Laser power detection control circuit

Abstract

The utility model discloses a laser power detection control circuit, and solves the technical problem of inaccurate detection result caused by unstable optical power when a laser detects optical loss of an optical fiber in the prior art. Comprising a main control chip, a laser driving circuit, a laser and a power detection circuit, the main control chip is connected with the laser driving circuit, the laser driving circuit is connected with the laser, and the power detection circuit is connected with the laser and the main control chip; the power detection circuit comprises a photoelectric conversion circuit which is connected with the laser; and the amplification circuit is connected with the photoelectric conversion circuit and the main control chip. According to the laser power detection control circuit, the backward light power of the laser is detected, the driving current is adjusted in real time to enable the laser to provide a stable light source, the light source stabilizing effect of the laser is effectively improved, and the circuit is low in implementation cost and high in practicability. The utility model can be widely applied to the technical field of lasers.

Description

Technical Field

[0001] The utility model relates to the technical field of lasers, in particular to a laser power detection control circuit. Background Art

[0002] In the function of the optical time domain reflectometer (OTDR), the optical loss value of the optical fiber can be tested by emitting a light source through a laser. To ensure the accuracy of the measured data, the laser needs to emit a stable light source. The conventional method for stabilizing the laser light source is generally to control the working current of the laser through a current-limiting resistor, thereby controlling the output of the laser. However, in actual operation, the current of the laser is easily affected by the power supply voltage and ambient temperature, resulting in floating changes in the output power. The laser cannot truly provide a stable light source, which affects the actual measurement of the optical loss value of the optical fiber and affects the use effect. Utility Model Content

[0003] The utility model aims at the shortcomings and deficiencies in the prior art and provides a laser power detection control circuit. By detecting the backward optical power of the laser, the driving current is adjusted in real time so that the laser provides a stable light source. The circuit has low implementation cost and strong practicality.

[0004] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0005] The present application provides a laser power detection control circuit, comprising a main control chip, a laser driving circuit, a laser and a power detection circuit, wherein the main control chip is connected to the laser driving circuit, the laser driving circuit is connected to the laser, and the power detection circuit is connected to the laser and the main control chip respectively;

[0006] The power detection circuit comprises:

[0007] A photoelectric conversion circuit, wherein the photoelectric conversion circuit is connected to the laser;

[0008] An amplifier circuit is connected to the photoelectric conversion circuit and the main control chip.

[0009] Furthermore, the photoelectric conversion circuit includes a photoelectric sensor, an input end of the photoelectric sensor is connected to the backward light of the laser, and an output end of the photoelectric sensor is connected to the amplification circuit.

[0010] Furthermore, the amplifying circuit includes an IV conversion circuit and a signal amplifying circuit.

[0011] Furthermore, it also includes an AD conversion circuit, the input end of the AD conversion circuit is connected to the amplification circuit, and the output end of the AD conversion circuit is connected to the main control chip.

[0012] Furthermore, the signal amplifying circuit includes a primary signal amplifying circuit and a secondary signal amplifying circuit.

[0013] Furthermore, the amplification circuit includes an operational amplifier chip, which integrates the IV conversion circuit and the signal amplification circuit, an enable pin of the operational amplifier chip is connected to the control pin of the main control chip, an inverting input pin of the operational amplifier chip is connected to the photoelectric conversion circuit, and an output pin of the operational amplifier chip is connected to the AD conversion circuit.

[0014] Furthermore, the inverting input pin of the operational amplifier chip is connected to the output pin via a feedback resistor, and the feedback resistor is connected in parallel with a feedback capacitor.

[0015] Furthermore, the non-inverting input pin of the operational amplifier chip is grounded through a 0R resistor, and a filter capacitor is connected in parallel to the 0R resistor.

[0016] Furthermore, the main control chip includes a calculation unit, which is used to compare the difference between the actual optical power of the laser measured by the power detection circuit and the preset optical power, and output instructions to the laser driving circuit according to the difference to adjust the output optical power of the laser.

[0017] The utility model has the following beneficial effects:

[0018] The laser power detection control circuit of the utility model collects the backward light signal of the laser and converts it into an electrical signal, converts the electrical signal into an electrical signal through an amplifier circuit and amplifies it, and then converts the voltage signal through an AD conversion circuit to a main control chip to calculate the actual optical power value. By comparing the actual optical power value with the preset optical power value, the main control chip controls the laser drive circuit to change the output current of the laser, thereby adjusting the output power of the laser. Through this circuit structure, the actual output optical power of the laser can be detected in real time, adjusted in time, and the stability of the laser light source output can be guaranteed. When performing optical fiber optical loss value detection, the accuracy of the detection data can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a laser power detection control circuit shown in an embodiment of the utility model;

[0020] Figure 2 The figure is a schematic diagram of the circuit structure of an operational amplifier chip in a laser power detection and control circuit shown in an embodiment of the utility model.

[0021] In the figure: 1. Main control chip; 2. Laser driving circuit; 3. Laser; 4. Photoelectric conversion circuit; 5. Amplification circuit; 6. AD conversion circuit. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0023] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Example 1

[0025] See also Figure 1-2 , the utility model provides a technical solution:

[0026] like Figure 1 As shown, the utility model provides a laser power detection control circuit, including a main control chip 1, a laser driving circuit 2, a laser 3 and a power detection circuit, the main control chip 1 is connected to the laser driving circuit 2, the laser driving circuit 2 is connected to the laser 3, and the power detection circuit is respectively connected to the laser 3 and the main control chip 1.

[0027] The power detection circuit comprises: a photoelectric conversion circuit 4 , which is connected to the laser 3 ; and an amplifier circuit 5 , which is connected to the photoelectric conversion circuit 4 and the main control chip 1 .

[0028] Semiconductor lasers, also known as laser diodes (LD), are devices that use certain semiconductor materials as working materials to produce stimulated emission. Semiconductor lasers include FP lasers and DFB lasers. Compared with DFB lasers, FP lasers have a wider spectrum and are suitable for rates within 1.25G. In this embodiment, laser 3 uses FP lasers.

[0029] The laser driving circuit 2 provides driving current for the laser 3. The laser 3 works to emit light. The power detection circuit detects the actual power of the laser 3 light source and transmits the power data to the main control chip 1. The main control chip 1 adjusts the output power of the laser 3 by adjusting the output current of the laser driving circuit 2. Through this circuit structure, the actual output optical power of the laser 3 can be detected in real time and adjusted in time to ensure the stability of the output of the laser 3 light source. When the optical loss value of the optical fiber is detected, the accuracy of the detection data is effectively improved.

[0030] Furthermore, the main control chip 1 includes a calculation unit, which is used to compare the difference between the actual optical power of the laser 3 measured by the power detection circuit and the preset optical power, and output instructions to the laser driving circuit 2 to adjust the output optical power of the laser 3 according to the difference.

[0031] Furthermore, it also includes an AD conversion circuit 6 , an input end of the AD conversion circuit 6 is connected to the amplification circuit 5 , and an output end of the AD conversion circuit 6 is connected to the main control chip 1 .

[0032] In this embodiment, the main control chip 1 can be a GD32F4 series MCU, and the AD conversion circuit 6 is integrated in the main control chip 1. -M4 core, processor main frequency 240MHz, can support embedded applications with higher algorithm complexity, fast real-time processing capability, and large storage capacity. In addition, the GD32F4 series has rich peripheral resource characteristics, providing 4 USARTs and 4 UARTs, 3 I2Cs, 6 SPIs, 2 I2Ss, 2 CAN2.0Bs, 1 SDIO interface, 1 10 / 100M Ethernet controller, and supports USB2.0 FS and HS communications, equipped with 3 ADCs. Used in multi-functional electronic devices that apply lasers, it can effectively meet the equipment operation requirements.

[0033] The power signal measured by the power detection circuit is connected to the ADC pin of the main control chip 1 for conversion, and then the actual optical power value is obtained by the calculation unit.

[0034] In some embodiments of the present application, the AD conversion circuit 6 may include a separate A / D chip, and the voltage signal is converted by the A / D chip and then sent to the main control chip 1.

[0035] Furthermore, the photoelectric conversion circuit 4 includes a photoelectric sensor, an input end of the photoelectric sensor is connected to the backward light of the laser 3 , and an output end of the photoelectric sensor is connected to the amplifier circuit 5 .

[0036] In this embodiment, the photoelectric sensor is a PD photodiode. The photoelectric tube generates current by absorbing light signals through the photosensitive element, and amplifies the electrical signals through the electron tube to realize the conversion of light signals into electrical signals. The peripheral circuit of the PD photodiode is simple and the use cost is low. The PD photodiode absorbs the backward light of the laser 3 and converts it into an electrical signal and then transmits it to the amplifier circuit 5.

[0037] The amplifier circuit 5 includes an IV conversion circuit and a signal amplifier circuit. The IV conversion circuit is used to convert the electrical signal of the photoelectric sensor into a voltage signal. Since the power detection signal of the laser 3 is small, the voltage signal is amplified by the signal amplifier circuit and then transmitted to the main control chip 1 for processing.

[0038] Furthermore, the amplification circuit 5 includes an operational amplifier chip, which integrates an IV conversion circuit and a signal amplification circuit. The enable pin of the operational amplifier chip is connected to the control pin of the main control chip 1, the inverting input pin of the operational amplifier chip is connected to the photoelectric conversion circuit 4, and the output pin of the operational amplifier chip is connected to the AD conversion circuit 6.

[0039] Specifically, Figure 2 As shown, in this embodiment, the operational amplifier chip model can be RS8751, which has a unit gain stability and can operate in the full temperature range of -40°C to +125°C.

[0040] The pin1 output pin of the operational amplifier chip is connected to the PD_ADC pin of the main control chip 1, the pin2 pin is connected to the power ground, the pin4 inverting input pin is connected to the PD- pin of the PD photodiode, the pin5 enable pin is connected to the LD_CW_EN pin of the main control chip 1, and the pin6 power pin is connected to the power supply VCC_LD to power it.

[0041] Furthermore, the inverting input pin of the operational amplifier chip is connected to the output pin via a feedback resistor, and the feedback resistor is connected in parallel with a feedback capacitor.

[0042] like Figure 2 As shown, a feedback resistor R23 is connected between the pin3 inverting input pin and the pin1 output pin of the operational amplifier chip, and a feedback capacitor C4 is connected in parallel with the feedback resistor R23 to achieve the function of amplifying the signal.

[0043] Furthermore, the non-inverting input pin of the operational amplifier chip is grounded through a 0R resistor, and a filter capacitor is connected in parallel with the 0R resistor.

[0044] like Figure 2 As shown, the pin3 positive input pin of the operational amplifier chip is grounded through a 0R resistor R25, and a filter capacitor C5 is connected in parallel with the 0R resistor R25 to achieve noise reduction.

[0045] The working principle of this embodiment:

[0046] When the laser 3 provides a light source to measure the optical loss value of the optical fiber, the photoelectric sensor of the photoelectric conversion circuit 4 absorbs the backward light of the laser 3 and converts it into an electrical signal. The photoelectric sensor transmits the electrical signal to the operational amplifier chip through the circuit. The operational amplifier chip converts the electrical signal into a voltage signal and transmits it to the main control chip 1 after amplification. The main control chip 1 converts the voltage signal and calculates the actual optical power value of the laser 3. By comparing the actual optical power value with the preset optical power value, if the actual power value read is less than the preset optical power value, the main control chip 1 controls the laser driving circuit 2 to increase the output current of the laser 3, thereby increasing the output power. If the actual power value read is greater than the preset optical power value, the main control chip 1 controls the laser driving circuit 2 to reduce the output current of the laser 3, thereby reducing the output power.

[0047] Example 2

[0048] Different from the first embodiment, the signal amplifying circuit in this embodiment includes a primary signal amplifying circuit and a secondary signal amplifying circuit.

[0049] The primary signal amplification circuit and the secondary signal amplification circuit are proportional amplification circuits, which are used to amplify the power signal step by step to improve the sensitivity of detection. In this embodiment, the multi-stage signal amplification circuit can use a transimpedance amplifier chip of model OPA687.

[0050] It should be noted that the terms used above are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0051] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0052] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0053] The above is only a preferred specific implementation manner of the present invention, and the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A laser power detection control circuit, characterized in that: Comprising a main control chip (1), a laser driving circuit (2), a laser (3) and a power detection circuit, wherein the main control chip (1) is connected to the laser driving circuit (2), the laser driving circuit (2) is connected to the laser (3), and the power detection circuit is respectively connected to the laser (3) and the main control chip (1); The power detection circuit comprises: A photoelectric conversion circuit (4), wherein the photoelectric conversion circuit (4) is connected to the laser (3); An amplifier circuit (5), wherein the amplifier circuit (5) is connected to the photoelectric conversion circuit (4) and the main control chip (1).

2. The laser power detection control circuit according to claim 1, characterized in that: The photoelectric conversion circuit (4) comprises a photoelectric sensor, the input end of the photoelectric sensor is connected to the backward light of the laser (3), and the output end of the photoelectric sensor is connected to the amplification circuit (5).

3. The laser power detection control circuit according to claim 2, characterized in that: The amplifying circuit (5) comprises an IV conversion circuit and a signal amplifying circuit.

4. The laser power detection control circuit according to claim 3, characterized in that: It also comprises an AD conversion circuit (6), wherein an input end of the AD conversion circuit (6) is connected to the amplification circuit (5), and an output end of the AD conversion circuit (6) is connected to the main control chip (1).

5. The laser power detection control circuit according to claim 3, characterized in that: The signal amplifying circuit includes a primary signal amplifying circuit and a secondary signal amplifying circuit.

6. The laser power detection control circuit according to claim 4, characterized in that: The amplifier circuit (5) comprises an operational amplifier chip, the operational amplifier chip integrating the IV conversion circuit and the signal amplifier circuit, the enable pin of the operational amplifier chip being connected to the control pin of the main control chip (1), the inverting input pin of the operational amplifier chip being connected to the photoelectric conversion circuit (4), and the output pin of the operational amplifier chip being connected to the AD conversion circuit (6).

7. The laser power detection control circuit according to claim 6, characterized in that: The inverting input pin of the operational amplifier chip is connected to the output pin via a feedback resistor, and the feedback resistor is connected in parallel with a feedback capacitor.

8. The laser power detection control circuit according to claim 6, characterized in that: The non-inverting input pin of the operational amplifier chip is grounded through a 0R resistor, and a filter capacitor is connected in parallel to the 0R resistor.

9. The laser power detection control circuit according to claim 1, characterized in that: The main control chip (1) comprises a calculation unit, which is used to compare the difference between the actual optical power of the laser (3) measured by the power detection circuit and the preset optical power, and output instructions to the laser drive circuit (2) according to the difference to adjust the output optical power of the laser (3).

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