A driving circuit of a tunable laser and a tunable laser

Abstract

The application discloses a driving circuit of a tunable laser and the tunable laser, and belongs to the technical field of laser driving circuits.The driving circuit of the tunable laser comprises a signal control module, a voltage follower module, a switch signal conversion module, a signal superposition module and a voltage-controlled current source module; the signal control module is connected with the input ends of the voltage follower module and the switch signal conversion module; the signal superposition module is connected with the output ends of the voltage follower module and the switch signal conversion module; the output end of the signal superposition module is connected with the input end of the voltage-controlled current source module, and the output end of the voltage-controlled current source module acts on the tunable laser; and the output signal of the voltage follower module and the output signal of the switch signal conversion module are converted into the working current of the tunable laser through the signal superposition module and the voltage-controlled current source module, so that the tunable and stable working current is provided for the multi-wavelength array laser, and the quick and stable switching of the wavelength of the tunable laser is realized.

Description

Technical Field

[0001] This invention belongs to the technical field of optoelectronic communication, specifically relating to a driving circuit for a tunable laser and a tunable laser. Background Technology

[0002] The demands on data centers are undergoing a dramatic transformation. The rise of emerging technologies such as cloud computing, big data, and artificial intelligence has led to a surge in global data volume. Traditional electrical signal switching networks are struggling to meet this challenge, as they face the dual challenges of bandwidth and energy consumption. Against this backdrop, all-optical switching technology has emerged. This technology eliminates the need for photoelectric signal conversion at switching nodes, offering numerous advantages such as high bandwidth, low power consumption, and low latency, and is therefore considered the mainstream switching architecture for future data centers.

[0003] In all-optical switching technology, tunable lasers are crucial components. Their wavelength accuracy and switching speed are critical to the overall system performance. Tunable laser chips based on multi-wavelength series-parallel DFB semiconductor laser arrays achieve rapid wavelength tuning by alternately turning different channels of the tunable laser chip on / off through multiple drive current sources. For all-optical switching systems, the routing between any wavelengths is completely random and determined by the user. This means that the laser turn-on and turn-off times of each wavelength channel of the tunable laser are random, and the switching between any channel at any operating time must be possible. The wavelength reconstruction time is expected to be on the order of nanoseconds. In addition, although the laser array in the tunable laser chip will not be lit simultaneously, the operating current required for each channel to turn on will be different. Furthermore, when not lit, a certain bias current (below the laser threshold) still needs to be provided to ensure that the wavelength of the working channel can be emitted smoothly when other channels connected in series are working, while reducing the impact of relaxation oscillation and improving the tuning speed. Therefore, the driving circuit of this tunable laser chip needs to provide a driving current source for each channel. The current magnitude of each current source in the on and off states is adjustable, and the switching time between states is on the order of nanoseconds. After switching, the driving circuit must maintain a stable output current value in both on and off states to ensure the working performance of the laser.

[0004] However, current commercial laser driver chips are mainly geared towards data modulation applications, with limited current driving capability and tuning flexibility, and a small range of current stability time. This makes it difficult to meet the requirements of high-speed tunable lasers such as random wavelength switching and arbitrary adjustment of channel operating time. While high-speed DACs, RF amplifiers, and transistors can achieve the relevant functions, they require a high number of high-speed control interfaces, resulting in high implementation costs and high power consumption. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a driving circuit and a tunable laser that can provide a controllable and stable operating current for a multi-wavelength array laser, while achieving fast and stable switching.

[0006] This invention provides the following technical solution:

[0007] In one aspect, a driving circuit for a tunable laser is provided, including a signal control module, a voltage follower module, a switching signal conversion module, a signal superposition module, and a voltage-controlled current source module;

[0008] The signal control module is connected to the input terminals of the voltage follower module and the switch signal conversion module, respectively; the signal superposition module is connected to the output terminals of the voltage follower module and the switch signal conversion module, respectively; the output terminal of the signal superposition module is connected to the input terminal of the voltage-controlled current source module.

[0009] The signal control module is used to provide bias current control signal, amplitude control signal and high-speed switching control signal; the bias current control signal is generated by a first low-speed digital-to-analog converter, the amplitude control signal is generated by a second low-speed digital-to-analog converter, and the high-speed switching control signal is generated by an FPGA unit;

[0010] The voltage follower module is used to buffer the bias current control signal and generate a buffered bias current control signal.

[0011] The switching signal conversion module is used to convert the high-speed switching control signal and the amplitude control signal into an amplitude-controllable output switching control signal;

[0012] The signal superposition module is used to add the output switch control signal and the buffer bias current control signal, and output the superimposed voltage signal.

[0013] The voltage-controlled current source module is used to convert the superimposed voltage signal into a current signal in order to provide operating current for the multi-wavelength array laser module.

[0014] Preferably, both the first low-speed digital-to-analog converter and the second low-speed digital-to-analog converter are controlled by the FPGA unit in the signal control module; the reference voltage used by the switching signal conversion module is output through the signal control module.

[0015] Preferably, the voltage follower module includes a first operational amplifier, resistors R5 and R6, and capacitors C1 and C2. The non-inverting input of the first operational amplifier is connected to a first low-speed digital-to-analog converter through resistor R5 and grounded through capacitor C1. The inverting input of the first operational amplifier is connected to the output through resistor R6 and is connected in parallel across resistor R6 through capacitor C2. The output of the first operational amplifier is connected to a signal superposition module.

[0016] Preferably, the switching signal conversion module includes a dual-gate N-channel MOSFET, a VCC DC voltage source, and resistors R1, R2, R3, and R4. The first gate of the dual-gate N-channel MOSFET is connected to a second low-speed digital-to-analog converter through resistor R4, the second gate is connected to the output terminal of the FPGA unit through resistor R3, and is connected to the reference voltage output terminal through resistor R2. The first drain of the dual-gate N-channel MOSFET is connected to the signal superposition module, and the second drain is connected to the VCC DC voltage source through resistor R1. The source of the dual-gate N-channel MOSFET is connected to signal ground.

[0017] Preferably, when the high-speed switching control signal generated by the FPGA unit is low, the output voltage of the switching signal conversion module is V. 幅值开关 :

[0018] V 幅值开关 =VCC

[0019] Wherein, VCC is the voltage of the DC voltage source connected to the drain of the dual-gate N-channel MOS transistor;

[0020] When the high-speed switching control signal generated by the FPGA unit is high, the output voltage of the switching signal conversion module is V. 幅值开关 :

[0021] V 幅值开关 =VCC-k·(V 幅值 -V th )·R1

[0022] Where VCC is the voltage of the DC voltage source connected to the drain of the dual-gate N-channel MOSFET; k is a correction factor, V 幅值 V is the amplitude control signal output by the second low-speed digital-to-analog converter. th R1 is the threshold turn-on voltage of the dual-gate N-channel MOSFET, and R1 is the resistance value of resistor R1.

[0023] Preferably, the signal superposition module includes a second operational amplifier, resistors R7, R8 and R9, and capacitor C3. The non-inverting input of the second operational amplifier is connected to the voltage follower module through R7, and the output is connected to the voltage-controlled current source module. The inverting input is connected to the output of the second operational amplifier through resistor R8 and to the switching signal conversion module through resistor R9. Capacitor C3 is connected in parallel across resistor R8.

[0024] Preferably, the resistance values ​​of resistors R8 and R9 are equal, and the output voltage V of the second operational amplifier is... 差分输出 for:

[0025] V 差分输出 =2·V 跟随输出 -V 幅值开关

[0026] Among them, V 幅值开关 V is the output voltage of the switch signal conversion module. 跟随输出 This is the output voltage of the voltage follower module.

[0027] Preferably, the voltage-controlled current source module includes a third operational amplifier, a fourth operational amplifier, an NPN transistor, resistors R10, R11, R12, R13, R14, R15, R16, R17, R18 and R19, and a capacitor C4.

[0028] The non-inverting input of the third operational amplifier is connected to the output of the signal superposition module through resistor R10, and the output of the third operational amplifier is connected to the base of the NPN transistor through resistor R11; the first path of the inverting input of the third operational amplifier is connected to the output of the third operational amplifier through capacitor C4, and the second path of the inverting input is connected to resistor R19.

[0029] The collector of the NPN transistor is connected to a DC voltage source through resistor R12; the emitter of the NPN transistor is connected to a multi-wavelength laser array module through resistors R13 and R14.

[0030] One end of resistor R14 is connected to the non-inverting input of the fourth operational amplifier through R16. The non-inverting input of the fourth operational amplifier is grounded through resistor R17. The output of the third amplifier is connected to resistor R19 and connected to the other end of resistor R14 through resistors R18 and R15. The inverting input of the fourth operational amplifier is connected to resistor R15.

[0031] Preferably, the resistance values ​​of resistors R15, R16, R17, and R18 are equal, and the operating current of the multi-wavelength laser array module is I. 工作电流 :

[0032]

[0033] Among them, V 差分输出 R14 is the output voltage of the second operational amplifier, and R14 is the resistance value of resistor R14.

[0034] In a second aspect, a tunable laser is provided, employing a driving circuit for the tunable laser described in any one of the first aspects.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. This invention uses a high-speed switching control signal generated by an FPGA unit and an amplitude control signal from a second low-speed digital-to-analog converter DAC2 to jointly change the drain current of a dual-gate N-channel MOSFET, thereby changing the voltage across resistor R1, and thus controlling the signal V output by the switching signal conversion module, which has amplitude and switching characteristics. 幅值开关 A signal V with amplitude and switching. 幅值开关 The bias current control signal, buffered by the voltage follower module, is converted into the operating current I of the adjustable laser through the signal superposition module and the voltage-controlled current source module. 工作电流 This enables the provision of controllable and stable operating current for multi-wavelength array lasers, as well as the rapid and stable switching of tunable laser wavelengths.

[0037] 2. This invention uses a bias current control signal emitted by a first low-speed digital-to-analog converter DAC1. This bias current control signal, after passing through a voltage follower module, a signal superposition module, and a voltage-controlled current source module, provides a precisely adjustable operating current to the multi-wavelength laser array module. When the laser is in the off state, the operating current output by the voltage-controlled current source module is the bias current of the laser. The purpose of providing bias current to the laser module is to ensure that the laser is in the excited state and ready to emit a laser beam, thereby effectively reducing the time required for the laser output power to reach a stable state. Adjusting the operating current can help to quickly switch the wavelength or frequency of the laser, reducing the channel switching time. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the overall structure of the tunable laser driving circuit of the present invention;

[0039] Figure 2 This is a schematic diagram showing the relationship trend of the main parameters in the dual-gate N-channel MOS transistor of the present invention.

[0040] The diagram is labeled as follows: 100 is the signal control module, 200 is the voltage follower module, 300 is the switch signal conversion module, 400 is the signal superposition module, and 500 is the voltage-controlled current source module. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0042] In one embodiment, such as Figure 1 As shown, a driving circuit for an adjustable laser is provided, including a signal control module 100, a voltage follower module 200, a switch signal conversion module 300, a signal superposition module 400, and a voltage-controlled current source module 500.

[0043] The signal control module 100 is connected to the input terminals of the voltage follower module 200 and the switch signal conversion module 300, respectively; the signal superposition module 400 is connected to the output terminals of the voltage follower module 200 and the switch signal conversion module 300, respectively; the output terminal of the signal superposition module 400 is connected to the input terminal of the voltage-controlled current source module 500, and the output terminal of the voltage-controlled current source module 500 is connected to the multi-wavelength laser array module.

[0044] The signal control module 100 is used to provide a bias current control signal, an amplitude control signal, and a high-speed switching control signal; the bias current control signal is generated by a first low-speed digital-to-analog converter DAC1, the amplitude control signal is generated by a second low-speed digital-to-analog converter DAC2, and the high-speed switching control signal is generated by an FPGA unit; the signal control module 100 also outputs a reference voltage for use by the switching signal conversion module 300.

[0045] By setting the first low-speed digital-to-analog converter DAC1, a bias current is provided for the multi-wavelength laser, thereby ensuring that the multi-wavelength laser is in an excited state and ready to emit a laser beam. This reduces the time it takes for the output power of the multi-wavelength laser to reach a stable state. Adjusting the bias current can help to quickly switch the wavelength or frequency of the laser and reduce the channel switching time.

[0046] The voltage follower module 200 is used to buffer the bias current control signal and generate a buffered bias current control signal.

[0047] Specifically, the voltage follower module 200 includes a first operational amplifier, resistors R5 and R6, and capacitors C1 and C2; one end of resistor R5 is connected to the first low-speed digital-to-analog converter DAC1, and the other end is connected to capacitor C1 and the non-inverting input terminal of the first operational amplifier A1; one end of resistor R6 is connected to the inverting input terminal of operational amplifier A1, and the other end is connected to resistor R7 in the signal superposition module 400 and the output terminal of the first operational amplifier A1; both ends of capacitor C1 are connected to the non-inverting input terminal of the first operational amplifier A1 and signal ground (GND) respectively; one end of resistor C2 is connected to the inverting input terminal of operational amplifier A1, and the other end is connected to resistor R7 in the signal superposition module 400 and the output terminal of the first operational amplifier A1.

[0048] In the voltage follower module 200, the output voltage of the first operational amplifier A1 is V. 跟随输出 ,

[0049] V 跟随输出 =V 偏置电流 (1)

[0050] Among them, V 偏置电流 This is the bias current control signal generated by the first low-speed digital-to-analog converter DAC1.

[0051] The switching signal conversion module 300 is used to convert the high-speed switching control signal and the amplitude control signal into an amplitude-controllable output switching control signal.

[0052] The switching signal conversion module 300 includes a dual-gate N-channel MOSFET Q1, a DC voltage source VCC, and resistors R1, R2, R3, and R4. One end of resistor R1 is connected to the DC voltage source VCC, and the other end is connected to resistor R9 in the signal superposition module 400 and the drain (D) of the dual-gate N-channel MOSFET Q1. One end of resistor R2 is connected to the reference voltage in the signal control module 100, and the other end is connected to resistor R3 and the second gate (G2) of the dual-gate N-channel MOSFET Q1. One end of resistor R3 is connected to the FPGA unit in the signal control module 100, and the other end is connected to resistor R2 and the second gate (G2) of the dual-gate N-channel MOSFET Q1. The two ends of resistor R4 are respectively connected to the second low-speed digital-to-analog converter DAC2 in the signal control module 100 and the first gate (G1) of the dual-gate N-channel MOSFET Q1. The source (S) of the dual-gate N-channel MOSFET Q1 is connected to signal ground (GND).

[0053] In the switch signal conversion module 300, when the high-speed switch control signal generated by the FPGA unit is low level V 开关(闭) At that time, the output voltage of the switch signal conversion module 300 is V. 幅值开关 :

[0054] V 幅值开关 =VCC (2)

[0055] Where VCC is the voltage of the DC voltage source connected to the drain of the dual-gate N-channel MOS transistor;

[0056] When the high-speed switching control signal generated by the FPGA unit is high level V 开关(开) At that time, the output voltage of the switch signal conversion module 300 is V. 幅值开关 :

[0057] V 幅值开关 =VCC-k·(V 幅值 -V th )·R1 (3)

[0058] Where VCC is the voltage of the DC voltage source connected to the drain of the dual-gate N-channel MOSFET; k is a correction factor, V 幅值 V is the amplitude control signal output by the second low-speed digital-to-analog converter DAC2. th R1 is the threshold turn-on voltage of the dual-gate N-channel MOSFET, and R1 is the resistance value of resistor R1.

[0059] Specifically, such as Figure 2 As shown, in the dual-gate N-channel MOS transistor Q1, V gs1 V gs2 V th and I D A diagram illustrating the relationship; where V gs1 V is the first gate (G1) voltage of the dual-gate N-channel MOSFET Q1. gs2 V is the second gate (G2) voltage of the dual-gate N-channel MOSFET Q1. th I represents the threshold turn-on voltage of the dual-gate N-channel MOSFET Q1. D This represents the leakage current of Q1 in the dual-gate N-channel MOSFET.

[0060] Specifically, V 开关 V 参考 and V gs2 From Kirchhoff's laws and the superposition law, we can obtain the following related formulas:

[0061]

[0062] Among them, V 开关 For FPGA control of high-speed switching signal output level, V 参考 R2 and R3 are the reference voltage in the signal control module 100, and R2 and R3 are the resistance values ​​of resistors R2 and R3.

[0063] V gs1 and V 幅值The following related formulas are derived from Kirchhoff's laws:

[0064] V gs1 =V 幅值 (5)

[0065] Among them, V 幅值 This is the amplitude control signal output by the second low-speed digital-to-analog converter;

[0066] I D VCC and V 幅值开关 The following related formulas are derived from Kirchhoff's laws:

[0067] V 幅值开关 =VCC-I D ·R1 (6)

[0068] Figure 2 In this context, D represents a threshold voltage greater than the threshold turn-on voltage of a dual-gate N-channel MOSFET, but less than the maximum voltage that Q1 in a dual-gate N-channel MOSFET can withstand; for example... Figure 2 When the high-speed switch control signal is V 开关(闭) V gs2 <V th This indicates the laser is off when the high-speed switch control signal is V. 开关(开) When, it represents the laser being on, V gs2 Fixed, I D With V gs1 As I increases, I can be approximated. D See it as about V gs1 The direct proportional function is expressed as:

[0069] I D =k·(V gs1 -V th (7)

[0070] Due to V gs1 and V 幅值 They are equal, so we can get I. D and V 幅值 The expression is:

[0071] I D =k·(V 幅值 -V th (8)

[0072] Formulas (4), (5), (6), (7), and (8) are rearranged to form a formula concerning V. 幅值开关 V 幅值 V 开关 V th The formula for VCC, when the high-speed switching control signal generated by the FPGA unit is low level V...开关(闭) At that time, the output voltage of the switch signal conversion module 300 is V. 幅值开关 :

[0073] V 幅值开关 =VCC (2)

[0074] When the high-speed switching control signal generated by the FPGA unit is high level V 开关(开) At that time, the output voltage of the switch signal conversion module 300 is V. 幅值开关 :

[0075] V 幅值开关 =VCC-k·(V 幅值 -V th )·R1 (3).

[0076] The signal superposition module 400 is used to add the output switch control signal and the buffer bias current control signal and output the superimposed voltage signal.

[0077] Specifically, the signal superposition module 400 includes a second operational amplifier A2, resistors R7, R8, and R9, and a capacitor C3. One end of resistor R7 is connected to the output terminal of operational amplifier A1 in the voltage follower module 200, and the other end is connected to the non-inverting input terminal of operational amplifier A2. One end of resistor R9 is connected to the drain (D) of the dual-gate N-channel MOS transistor Q1 in the switch signal conversion module 300, and the other end is connected to the inverting input terminal of operational amplifier A2, resistor R8, and capacitor C3. The other end of resistor R8 is connected to the output terminal of operational amplifier A2, resistor R10, and the other end of capacitor C3. The other end of resistor R10 is connected to the non-inverting input terminal of operational amplifier A3 in the voltage-controlled current source module 500.

[0078] In the signal superposition module 400, the resistance values ​​of resistors R8 and R9 are equal. According to Kirchhoff's laws, the output voltage V of the second operational amplifier... 差分输出 for:

[0079] V 差分输出 =2·V 跟随输出 -V 幅值开关 (9)

[0080] Among them, V 幅值开关 V is the output voltage of the switch signal conversion module 300. 跟随输出 This is the output voltage of the voltage follower module 200.

[0081] The voltage-controlled current source module 500 is used to convert the superimposed voltage signal into a current signal in order to provide operating current for the multi-wavelength array laser module.

[0082] Specifically, the voltage-controlled current source module 500 includes a third operational amplifier A3, a fourth operational amplifier A4, an NPN transistor Q2, resistors R10, R11, R12, R13, R14, R15, R16, R17, R18 and R19, and a capacitor C4.

[0083] The other end of the resistor R11 is connected to the base of the NPN transistor Q2;

[0084] The two ends of the resistor R12 are respectively connected to the DC voltage source VCC and the collector of the NPN transistor Q2;

[0085] One end of resistor R13 is connected to the emitter of NPN transistor Q2, and the other end is connected to resistors R14 and R16;

[0086] The other end of resistor R14 is connected to resistor R15 and the multi-wavelength laser array module;

[0087] The other end of resistor R15 is connected to the inverting input of operational amplifier A4 and resistor R18;

[0088] The other end of resistor R16 is connected to the non-inverting input of operational amplifier A4 and resistor R17;

[0089] The other end of resistor R17 is connected to signal ground (GND);

[0090] The other end of resistor R18 is connected to the output of operational amplifier A4 and resistor R19;

[0091] The other end of the resistor R19 is connected to the capacitor C4 and the inverting input terminal of the operational amplifier A3;

[0092] The other end of capacitor C4 is connected to the output of operational amplifier A3.

[0093] In the voltage-controlled current source module 500, the resistance values ​​of resistors R15, R16, R17, and R18 are equal, and the operating current I of the multi-wavelength laser array module is... 工作电流 for:

[0094]

[0095] Among them, V 差分输出 R14 is the output voltage of the second operational amplifier, and R14 is the resistance value of resistor R14.

[0096] Specifically, substituting the above formulas (2), (3), and (9) into formula (10), when the high-speed switching control signal generated by the FPGA unit is low level V... 开关(闭) At that time, the operating current I of the multi-wavelength laser array module 工作电流 for:

[0097]

[0098] In this state, the laser is off, and I in this state 工作电流 This represents the bias current of the laser. Since different lasers have different bias currents, V can be adjusted for different lasers. 偏置电流 This provides a suitable bias current, allowing the wavelength of the working channel to be emitted smoothly, while reducing the impact of relaxation oscillations and improving the tuning speed.

[0099] When the high-speed switching control signal generated by the FPGA unit is high level V 开关(开) At that time, the operating current I of the multi-wavelength laser array module 工作电流 for:

[0100]

[0101] In this state, the laser is on, and I is in this state. 工作电流 This is expressed as the operating current of the laser, through V 幅值 It can stably regulate I 工作电流 .

[0102] This invention does not require a high-speed digital-to-analog converter as the laser driving current source. It can achieve high-speed switching between wavelengths by controlling only a low-speed digital-to-analog converter and an FPGA unit, ensuring the stability after wavelength switching, and the switching speed can reach the nanosecond level.

[0103] In another embodiment, a tunable laser is provided, using the driving circuit of the tunable laser described above.

[0104] For a more detailed explanation of the above-mentioned driving circuit, please refer to the relevant content disclosed in the foregoing embodiments, which will not be repeated here.

[0105] In another embodiment, a driving circuit for a tunable laser is provided, using one of the driving current sources as an example for analysis.

[0106] Set the reference voltage V for the signal control module to 100. 参考 The voltage is 2.5V, the resistance of R2 is 1KΩ, the resistance of R3 is 650Ω, and the high-speed switching signal V controlled by the FPGA is... 开关 When the signal is high, the output voltage is 3.3V, and the high-speed switching signal V controlled by the FPGA is... 开关 When the level is low, the output voltage is 0V, according to the following formula:

[0107]

[0108] In this embodiment, the dual-gate N-channel MOSFET Q1 in the switch signal conversion module 300 is a Toshiba 3SK195 dual-gate N-channel MOSFET. According to the datasheet of this chip, the threshold turn-on voltage V of the dual-gate N-channel MOSFET Q1 can be found. th Since the value is 1V, it can be concluded that when the high-speed switching control signal is V 开关(闭) At that time, V gs2 When the voltage is equal to 0.98V, the laser is in the off state. This occurs when the high-speed switch control signal is V. 开关(开) At that time, V gs2 The voltage is 2.98V, and the laser is in the on state.

[0109] When the high-speed switch control signal is V 开关(闭) Time I 工作电流 V 幅值 V 开关 V th V 偏置电流 The expression for VCC is:

[0110]

[0111] In this embodiment, V is set 偏置电流 With a voltage of 3.1V, a resistance of 10Ω for R14, and a VCC voltage of 6V, the transparent current of this channel can be calculated to be 20mA.

[0112] When the high-speed switch control signal is V 开关(开) Time I 工作电流 V 幅值 V 开关 V th V 偏置电流 The expression for VCC is:

[0113]

[0114] Because the switching signal conversion module 300 contains the following formula:

[0115] I D =k·(V 幅值 -V th )

[0116] Therefore I 工作电流 It can be represented as:

[0117]

[0118] In this embodiment, V is set 偏置电流 The voltage is 3.1V, the resistance of R14 is 10Ω, the resistance of R1 is 40Ω, the VCC voltage is 6V, and the leakage current I of the dual-gate N-channel MOSFET is... DIf the control range is 0-20mA, then the operating current range of this channel can be calculated to be 20mA-100mA.

[0119] The switching speed of the circuit in this embodiment is limited by the rise time and fall time of the dual-gate N-channel MOSFET, which are typically in the nanosecond range. An FPGA unit is used to control the switching frequency of the dual-gate N-channel MOSFET to meet the nanosecond-level switching requirements of different laser channels.

[0120] This embodiment provides a driving circuit for a multi-wavelength fast tunable laser with a bias current of 20mA, an operating current range of 20mA-100mA, and a switching time in the nanosecond range, which is in line with the application of multi-wavelength fast tunable lasers in optical switching systems.

[0121] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0122] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A driving circuit for a multi-wavelength laser array module, characterized by, It includes a signal control module, a voltage follower module, a switching signal conversion module, a signal superposition module, and a voltage-controlled current source module; The signal control module is connected to the input terminals of the voltage follower module and the switch signal conversion module, respectively; the signal superposition module is connected to the output terminals of the voltage follower module and the switch signal conversion module, respectively; the output terminal of the signal superposition module is connected to the input terminal of the voltage-controlled current source module. The signal control module is used to provide bias current control signal, amplitude control signal and high-speed switching control signal; the bias current control signal is generated by a first low-speed digital-to-analog converter, the amplitude control signal is generated by a second low-speed digital-to-analog converter, and the high-speed switching control signal is generated by an FPGA unit; The voltage follower module is used to buffer the bias current control signal and generate a buffered bias current control signal. The switching signal conversion module includes a dual-gate N-channel MOSFET, a VCC DC voltage source, resistors R1, R2, R3, and R4. The first gate of the dual-gate N-channel MOSFET is connected to a second low-speed digital-to-analog converter via resistor R4, and the second gate is connected to the output terminal of the FPGA unit via resistor R3 and to the reference voltage output terminal via resistor R2. The first drain of the dual-gate N-channel MOSFET is connected to a signal superposition module, and the second drain is connected to the VCC DC voltage source via resistor R1. The source of the dual-gate N-channel MOSFET is connected to signal ground. The high-speed switching control signal and the amplitude control signal work together to change the drain current of the dual-gate N-channel MOSFET, thereby converting the high-speed switching control signal and the amplitude control signal into an amplitude-controllable output switching control signal. The signal superposition module is used to add the output switch control signal and the buffer bias current control signal, and output the superimposed voltage signal. The voltage-controlled current source module is used to convert the superimposed voltage signal into a current signal in order to provide operating current for the multi-wavelength array laser module.

2. The drive circuit according to claim 1, characterized in that, Both the first low-speed digital-to-analog converter and the second low-speed digital-to-analog converter are controlled by the FPGA unit in the signal control module; the reference voltage used by the switching signal conversion module is output through the signal control module.

3. The drive circuit according to claim 1, characterized by The voltage follower module includes a first operational amplifier, resistors R5 and R6, and capacitors C1 and C2. The non-inverting input of the first operational amplifier is connected to a first low-speed digital-to-analog converter through resistor R5 and grounded through capacitor C1. The inverting input of the first operational amplifier is connected to the output through resistor R6 and is connected in parallel across resistor R6 through capacitor C2. The output of the first operational amplifier is connected to a signal superposition module.

4. The driving circuit according to claim 1, characterized in that, When the high-speed switching control signal generated by the FPGA unit is low, the output voltage of the switching signal conversion module is : in, The voltage of the DC voltage source VCC connected to the drain of the dual-gate N-channel MOSFET; When the high-speed switching control signal generated by the FPGA unit is high, the output voltage of the switching signal conversion module is : in, The voltage of the DC voltage source VCC connected to the drain of the dual-gate N-channel MOSFET; For correction factor, This is the amplitude control signal output by the second low-speed digital-to-analog converter. This refers to the threshold turn-on voltage of a dual-gate N-channel MOSFET. Let R1 be the resistance value.

5. The driving circuit according to claim 1, characterized in that, The signal superposition module includes a second operational amplifier, resistors R7, R8 and R9, and capacitor C3. The non-inverting input of the second operational amplifier is connected to the voltage follower module through R7, and the output is connected to the voltage-controlled current source module. The inverting input is connected to the output of the second operational amplifier through resistor R8 and to the switching signal conversion module through resistor R9. Capacitor C3 is connected in parallel across resistor R8.

6. The driving circuit according to claim 5, characterized in that, The resistance R8 and the resistance R9 have the same resistance value, and the output voltage V 差分输出 is: in, The output voltage of the switch signal conversion module. This is the output voltage of the voltage follower module.

7. The driving circuit according to claim 1, characterized in that, The voltage-controlled current source module includes a third operational amplifier, a fourth operational amplifier, an NPN transistor, resistors R10, R11, R12, R13, R14, R15, R16, R17, R18 and R19, and a capacitor C4. The non-inverting input of the third operational amplifier is connected to the output of the signal superposition module through resistor R10, and the output of the third operational amplifier is connected to the base of the NPN transistor through resistor R11; the first path of the inverting input of the third operational amplifier is connected to the output of the third operational amplifier through capacitor C4, and the second path of the inverting input is connected to resistor R19. The collector of the NPN transistor is connected to a DC voltage source through resistor R12; the emitter of the NPN transistor is connected to a multi-wavelength laser array module through resistors R13 and R14. One end of resistor R14 is connected to the non-inverting input of the fourth operational amplifier through resistor R16. The non-inverting input of the fourth operational amplifier is grounded through resistor R17. The output of the third operational amplifier is connected to resistor R19 and connected to the other end of resistor R14 through resistors R18 and R15. The inverting input of the fourth operational amplifier is connected to resistor R15.

8. The driving circuit according to claim 7, characterized in that, The resistance values ​​of resistors R15, R16, R17, and R18 are equal, and the operating current of the multi-wavelength laser array module is... : Among them, V 差分输出 This is the output voltage of the second operational amplifier. This is the resistance value of resistor R14.

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