.

[0078] In one embodiment, referring to Figure 5 , capacitor C2, resistor R2 and diode D2 form an auxiliary unit to achieve slow start and overvoltage protection functions to ensure the stability of the laser LASER. For more details, see Figure 5 , no further explanation will be given in this embodiment.

[0079] In order to ensure that the emission power of the laser meets the calibrated power, in practical applications, adaptive adjustment is generally performed from two aspects: (1) adjusting the driving current of the laser; (2) adjusting the operating temperature of the laser. The above embodiment has already described the adjustment of the driving current of the laser. Next, the relevant structure and process of adjusting the operating temperature of the laser will be specifically described.

[0080] In one embodiment, Figure 4 and Figure 6As shown, the laser is arranged on a semiconductor refrigerator, and the device also includes a temperature control module, which includes a temperature detection unit, a temperature setting unit, a differential amplifier unit and a power amplifier unit; the temperature detection unit is respectively connected to the other input end of the control module and the first input end of the differential amplifier unit, the input end of the temperature setting unit is connected to the output end of the control module, and the output end of the temperature setting unit is connected to the second input end of the differential amplifier unit; the output end of the differential amplifier unit is connected to the input end of the power amplifier unit, and the two output ends of the power amplifier unit are respectively connected to the two ends of the semiconductor refrigerator.

[0081] The temperature detection unit is used to detect the temperature of the laser and generate a feedback voltage, and transmit the feedback voltage to the control module and the differential amplifier unit; the control module is used to output an analog signal corresponding to the operating temperature of the laser to the temperature setting unit according to the feedback voltage, and the temperature setting unit is used to convert the analog signal corresponding to the operating temperature of the laser into an analog voltage; the differential amplifier unit is used to generate an error voltage according to the feedback voltage and the analog voltage, and the power amplifier unit is used to amplify the error voltage and apply it to both ends of the semiconductor cooler to adjust the temperature of the laser.

[0082] Reference Figure 6 The temperature detection unit includes a thermistor RTH1, a resistor R19 and a capacitor C19. The thermistor RTH1 is arranged inside the laser. One end of the thermistor RTH1 is grounded, and the other end of the thermistor RTH1 is respectively connected to one end of the resistor R19, one end of the capacitor C19, the first input end of the differential amplifier unit and the control module. The other end of the resistor R19 is connected to a reference voltage, and the other end of the capacitor C19 is grounded; the temperature setting unit includes a resistor R22 and a capacitor C20. One end of the resistor R22 is connected to the control module, and the other end of the resistor R22 is respectively connected to one end of the capacitor C20 and the second input end of the differential amplifier unit.

[0083] Wherein, the temperature detection unit is used to convert the temperature of the laser reflected by the thermistor RTH1 inside the laser into a corresponding voltage signal; the temperature setting unit is used to receive the analog signal output by the control module, and convert the analog signal corresponding to the target operating temperature of the laser into an analog voltage VDA and input it into the differential amplifier unit, and the differential amplifier unit is used to amplify the error signal between the feedback voltage VFB corresponding to the laser temperature detected by the temperature detection unit and the analog voltage VDA corresponding to the set target temperature of the laser.

[0084] In one embodiment, Figure 6 As shown, the power amplification unit includes a first power amplification unit and a second power amplification unit, the first power amplification unit includes an operational amplifier U5, and the second power amplification unit includes an operational amplifier U6; the reverse input terminal of the operational amplifier U5 is connected to the output terminal of the differential amplification unit, and the output terminal of the operational amplifier U5 is respectively connected to the positive electrode of the semiconductor refrigerator and the reverse input terminal of the operational amplifier U5; the reverse input terminal of the operational amplifier U6 is connected to the output terminal of the differential amplification unit, and the output terminal of the operational amplifier U6 is respectively connected to the negative electrode of the semiconductor refrigerator and the reverse input terminal of the operational amplifier U6; the positive input terminals of the operational amplifier U5 and the operational amplifier U6 are both connected to the reference voltage (from Figure 6 The reference voltage chip in the circuit is connected.

[0085] The first power amplification unit further includes a resistor R20, a capacitor C17, a resistor R16 and a capacitor C18, and the second power amplification unit further includes a capacitor C21 and a resistor R21. For specific connection methods, see Figure 6 , which will not be described in detail in this embodiment. The two power amplifier units form a bridge series circuit to amplify the error signal output by the differential amplifier unit and apply it to both ends of the semiconductor refrigerator (Thermo Electric Cooler, abbreviated as TEC), and switch the direction of the current flowing through both ends of the TEC through two feedback resistors R17 and resistor R18 to control the heating or cooling of the TEC. Among them, the first power amplifier circuit and the differential amplifier unit form a series PI (Proportion Integral) circuit to achieve accurate and continuous temperature regulation. In actual use, for different TECs, the proportional coefficient and integration time of the PI regulation circuit need to confirm the optimal values ​​of resistor R20, capacitor C17 and resistor R16 according to the required response time range.

[0086] In one embodiment, referring to Figure 6 The temperature control module also includes a current detection amplifier, which is used to convert the current signal flowing through both ends of the TEC into a voltage signal, and input the voltage signal into the control module for monitoring.

[0087] In one embodiment, a temperature control module with high-precision PI regulation is used to achieve closed-loop temperature regulation through a linear analog control method. Within the response time range required for temperature regulation, the integral effect of the control loop is increased as much as possible to prevent laser line spectrum jitter caused by excessively fast temperature regulation. The error between the analog voltage VDA corresponding to the laser set temperature and the feedback voltage VFB corresponding to the laser temperature is amplified, and the current of the TEC is controlled by the error voltage feedback after the error amplification to achieve temperature regulation. This is suitable for temperature control of ultra-low noise laser drive circuits. The error voltage after the error amplification switches the direction of the current flowing through the two ends of the TEC through two feedback resistors to control the heating or cooling of the TEC, thereby achieving precise and continuous temperature regulation of the tunable laser.

[0088] In this embodiment, the control module can adjust the driving current and the operating temperature of the laser respectively through the backlight voltage of the preamplifier circuit and the temperature fed back by the temperature detection unit, so that the emission power of the laser meets the calibrated power in two ways.

[0089] In one embodiment, Figure 4 As shown, the control module includes an analog-to-digital conversion unit, a controller and a digital-to-analog conversion unit connected in sequence; the input end of the analog-to-digital conversion unit is respectively connected to the output end of the light detector and the temperature detection unit; the output end of the digital-to-analog conversion unit is respectively connected to the input end of the current driving module and the input end of the temperature setting unit.

[0090] In one embodiment, in order to improve the accuracy, the analog-to-digital conversion unit can be a 16-bit high-precision analog-to-digital converter (Analog-to-digital converter, abbreviated as ADC), and the digital-to-analog conversion unit can be a 16-bit high-precision digital-to-analog converter (Digital Audio Compress, abbreviated as DAC), and the analog-to-digital conversion unit and the digital-to-analog conversion unit both include multiple input terminals and output terminals to connect different objects respectively.

[0091] In this embodiment, the operational amplifier in the signal processing module is powered by an ultra-low noise positive power supply and a negative power supply, and the amplitude of the modulated signal from the external signal source is directly adjusted. The circuit design is simpler, and there is no need for a multi-stage circuit to process the modulated signal, thereby reducing the possibility of noise introduced into the circuit. At the same time, there is no need for an external bias voltage or an additional adder, so the circuit design is simpler and more conducive to PCB board integration. The current driving module includes a high-speed operational amplifier and a high-precision resistor. Compared with the existing negative feedback constant current source circuit solution composed of an operational amplifier and a triode or a MOS tube, there is no need to use a triode or a MOS tube, the circuit design is simpler, the driving current accuracy is higher, and it is more conducive to module miniaturization design.

[0092] Embodiment 2:

[0093] In the first embodiment, a laser tunable current driving device is proposed. In the present embodiment, a laser tunable current driving method is proposed. Figure 7 As shown, the method includes:

[0094] Step 101: The signal processing module processes the amplitude of the modulation signal from the external signal source, and inputs the processed modulation signal into the current driving module.

[0095] Among them, referring to Example 1, the amplitude adjustment circuit includes a common-phase amplifier unit, an amplitude adjustment unit and a common-phase follower unit. The common-phase amplifier unit is used to amplify the modulation signal, and the amplitude adjustment unit is used to adjust the amplitude of the amplified modulation signal, and at the same time can suppress high-frequency noise in the modulation signal. The common-phase follower unit is used to realize an impedance transformation function, which facilitates the coupling of the low-frequency modulation signal with the DC bias voltage.

[0096] Step 102: The control module outputs a driving voltage according to the detection result of the light detector.

[0097] The preamplifier circuit receives the detection result of the detector, the control module receives the voltage signal from the preamplifier circuit, and according to the monitoring result of the detector, the control module outputs a driving voltage to the current driving module.

[0098] Step 103: The current driving module generates a driving current according to the processed modulation signal and the driving voltage to drive the laser to operate.

[0099] The current driving module includes a coupling unit and an adjustable current source unit. The coupling unit couples the processed modulation signal and the filtered driving voltage to the adjustable current source unit. The adjustable current source unit receives the driving voltage and the modulation signal, converts the voltage signal into a current signal and inputs it into the laser to drive the laser to emit light.

[0100] The specific structure of the laser tunable current driving device is shown in Example 1, and will not be further described in this embodiment.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser tunable current driving device, characterized in that: include: A control module, a signal processing module, a current driving module and a light detector; The input end of the signal processing module is connected to an external signal source, and the output end of the signal processing module is connected to one of the input ends of the current driving module; the output end of the control module is connected to the other input end of the current driving module; the output end of the current driving module is connected to the laser; the light detector is used to detect the light signal emitted by the laser, and the light detector is connected to an input end of the control module; wherein the operational amplifier in the signal processing module is powered by a positive power supply and a negative power supply; The signal processing module is used to process the amplitude of the modulation signal from the external signal source, and input the processed modulation signal into the current driving module; The control module is used to output a driving voltage according to the detection result of the light detector, and the current driving module is used to generate a driving current according to the processed modulation signal and the driving voltage to drive the laser to work.

2. The laser tunable current driving device according to claim 1, characterized in that: The signal processing module includes an input protection circuit and an amplitude adjustment circuit, wherein the input end of the input protection circuit is used to be connected to the output end of the external signal source, the output end of the input protection circuit is connected to an input end of the amplitude adjustment circuit, and the output end of the amplitude adjustment circuit is connected to the input end of the current driving module; The input protection circuit is used to receive a modulation signal from an external signal source and perform overvoltage protection, and the amplitude adjustment circuit is used to process the amplitude of the modulation signal. The processed modulation signal is coupled with the driving voltage and then input into the current driving module.

3. The laser tunable current driving device according to claim 2, characterized in that: The input protection circuit includes a resistor R13, a resistor R15, a diode D3 and a diode D4; One end of the resistor R15 is grounded, the other end of the resistor R15 is respectively connected to one end of the resistor R13 and an external signal source, and the other end of the resistor R13 is connected to an input end of the amplitude adjustment circuit; the positive electrode of the diode D4 is connected to a negative power supply, the negative electrode of the diode D4 is respectively connected to an input end of the amplitude adjustment circuit and the positive electrode of the diode D3, and the negative electrode of the diode D3 is connected to the positive power supply.

4. The laser tunable current driving device according to claim 3, characterized in that: The amplitude adjustment circuit comprises an in-phase amplification unit, an amplitude adjustment unit and an in-phase follower unit; The same-direction amplification unit includes an operational amplifier U4, the amplitude adjustment unit includes a resistor R12, a capacitor C12 and an adjustable resistor R14, and the same-direction follower unit includes an operational amplifier U3; The other end of the resistor R13 and the cathode of the diode D4 are both connected to the positive input end of the operational amplifier U4; the output end of the operational amplifier U4 is respectively connected to the negative input end of the operational amplifier U4 and one end of the resistor R12, the other end of the resistor R12 is respectively connected to one end of the capacitor C12, one end of the adjustable resistor R14 and the positive input end of the operational amplifier U3, and the other end of the capacitor C12 and the other end of the adjustable resistor R14 are both grounded; The output end of the operational amplifier U3 is connected to the reverse input end of the operational amplifier U3 and the input end of the current driving module respectively; The power supply end of the operational amplifier U4 is connected to the positive power supply and the negative power supply respectively, and the power supply end of the operational amplifier U3 is connected to the positive power supply and the negative power supply respectively.

5. The laser tunable current driving device according to claim 4, characterized in that: It also includes a filtering module, which includes a resistor R5, a diode D1 and an operational amplifier U1A; One end of the resistor R5 is connected to the control module, and the other end of the resistor R5 is connected to the anode of the diode D1 and the positive input end of the operational amplifier U1A respectively; The cathode of the diode D1 is connected to one end of the resistor R5 , and the output end of the operational amplifier U1A is connected to the reverse input end of the operational amplifier U1A and the input end of the current driving module respectively.

6. The laser tunable current driving device according to claim 5, characterized in that: The current driving module includes a coupling unit and an adjustable current source unit; The coupling unit includes a resistor R3, a resistor R11 and an operational amplifier U1B, and the adjustable current source unit includes an operational amplifier U2, a resistor R1, a resistor R4 and a resistor R6; The output end of the operational amplifier U1A is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the positive input end of the operational amplifier U1B; The output end of the operational amplifier U3 is connected to one end of the resistor R11, and the other end of the resistor R11 is connected to the positive input end of the operational amplifier U1B; The output end of the operational amplifier U1B is respectively connected to the inverting input end of the operational amplifier U1B and one end of the resistor R4, and the other end of the resistor R4 is respectively connected to one end of the resistor R1 and the positive input end of the operational amplifier U2; The output end of the operational amplifier U2 is connected to the inverting input end of the operational amplifier U2 and one end of the resistor R6 respectively, and the other end of the resistor R1 and the other end of the resistor R6 are both connected to the laser.

7. The laser tunable current driving device according to claim 1, characterized in that: The laser is arranged on a semiconductor refrigerator, and the device further comprises a temperature control module, wherein the temperature control module comprises a temperature detection unit, a temperature setting unit, a differential amplification unit and a power amplification unit; The temperature detection unit is connected to the other input end of the control module and the first input end of the differential amplifier unit respectively; the input end of the temperature setting unit is connected to the output end of the control module; the output end of the temperature setting unit is connected to the second input end of the differential amplifier unit; the output end of the differential amplifier unit is connected to the input end of the power amplifier unit; and the two output ends of the power amplifier unit are connected to the two ends of the semiconductor refrigerator respectively; The temperature detection unit is used to detect the temperature of the laser and generate a feedback voltage, and transmit the feedback voltage to the control module and the differential amplification unit; The control module is used to output an analog signal corresponding to the operating temperature of the laser to the temperature setting unit according to the feedback voltage, and the temperature setting unit is used to convert the analog signal corresponding to the operating temperature of the laser into an analog voltage; the differential amplifier unit is used to generate an error voltage according to the feedback voltage and the analog voltage, and the power amplifier unit is used to amplify the error voltage and apply it to both ends of the semiconductor cooler to adjust the temperature of the laser.

8. The laser tunable current driving device according to claim 7, characterized in that: The temperature detection unit includes a thermistor RTH1 and a resistor R19, wherein the thermistor RTH1 is disposed inside the laser, one end of the thermistor RTH1 is grounded, the other end of the thermistor RTH1 is respectively connected to one end of the resistor R19, the first input end of the differential amplifier unit and the control module, and the other end of the resistor R19 is connected to a reference voltage; The temperature setting unit includes a resistor R22 and a capacitor C20, one end of the resistor R22 is connected to the control module, and the other end of the resistor R22 is respectively connected to one end of the capacitor C20 and the second input end of the differential amplifier unit.

9. The laser tunable current driving device according to claim 7, characterized in that: The power amplification unit includes a first power amplification unit and a second power amplification unit, the first power amplification unit includes an operational amplifier U5, and the second power amplification unit includes an operational amplifier U6; The reverse input terminal of the operational amplifier U5 is connected to the output terminal of the differential amplifier unit, and the output terminal of the operational amplifier U5 is respectively connected to the positive electrode of the semiconductor refrigerator and the reverse input terminal of the operational amplifier U5; The inverting input terminal of the operational amplifier U6 is connected to the output terminal of the differential amplifier unit, and the output terminal of the operational amplifier U6 is respectively connected to the negative electrode of the semiconductor refrigerator and the inverting input terminal of the operational amplifier U6; The positive input terminals of the operational amplifier U5 and the operational amplifier U6 are both connected to a reference voltage.

10. A laser tunable current driving method, characterized in that: The method is applicable to the laser tunable current driving device according to any one of claims 1 to 9, and the method comprises: The signal processing module processes the amplitude of the modulation signal from the external signal source, and inputs the processed modulation signal into the current driving module; The control module outputs a driving voltage according to the detection result of the light detector; The current driving module generates a driving current according to the processed modulation signal and the driving voltage to drive the laser to work.

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