CN203747238U - A pulsed semiconductor laser drive circuit - Google Patents

Abstract

The utility model relates to a pulse type semiconductor laser driving circuit. The pulse type semiconductor laser driving circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a capacitor C1, a capacitor C2, a diode D1, a diode D2, a variable voltage transformer T1, a crystal triode N1, a crystal triode N2 and a semiconductor laser LD1, wherein the resistor R3, the resistor R5, the crystal triode N2, the diode D1, the resistor R4 and the variable voltage transformer T1 form a triggering circuit, and the resistor R1, the resistor R2, the resistor R6, the resistor R7, the crystal triode N1, the diode D2, the capacitor C2, the capacitor C1 and the semiconductor laser LD1 jointly form a semiconductor laser pulse driving circuit. With the pulse type semiconductor laser driving circuit of the utility model adopted, a plurality of nanosecond-grade narrow-pulse width high-peak power laser pulses can be realized, and the problems of small driving current and low driving speed of traditional bipolar, metal oxide field-effect transistor driving circuits can be solved.

Description

A pulsed semiconductor laser drive circuit

technical field

The utility model relates to a pulsed semiconductor laser drive circuit.

Background technique

The pulsed semiconductor laser drive circuit can drive the semiconductor laser to generate pulsed laser, which can be used in distributed Raman fiber temperature sensors, pulsed laser range finders and other fields. In the distributed Raman fiber optic temperature sensor, the smaller the pulse width of the pump laser pulse, the higher the temperature spatial resolution that the system can achieve. For the pulsed laser range finder, the smaller the pulse width of the emitted laser, the higher the distance measurement accuracy can be achieved. The narrowing of the laser pulse width means the reduction of the laser pulse energy. In order not to affect the range measurement of the system and maintain the necessary pulse energy, it is necessary to increase the peak power of the laser pulse. Therefore, the laser pulse light source with high peak power and narrow pulse width is of great significance to improve the performance indicators of distributed Raman fiber optic temperature sensors and pulsed laser range finders.

The peak power of pulsed semiconductor lasers (such as 905nm and 980nm series) on the market can reach tens of watts, and the corresponding peak driving current can reach tens of amperes. The general driving circuit based on bipolar triode and metal oxide field effect transistor is difficult to realize the narrow pulse width laser pulse with a half pulse width of several ns level under such a large driving current due to the large junction capacitance and other reasons. The narrow half pulse width generally exceeds 20ns. Although the pulsed fiber laser can generally amplify the seed light with low peak power and narrow pulse width through an optical amplifier to achieve a few ns-level narrow pulse width and high peak power laser pulse, it is expensive and bulky.

Contents of the invention

The purpose of this utility model is to provide a pulsed semiconductor laser drive circuit with simple structure and low cost.

The pulsed semiconductor laser drive circuit of the utility model includes: resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, resistor R6, resistor R7, capacitor C1, capacitor C2, diode D1, diode D2, voltage transformer T1 , transistor N1, transistor N2 and semiconductor laser LD1, one end of the resistor R3 is connected to one end of the resistor R5 and the base of the transistor N2, the other end of the resistor R5 and the emitter of the transistor N2 are connected to the signal ground, and the transistor The collector of N2 is connected to the anode of diode D1 and one end of resistor R4, the other end of resistor R4 is connected to one end of the primary coil of transformer transformer T1, and the other end of the primary coil of transformer transformer T1 is connected to the negative pole of diode D1 5V-12V DC stabilized power supply, diode D2, resistor R6, capacitor C2 and semiconductor laser LD1 form a parallel circuit, wherein the positive pole of semiconductor laser LD1 is connected to the negative pole of diode D2, and the negative pole of semiconductor laser LD1 is connected to the positive pole of diode D2. The connection terminal of the positive pole of the semiconductor laser LD1 and the negative pole of the diode D2 in the parallel circuit is connected with the emitter pole of the transistor N1 and one end of the secondary coil of the transformer transformer T1, and the connection terminal of the negative pole of the semiconductor laser LD1 and the positive pole of the diode D2 in the parallel circuit Connected to the power ground, the other end of the secondary coil of the transformer transformer T1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the base of the transistor N1, the collector of the transistor N1 and one end of the resistor R1 and the capacitor One end of C1 is connected, the other end of resistor R1 is connected with an adjustable DC power supply of 200V-300V, the other end of capacitor C1 is connected with one end of resistor R7, and the other end of resistor R7 is connected with power ground.

The beneficial effects of the utility model are:

The pulsed semiconductor laser drive circuit of the utility model adopts a fast high-current pulse drive circuit based on an avalanche triode, combined with a transformer transformer trigger circuit and auxiliary capacitors connected in parallel at both ends of the semiconductor laser to further narrow the pulse width and increase the peak power. The laser pulse with narrow pulse width and high peak power at the level of several ns is realized, which solves the problems of small driving current and slow driving speed of traditional bipolar and metal oxide field effect transistor driving circuits. Compared with fiber lasers, the drive circuit has lower cost, lower power consumption, and smaller size, and can be applied to distributed Raman fiber optic temperature sensors, pulsed laser rangefinders and other fields.

Description of drawings

Figure 1 is a circuit schematic diagram of a pulsed semiconductor laser drive circuit.

Detailed ways

Further illustrate the utility model below in conjunction with accompanying drawing.

Referring to Fig. 1, the pulsed semiconductor laser drive circuit of the present invention includes: resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, resistor R6, resistor R7, capacitor C1, capacitor C2, diode D1, diode D2, variable Pressure transformer T1, transistor N1, transistor N2 and semiconductor laser LD1, one end of resistor R3 is connected to one end of resistor R5 and the base of transistor N2, the other end of resistor R5 and the emitter of transistor N2 are connected to the signal ground connected, the collector of transistor N2 is connected with the anode of diode D1 and one end of resistor R4, the other end of resistor R4 is connected with one end of primary coil of transformer transformer T1, and the other end of primary coil of transformer transformer T1 is connected with diode D1 The negative poles of the diodes are connected to the 5V-12V DC stabilized power supply VCC, and the diode D2, the resistor R6, the capacitor C2 and the semiconductor laser LD1 form a parallel circuit, wherein the positive pole of the semiconductor laser LD1 is connected to the negative pole of the diode D2, and the negative pole of the semiconductor laser LD1 is connected to the diode The positive pole of D2 is connected, the connection end of the positive pole of the semiconductor laser LD1 and the negative pole of the diode D2 in the parallel circuit is connected with the emitter of the transistor N1 and one end of the secondary coil of the transformer transformer T1, the negative pole of the semiconductor laser LD1 and the diode in the parallel circuit The connection end of the positive pole of D2 is connected to the power ground, the other end of the secondary coil of the transformer transformer T1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the base of the transistor N1, the collector of the transistor N1 and the resistor One end of R1 is connected to one end of capacitor C1, the other end of resistor R1 is connected to 200V-300V adjustable DC power supply HV, the other end of capacitor C1 is connected to one end of resistor R7, and the other end of resistor R7 is connected to power ground.

In the figure, INPUT represents the trigger signal input terminal. Resistor R3, resistor R5, crystal triode N2, diode D1, resistor R4, transformer transformer T1 form a trigger circuit. Resistor R3 and resistor R5 form the input drive network of the trigger circuit, transformer transformer T1, resistor R4, and transistor N2 form the transformer transformer driving circuit, and diode D1 is used to protect transformer transformer T1. Resistor R1, resistor R2, resistor R6, resistor R7, transistor N1, diode D2, capacitor C2, capacitor C1 and semiconductor laser LD1 together form a semiconductor laser pulse drive circuit. Among them, the 200V-300V adjustable DC power supply HV, resistor R1, capacitor C1, resistor R7, and power ground form a charging circuit for capacitor C1, and capacitor C1, resistor R7, semiconductor laser LD1, and transistor N1 form the discharge of capacitor C1. In the circuit, the diode N2 and the resistor R6 are used to protect the semiconductor laser LD1 from being damaged by the reverse voltage pulse, and the capacitor C2 is used as an auxiliary energy storage capacitor to further compress the half pulse width of the laser pulse and increase the peak power of the laser pulse.

Transistor N1 adopts fast high-voltage and high-current avalanche triode, such as ZTX415 avalanche transistor produced by Zetex Company, its collector-base reverse breakdown voltage VCBO can reach 260V, and the maximum collector pulse (when the half pulse width is 20ns) Current ICM up to 60A. Diode D2 uses a fast Schottky diode, such as MUR160. Transformer transformer T1 adopts fast transformer transformer, such as ADT1-1WT. Transistor N1 adopts fast switching transistor, such as FBR520. In order to reduce the influence of distributed inductance of the device, multiple capacitors can be connected in parallel for the capacitor C1, and multiple resistors can be connected in parallel for the resistor. The devices used should be small-sized surface mount packages as much as possible, and the pins of the semiconductor laser LD1 should be as short as possible. When making printed circuit boards, in order to reduce the influence of circuit board distribution parameters as little as possible, the printed circuit board should be designed according to the principle of fast circuit design, such as: the layout of components should be as compact as possible, the leads between devices should be as short as possible, and the Large areas of ground, etc.

When working, it is necessary to input a trigger pulse signal at the input end of the narrow pulse width and high peak power pulsed semiconductor laser drive circuit. The half pulse width of the trigger pulse is about 50 ns. When the trigger pulse signal is at a low level, the transistor N2 is cut off. The primary coil of the transformer transformer T1 has no current passing through it, and the secondary coil has no voltage signal output. At this time, the transistor N1 is in the cut-off state, and the 200V-300V adjustable DC power supply HV passes through the circuit composed of the capacitor C1, the resistor R7 and the power ground. Charge capacitor C1. When the trigger pulse signal is at a high level, the transistor N2 is turned on, the primary coil of the transformer transformer T1 has a current passing through it, and the secondary coil outputs an amplified voltage signal to drive the transistor N1. At this time, the transistor N1 enters an avalanche state. The capacitor C1 is discharged through the CE junction of the transistor N1, the semiconductor laser LD1, and the resistor R7. At this time, the semiconductor laser LD1 has a pulse current with a fast and large peak current, so that the semiconductor laser LD1 is driven to emit a laser pulse with a narrow pulse and high peak power. C2 absorbs part of the energy during the discharge of capacitor C1, and releases energy when the current in semiconductor laser LD1 is at its peak state, thereby further narrowing the pulse width of the laser pulse and increasing the peak optical power. The use of transformer transformer T1 can increase the driving voltage between the base and emitter of transistor N1, and speed up the time for transistor N1 to enter the avalanche state. In addition, its unique transformer transformer drive circuit can also isolate the trigger circuit and effectively suppress Interference of the bounce signal to the shape of the laser pulse.

The value of capacitor C1 can be estimated according to the following formula (1):

C1×Uc=Ip×τ (1)

Among them, C1 is the capacitance value of the capacitor C1, Uc is the maximum voltage value when the capacitor C1 is charged, Ip is the peak current when the capacitor C1 is discharged, and τ is the half pulse width of the laser pulse. Assuming that Ip is 50A, Uc is 250V, and τ is 5ns, the value of capacitor C1 is about 1nF.

The value of the capacitor C2 is roughly distributed between 100pF and 400pF due to the different distribution parameters of the specific printed circuit, and the specific value can be selected according to the experimental situation. The resistance R1 can be determined according to the repetition frequency of the pulse, generally tens of KΩ. Resistor R7 is a current-limiting resistor, generally several Ω, which can be adjusted according to the actual required laser drive current.

Claims (1)

1. a pulse type semiconductor laser drive circuit, it is characterized in that comprising: resistance R 1, resistance R 2, resistance R 3, resistance R 4, resistance R 5, resistance R 6, resistance R 7, capacitor C 1, capacitor C 2, diode D1, diode D2, transformation instrument transformer T1, transistor N1, transistor N2 and semiconductor laser LD1, one end of one end of resistance R 3 and resistance R 5 and the base stage of transistor N2 are connected, the emitter of the other end of resistance R 5 and transistor N2 is connected with signal ground, the collector electrode of transistor N2 is connected with the positive pole of diode D1 and one end of resistance R 4, the other end of resistance R 4 is connected with one end of transformation instrument transformer T1 primary winding, the other end of transformation instrument transformer T1 primary winding is connected 5V-12V D.C. regulated power supply (VCC) jointly with the negative pole of diode D1, diode D2, resistance R 6, capacitor C 2 and semiconductor laser LD1 composition parallel circuits, wherein, the positive pole of semiconductor laser LD1 is connected with the negative pole of diode D2, the negative pole of semiconductor laser LD1 is connected with the positive pole of diode D2, semiconductor laser LD1 positive pole in parallel circuits is connected with one end of the link of diode D2 negative pole and the emitter of transistor N1 and transformation instrument transformer T1 secondary coil, semiconductor laser LD1 negative pole in parallel circuits is connected with Power Groud with the link of diode D2 positive pole, the other end of transformation instrument transformer T1 secondary coil is connected with one end of resistance R 2, the other end of resistance R 2 is connected with the base stage of transistor N1, one end of the collector electrode of transistor N1 and resistance R 1 and one end of capacitor C 1 are connected, the other end of resistance R 1 is connected with the adjustable DC power supply (HV) of 200V-300V, the other end of capacitor C 1 is connected with one end of resistance R 7, the other end of resistance R 7 is connected with Power Groud.