Automatic optical power control circuit and control method for laser

Abstract

The invention relates to the technical field of analog optical communication, in particular to an automatic optical power control circuit and method for a laser, and the circuit comprises an operational amplification following sub-circuit, an operational amplification subtraction sub-circuit, an operational amplification integral sub-circuit, and a triode sub-circuit. Positive voltages of the operational amplification following sub-circuit, the operational amplification subtraction sub-circuit and the operational amplification integral sub-circuit are all connected with + 5V, and negative voltages are all connected with-5V. Through the arrangement of the operational amplification following sub-circuit, the operational amplification subtraction sub-circuit, the operational amplification integral sub-circuit and the triode sub-circuit, the stability of the output power of the laser can be effectively ensured, the output power of the laser can be controlled, and meanwhile, chips adopted by the laser are operational amplifiers and triodes, so that the integration is easy, and the size is small; the circuit is simple, the circuit structure is simple, the cost is low, the method is simple and practical, and therefore the problem that an existing laser automatic optical power control circuit is high in production cost is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of analog optical communication, and in particular to a laser automatic optical power control circuit and a control method. Background Art

[0002] As a key device in the field of analog optical communications, the laser output optical power can directly affect various indicators of the analog optical link, such as 1dB compression point, phase stability, link gain and other indicators. Especially for external modulation links, the link gain is proportional to the square of the optical power, and the stability of the optical power directly affects the stability of the link gain.

[0003] The present invention provides a laser automatic optical power control circuit and control method, which can adjust the optical power by simply rotating a potentiometer to change the resistance value of the potentiometer, and the circuit can keep the optical power stable under high and low temperature conditions. Summary of the invention

[0004] The purpose of the present invention is to provide a laser automatic optical power control circuit and a control method, aiming to solve the problem of high production cost of the existing laser automatic optical power control circuit.

[0005] To achieve the above-mentioned purpose, in the first aspect, the present invention provides a laser automatic optical power control circuit, comprising an operational amplifier follower subcircuit, an operational amplifier subtraction subcircuit, an operational amplifier integrator subcircuit and a triode subcircuit; the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit, the operational amplifier integrator subcircuit and the triode subcircuit are connected in sequence, and the positive voltages of the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit and the operational amplifier integrator subcircuit are all connected to +5V, and the negative voltages are all connected to -5V.

[0006] Wherein, the operational amplifier follower subcircuit includes an operational amplifier follower U3A, a filter capacitor C14, a filter capacitor C19, a filter capacitor C22, a filter capacitor C24, a resistor R12, a resistor R11, a filter capacitor C21 and a filter capacitor C23; the positive voltage end of the operational amplifier follower U3A is connected to the filter capacitor C14 and the filter capacitor C19; the negative voltage end of the operational amplifier follower U3A is connected to the filter capacitor C22 and the filter capacitor C24; the positive input end of the operational amplifier follower U3A is connected to the resistor R12, the other end of the resistor R12 is connected to the resistor R11, and is connected to the laser backlight detector power supply end LD_MPD, the laser backlight detector power supply end LD_MPD is connected in series with the filter capacitor C21 and the filter capacitor C23, and the other end of the resistor R11 is connected to a -5V power supply; the negative input end of the operational amplifier follower U3A is connected to the output end of the operational amplifier follower U3A.

[0007] Wherein, the operational amplifier subtraction subcircuit includes an operational amplifier subtractor U1A, a filter capacitor C3, a filter capacitor C6, a filter capacitor C10, a filter capacitor C17, a resistor R8, a resistor R6, a resistor R3, a resistor R1 and a potentiometer R2; the positive voltage end of the operational amplifier subtractor U1A is connected to the filter capacitor C3 and the filter capacitor C6, and the negative voltage end of the operational amplifier subtractor U1A is connected to the filter capacitor C10 and the filter capacitor C17; the positive input end of the operational amplifier subtractor U1A is connected to the resistor R8 to the ground, and the resistor R6 to the output end of the operational amplifier follower U3A; the negative input end of the operational amplifier subtractor U1A is connected to the resistor R3, and the resistor R1 is connected to the output end of U1A, the other end of the resistor R3 is connected to the potentiometer R2, and one end of the potentiometer R2 is grounded and connected to -5V.

[0008] Among them, the operational amplifier integrator circuit includes an operational amplifier integrator U2A, a filter capacitor C7, a filter capacitor C8, a filter capacitor C15, a filter capacitor C20, a resistor R4, a capacitor C4, a capacitor C5, a capacitor C1 and a capacitor C2; the positive voltage end of the operational amplifier integrator U2A is connected to the filter capacitor C7 and the filter capacitor C8, the negative voltage end of the operational amplifier integrator U2A is connected to the filter capacitor C15 and the filter capacitor C20, and the positive input end of the operational amplifier integrator U2A is grounded; the negative input end of the operational amplifier integrator U2A is connected to the resistor R4 to the output end of the operational amplifier subtractor U1A, and to the output end of the operational amplifier integrator U2A with the capacitor C4 and the capacitor C5, the capacitor C4 and the capacitor C5 are connected in parallel with the capacitor C1 and the C2, and the capacitor C1 and the C2 are connected in series.

[0009] Among them, the operational amplifier integrator circuit includes an operational amplifier integrator U2A, a filter capacitor C7, a filter capacitor C8, a filter capacitor C15, a filter capacitor C20, a resistor R4, a capacitor C4, a capacitor C5, a capacitor C1 and a capacitor C2; the positive voltage end of the operational amplifier integrator U2A is connected to the filter capacitor C7 and the filter capacitor C8, the negative voltage end of the operational amplifier integrator U2A is connected to the filter capacitor C15 and the filter capacitor C20, and the positive input end of the operational amplifier integrator U2A is grounded; the negative input end of the operational amplifier integrator U2A is connected to the resistor R4 to the output end of the operational amplifier subtractor U1A, and to the output end of the operational amplifier integrator U2A with the capacitor C4 and the capacitor C5, the capacitor C4 and the capacitor C5 are connected in parallel with the capacitor C1 and the C2, and the capacitor C1 and the C2 are connected in series.

[0010] In a second aspect, a laser automatic optical power control circuit control method is provided, which is used in the laser automatic optical power control circuit described in the first aspect, and comprises the following steps:

[0011] Determine the resistance value of resistor R11 according to the maximum output optical power of the laser and the responsiveness of the laser backlight detector;

[0012] Determine the resistance values ​​of the current limiting resistors R7, R9 and R10 according to the maximum output optical power of the laser, the bias voltage when the laser has the maximum output optical power and the minimum collector-emitter voltage when the transistor operates in the amplification region;

[0013] Based on the resistance value, the voltage value of the potentiometer R2 is changed to adjust the output optical power of the laser to the target value.

[0014] The invention discloses an automatic optical power control circuit for a laser, comprising an operational amplifier follower subcircuit, an operational amplifier subtraction subcircuit, an operational amplifier integration subcircuit and a triode subcircuit; the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit, the operational amplifier integration subcircuit and the triode subcircuit are connected in sequence, and the positive voltages of the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit and the operational amplifier integration subcircuit are all connected to +5V, and the negative voltages are all connected to -5V. The invention can effectively ensure the stability of the output power of the laser and realize the control of the output power of the laser by setting the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit, the operational amplifier integration subcircuit and the triode subcircuit. At the same time, the chips used in the invention are operational amplifiers and triodes, which are easy to integrate and small in size; the circuit is simple, the circuit architecture is simple, the cost is low, and the method is simple and practical, thereby solving the problem of high production cost of the existing automatic optical power control circuit for lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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.

[0016] Figure 1 The invention discloses a circuit diagram of a laser automatic optical power control circuit.

[0017] Figure 2 The present invention provides a flow chart of a laser automatic optical power control circuit control method. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0019] See also Figure 1 In the first aspect, the present invention provides a laser automatic optical power control circuit, comprising an operational amplifier follower subcircuit, an operational amplifier subtraction subcircuit, an operational amplifier integrator subcircuit and a triode subcircuit; the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit, the operational amplifier integrator subcircuit and the triode subcircuit are connected in sequence, and the positive voltages of the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit and the operational amplifier integrator subcircuit are all connected to +5V, and the negative voltages are all connected to -5V.

[0020] Furthermore, the operational amplifier follower subcircuit includes an operational amplifier follower U3A, a filter capacitor C14, a filter capacitor C19, a filter capacitor C22, a filter capacitor C24, a resistor R12, a resistor R11, a filter capacitor C21 and a filter capacitor C23; the positive voltage end of the operational amplifier follower U3A is connected to the filter capacitor C14 and the filter capacitor C19; the negative voltage end of the operational amplifier follower U3A is connected to the filter capacitor C22 and the filter capacitor C24; the positive input end of the operational amplifier follower U3A is connected to the resistor R12, the other end of the resistor R12 is connected to the resistor R11, and is connected to the laser backlight detector power supply end LD_MPD, the laser backlight detector power supply end LD_MPD is connected in series with the filter capacitor C21 and the filter capacitor C23, and the other end of the resistor R11 is connected to a -5V power supply; the negative input end of the operational amplifier follower U3A is connected to the output end of the operational amplifier follower U3A.

[0021] Furthermore, the operational amplifier subtraction subcircuit includes an operational amplifier subtractor U1A, a filter capacitor C3, a filter capacitor C6, a filter capacitor C10, a filter capacitor C17, a resistor R8, a resistor R6, a resistor R3, a resistor R1 and a potentiometer R2; the positive voltage end of the operational amplifier subtractor U1A is connected to the filter capacitor C3 and the filter capacitor C6, and the negative voltage end of the operational amplifier subtractor U1A is connected to the filter capacitor C10 and the filter capacitor C17; the positive input end of the operational amplifier subtractor U1A is connected to the resistor R8 to the ground, and the resistor R6 to the output end of the operational amplifier follower U3A; the negative input end of the operational amplifier subtractor U1A is connected to the resistor R3, and the resistor R1 is connected to the output end of U1A, the other end of the resistor R3 is connected to the potentiometer R2, and one end of the potentiometer R2 is grounded and connected to -5V.

[0022] Furthermore, the operational amplifier integrator circuit includes an operational amplifier integrator U2A, a filter capacitor C7, a filter capacitor C8, a filter capacitor C15, a filter capacitor C20, a resistor R4, a capacitor C4, a capacitor C5, a capacitor C1 and a capacitor C2; the positive voltage end of the operational amplifier integrator U2A is connected to the filter capacitor C7 and the filter capacitor C8, the negative voltage end of the operational amplifier integrator U2A is connected to the filter capacitor C15 and the filter capacitor C20, and the positive input end of the operational amplifier integrator U2A is grounded; the negative input end of the operational amplifier integrator U2A is connected to the resistor R4 to the output end of the operational amplifier subtractor U1A, and to the output end of the operational amplifier integrator U2A with the capacitor C4 and the capacitor C5, the capacitor C4 and the capacitor C5 are connected in parallel with the capacitor C1 and the C2, and the capacitor C1 and the C2 are connected in series.

[0023] Furthermore, the transistor subcircuit includes an NPN transistor Q1, a resistor R5, a current limiting resistor R7, a filter capacitor C9, a filter capacitor C16, a current limiting resistor R9, a current limiting resistor R10, a reverse light emitting diode D1, a forward diode D2, a filter capacitor C11, a filter capacitor C12, a filter capacitor C13, a filter capacitor C18 and a magnetic bead L1; the base of the NPN transistor Q1 is connected to the resistor R5 to the output end of the operational amplifier integrator U2A; the emitter of the NPN transistor Q1 is connected to the current limiting Resistor R7 to -5V, the -5V is connected in series to the filter capacitor C9 and the filter capacitor C16; the collector of the NPN transistor Q1 is connected in series to the current limiting resistor R9 and the current limiting resistor R10, the current limiting resistor R10 is connected to the reverse light emitting diode D1, the forward diode D2, the filter capacitor C11, the filter capacitor C12, the filter capacitor C13 and the filter capacitor C18, and is connected to the magnetic bead L1, and the magnetic bead L1 is connected to the laser bias voltage supply terminal LD_BIA.

[0024] In this embodiment, the positive voltage terminal of the operational amplifier follower U3A is connected to two 0.1μF filter capacitors C14 and C19 connected in series to the ground, and the negative voltage terminal is connected to two 0.1μF filter capacitors C22 and C24 connected in series to the ground. The positive input terminal of U3A is connected to a 10kΩ resistor R12, and the other end of R12 is connected to a resistor R11 and the laser backlight detector power supply terminal LD_MPD. The LD_MPD terminal is connected to two filter capacitors C21 and C23 connected in series to the ground, and the R11 resistor is connected to a -5V power supply; the negative input terminal of U3A is connected to the output terminal of U3A. The positive voltage terminal of the operational amplifier subtractor U1A is connected to two 0.1μF filter capacitors C3 and C6 connected in series to the ground, and the negative voltage terminal is connected to two 0.1μF filter capacitors C10 and C17 connected in series to the ground. The positive input terminal of U1A is connected to a 100kΩ resistor R8 to the ground, and a 100kΩ resistor R6 is connected to the output terminal of U3A; the negative input terminal of U1A is connected to a 100kΩ resistor R3, and a 100kΩ resistor R1 is connected to the output terminal of U1A. The other end of R3 is connected to a 10kΩ potentiometer, one end of the potentiometer is grounded and the other end is connected to -5V. The positive voltage terminal of the operational amplifier integrator U2A is connected to two 0.1μF series-connected filter capacitors C7 and C8, and the negative voltage terminal is connected to two 0.1μF series-connected filter capacitors C15 and C20. The positive input terminal of U2A is grounded; the negative input terminal of U2A is connected to a 499kΩ resistor R4 to the output terminal of U1A, and two 1μF series capacitors C4 and C5 are connected to the output terminal of U2A. C4 and C5 are simultaneously connected in parallel with two 1μF series capacitors C1 and C2. The base of the NPN transistor Q1 is connected to a 1kΩ resistor to the output end of U2A; the emitter is connected to a current limiting resistor R7 to +5V, and +5V is simultaneously connected to two 0.1μF series filter capacitors C9 and C16 to the ground; the collector is connected to two series current limiting resistors R9 and R10, and the right side of R10 is connected to four reverse light-emitting diodes D1 to the ground, one forward diode D2 to the ground, a 100μF filter capacitor C11 to the ground, a 10μF filter capacitor C12 to the ground, and two 0.1μF series filter capacitors C13 and C18 to the ground, and finally a 60Ω magnetic bead L1 is connected, and the right side of L1 is connected to the laser bias voltage supply terminal LD_BIA.

[0025] The present invention can effectively ensure the stability of the laser output power and realize the control of the laser output power by setting the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit, the operational amplifier integration subcircuit and the triode subcircuit. At the same time, the chips adopted by the present invention are operational amplifiers and triodes, which are easy to integrate and small in size; the circuit is simple, the circuit architecture is simple, the cost is low, and the method is simple and practical, thereby solving the problem of high production cost of the existing laser automatic optical power control circuit.

[0026] See also Figure 2In a second aspect, a laser automatic optical power control circuit control method is provided for the laser automatic optical power control circuit described in the first aspect, comprising the following steps:

[0027] S1 determines the resistance value of resistor R11 according to the maximum output optical power of the laser and the responsiveness of the laser backlight detector;

[0028] Specifically, according to the maximum output optical power p of the laser max (in mW) and the laser backlight detector responsivity r pd (Unit: mA / mW) Determine the resistance value of R11. The resistance value of R11 is calculated as follows:

[0029]

[0030] S2 determines the resistance values ​​of the current limiting resistors R7, R9 and R10 according to the maximum output optical power of the laser, the bias voltage when the laser has the maximum output optical power and the minimum collector-emitter voltage of the transistor when it is operating in the amplification region;

[0031] Specifically, it is necessary to calculate the maximum output optical power p of the laser. max , bias voltage V when the laser outputs maximum optical power bias (take the absolute value), the laser slope efficiency l (unit: mW / mA) and the minimum collector-emitter voltage V when the transistor is operating in the amplification region min Determine the resistance of current limiting resistors R7, R9 and R10. The resistance calculation formula is as follows:

[0032]

[0033] S3 adjusts the laser output optical power to a target value by changing the voltage value of the potentiometer R2 based on the resistance value.

[0034] Specifically, after determining the resistance value of the above resistor in the circuit, the output optical power of the laser can be adjusted. If the target value of the laser output optical power is p (p < p max ), under this optical power condition, the backlight response of the laser is r pd2 , this can be achieved by simply adjusting the output voltage value of potentiometer R2 to the following value Vt.

[0035] Vt=p*r pd2 *R11-5

[0036] After the output voltage value of R2 is adjusted to Vt, if there is a slight error between the output optical power of the laser and the set value, the output optical power can be fine-tuned by rotating the potentiometer. The specific method is: if you want to increase the output optical power of the laser, you can rotate the R2 potentiometer to reduce the resistance of the potentiometer, thereby increasing the output voltage of the potentiometer. After the output voltage of the potentiometer increases, the output voltage of the operational amplifier subtractor U1A is negative, and the output voltage of the operational amplifier integrator U2A gradually increases. The current flowing through R5 increases, the collector current of Q1 increases, the current flowing through the laser increases, and the laser output power increases until the laser backlight detector L The D_MPD voltage value is consistent with the output voltage of the R2 potentiometer, and the circuit returns to a balanced state; if you want to reduce the output optical power of the laser, you can rotate the R2 potentiometer to increase the resistance of the potentiometer, thereby reducing the output voltage of the potentiometer. After the output voltage of the potentiometer decreases, the output voltage of the operational amplifier subtractor U1A is positive, and the output voltage of the operational amplifier integrator U2A gradually decreases, the current flowing through R5 decreases, the collector current of Q1 decreases, the current flowing through the laser decreases, and the laser output power decreases until the voltage value of the laser backlight detector LD_MPD is consistent with the output voltage of the R2 potentiometer, and the circuit returns to a balanced state.

[0037] What is disclosed above is only a preferred embodiment of a laser automatic optical power control circuit and control method of the present invention. Of course, this cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A laser automatic optical power control circuit, characterized in that: It includes an operational amplifier follower subcircuit, an operational amplifier subtraction subcircuit, an operational amplifier integrator subcircuit and a triode subcircuit; the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit, the operational amplifier integrator subcircuit and the triode subcircuit are connected in sequence, and the positive voltages of the operational amplifier follower subcircuit, the operational amplifier subtraction subcircuit and the operational amplifier integrator subcircuit are all connected to +5V, and the negative voltages are all connected to -5V.

2. The laser automatic optical power control circuit as claimed in claim 1, characterized in that: The operational amplifier follower subcircuit includes an operational amplifier follower U3A, a filter capacitor C14, a filter capacitor C19, a filter capacitor C22, a filter capacitor C24, a resistor R12, a resistor R11, a filter capacitor C21 and a filter capacitor C23; the positive voltage end of the operational amplifier follower U3A is connected to the filter capacitor C14 and the filter capacitor C19; the negative voltage end of the operational amplifier follower U3A is connected to the filter capacitor C22 and the filter capacitor C24; the positive input end of the operational amplifier follower U3A is connected to the resistor R12, the other end of the resistor R12 is connected to the resistor R11, and is connected to the laser backlight detector power supply end LD_MPD, the laser backlight detector power supply end LD_MPD is connected in series with the filter capacitor C21 and the filter capacitor C23, and the other end of the resistor R11 is connected to a -5V power supply; the negative input end of the operational amplifier follower U3A is connected to the output end of the operational amplifier follower U3A.

3. The laser automatic optical power control circuit as claimed in claim 2, characterized in that: The operational amplifier subtraction subcircuit includes an operational amplifier subtractor U1A, a filter capacitor C3, a filter capacitor C6, a filter capacitor C10, a filter capacitor C17, a resistor R8, a resistor R6, a resistor R3, a resistor R1 and a potentiometer R2; the positive voltage end of the operational amplifier subtractor U1A is connected to the filter capacitor C3 and the filter capacitor C6, and the negative voltage end of the operational amplifier subtractor U1A is connected to the filter capacitor C10 and the filter capacitor C17; the positive input end of the operational amplifier subtractor U1A is connected to the resistor R8 to the ground, and the resistor R6 to the output end of the operational amplifier follower U3A; the negative input end of the operational amplifier subtractor U1A is connected to the resistor R3, and the resistor R1 is connected to the output end of U1A, the other end of the resistor R3 is connected to the potentiometer R2, and one end of the potentiometer R2 is grounded and connected to -5V.

4. The laser automatic optical power control circuit as claimed in claim 3, characterized in that: The operational amplifier integrator circuit includes an operational amplifier integrator U2A, a filter capacitor C7, a filter capacitor C8, a filter capacitor C15, a filter capacitor C20, a resistor R4, a capacitor C4, a capacitor C5, a capacitor C1 and a capacitor C2; the positive voltage end of the operational amplifier integrator U2A is connected to the filter capacitor C7 and the filter capacitor C8, the negative voltage end of the operational amplifier integrator U2A is connected to the filter capacitor C15 and the filter capacitor C20, and the positive input end of the operational amplifier integrator U2A is grounded; the negative input end of the operational amplifier integrator U2A is connected to the resistor R4 to the output end of the operational amplifier subtractor U1A, and to the output end of the operational amplifier integrator U2A with the capacitor C4 and the capacitor C5, the capacitor C4 and the capacitor C5 are connected in parallel with the capacitor C1 and the C2, and the capacitor C1 and the C2 are connected in series.

5. The laser automatic optical power control circuit as claimed in claim 4, characterized in that: The transistor subcircuit includes an NPN transistor Q1, a resistor R5, a current limiting resistor R7, a filter capacitor C9, a filter capacitor C16, a current limiting resistor R9, a current limiting resistor R10, a reverse light emitting diode D1, a forward diode D2, a filter capacitor C11, a filter capacitor C12, a filter capacitor C13, a filter capacitor C18 and a magnetic bead L1; the base of the NPN transistor Q1 is connected to the resistor R5 to the output end of the operational amplifier integrator U2A; the emitter of the NPN transistor Q1 is connected to the current limiting resistor R 7 to -5V, the -5V is connected in series with the filter capacitor C9 and the filter capacitor C16; the collector of the NPN transistor Q1 is connected in series with the current limiting resistor R9 and the current limiting resistor R10, the current limiting resistor R10 is connected to the reverse light emitting diode D1, the forward diode D2, the filter capacitor C11, the filter capacitor C12, the filter capacitor C13 and the filter capacitor C18, and is connected to the magnetic bead L1, and the magnetic bead L1 is connected to the laser bias voltage supply terminal LD_BIA.

6. A method for controlling a laser automatic optical power control circuit, used in the laser automatic optical power control circuit according to any one of claims 1 to 5, characterized in that: The following steps are involved: Determine the resistance value of resistor R11 according to the maximum output optical power of the laser and the responsiveness of the laser backlight detector; Determine the resistance values ​​of the current limiting resistors R7, R9 and R10 according to the maximum output optical power of the laser, the bias voltage when the laser has the maximum output optical power and the minimum collector-emitter voltage when the transistor operates in the amplification region; Based on the resistance value, the voltage value of the potentiometer R2 is changed to adjust the output optical power of the laser to the target value.

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