Optical signal gain adjusting circuit, optical power detection system and laser

Abstract

The utility model relates to an optical signal gain adjusting circuit, an optical power detection system and a laser. The circuit comprises a photoelectric sensor which is used for collecting a laser signal of a laser and converting the laser signal into a current signal; the pre-operation amplification unit is connected with the photoelectric sensor and is used for converting the current signal into a voltage signal; the input end of the voltage gain control unit is configured to access a gain control signal, the output end of the voltage gain control unit is connected with the control voltage input end of the variable gain amplification unit, and the voltage gain control unit is used for converting the gain control signal into a voltage gain control signal; and the input end of the variable gain amplification unit is connected with the output end of the pre-operation amplification unit, and the variable gain amplification unit is used for performing gain regulation and control on the voltage signal output by the pre-operation amplification unit under the control of the gain control signal. By adopting the circuit, the accuracy of laser signal processing can be improved.

Description

Technical Field

[0001] This application relates to the field of laser technology, and in particular to an optical signal gain adjustment circuit, an optical power detection system, and a laser. Background Technology

[0002] With the development of laser technology, optical power feedback modules have emerged. These modules can sample the output of the laser and perform power detection, thereby providing power feedback.

[0003] Traditional optical power feedback modules are designed for lasers with fixed wavelengths. After the photodiode receives the laser signal, it undergoes amplification, filtering, and other signal processing before sampling and calculation, and then outputs the optical power value for feedback. However, when outputting lasers of different wavelengths, the signal processing stage can experience signal truncation or low signal-to-noise ratio due to the change in laser wavelength. This leads to inaccurate or distorted signal processing results, which in turn results in inaccurate or distorted signal sampling. Utility Model Content

[0004] Therefore, it is necessary to provide an optical signal gain adjustment circuit, an optical power detection system, and a laser that can improve the accuracy of laser signal processing, in order to address the above-mentioned technical problems.

[0005] In a first aspect, an optical signal gain adjustment circuit is provided, which is applied to a laser, and the circuit includes:

[0006] Photoelectric sensors are used to collect laser signals from lasers and convert them into current signals.

[0007] The preamplifier unit is connected to the photoelectric sensor and is used to convert the current signal into a voltage signal.

[0008] The voltage gain control unit has its input terminal configured to receive a gain control signal, and its output terminal connected to the control voltage input terminal of the variable gain amplifier unit, which is used to convert the gain control signal into a voltage gain control signal.

[0009] The variable gain amplifier unit has its input connected to the output of the preamplifier operational amplifier unit and is used to adjust the gain of the voltage signal output by the preamplifier operational amplifier unit under the control of the gain control signal.

[0010] In some embodiments, the preamplifier unit includes a transimpedance operational amplifier, a first capacitor element, and a first resistor element; wherein...

[0011] The first terminal of the first capacitor element is connected to the output terminal of the photoelectric sensor, the first terminal of the first resistor element, and the inverting input terminal of the transimpedance operational amplifier; and

[0012] The second terminal of the first capacitor element is connected to the second terminal of the first resistor element and the feedback input terminal of the transimpedance operational amplifier.

[0013] In some embodiments, the circuit further includes:

[0014] The dark current compensation unit is connected between the non-inverting input terminal and the output terminal of the preamplifier operational amplifier unit, and is used to inversely compensate for the dark current generated at the non-inverting input terminal of the preamplifier operational amplifier unit.

[0015] In some embodiments, the dark current compensation unit includes: an operational amplifier element and a second capacitor element; wherein...

[0016] The inverting input terminal of the operational amplifier element is connected to the output terminal of the preamplifier unit and the first terminal of the second capacitor element;

[0017] The output terminal of the operational amplifier element is connected to the non-inverting input terminal of the preamplifier unit and the second terminal of the second capacitor element; and

[0018] The non-inverting input terminal of the operational amplifier element is grounded.

[0019] In some embodiments, the circuit further includes a first diode element and a second diode element; wherein,

[0020] The cathode of the first diode is connected to the anode of the second diode and the inverting input of the preamplifier unit; and

[0021] The positive terminal of the first diode element is connected to the negative terminal of the second diode element and grounded.

[0022] In some embodiments, the voltage gain control unit is implemented using an inverting amplifier circuit.

[0023] In some embodiments, the circuit further includes:

[0024] The filtering unit is connected to the output of the variable gain amplifier unit and is used to filter the signal output by the variable gain amplifier unit.

[0025] In some embodiments, the filtering unit includes a multiple feedback Bessel filter.

[0026] Secondly, an optical power detection system is provided, the system comprising:

[0027] The optical signal gain adjustment circuit according to any one of the first aspects;

[0028] The microcontroller unit is connected to the optical signal gain adjustment circuit. The microcontroller unit is used to send gain control signals to the optical signal gain adjustment circuit and to collect the signals output by the optical signal gain adjustment circuit for power detection.

[0029] Thirdly, a laser is also provided, including an optical power detection system according to the second aspect.

[0030] The aforementioned optical signal gain adjustment circuit, optical power detection system, and laser can controllably attenuate or amplify the amplitude of the voltage signal converted from the optical signal acquired by the photoelectric sensor within a certain range. For voltage signals with large amplitudes, attenuation adjustment can be performed to prevent excessive gain from causing signal clipping, which could lead to a decrease in signal-to-noise ratio, signal incompleteness, or signal distortion. For voltage signals with small amplitudes, the signal can be amplified, thereby reducing the impact of quantization errors in the acquisition link on the acquired value and improving the accuracy of signal processing. Moreover, even when the laser requires laser input of different wavelengths, it can automatically adjust the gain of signals with different amplitudes due to changes in laser wavelength, thus ensuring the accuracy of signal processing and, consequently, the accuracy of signal sampling in the laser power detection system. Attached Figure Description

[0031] Figure 1 This is a structural framework diagram of the optical power detection system in some embodiments;

[0032] Figure 2 This is a structural framework diagram of the optical signal gain adjustment circuit in some embodiments;

[0033] Figure 3 This is a structural framework diagram of the optical signal gain adjustment circuit in some other embodiments;

[0034] Figure 4 This is a schematic diagram of the preamplifier unit and dark current compensation unit of the optical signal gain adjustment circuit in some embodiments;

[0035] Figure 5 This is a schematic diagram of the voltage gain control unit in some embodiments;

[0036] Figure 6 This is a schematic diagram of the structure of the variable gain amplifier unit in some embodiments. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0038] In some embodiments, this application provides an optical signal gain adjustment circuit 100, which can be applied to, for example... Figure 1 The optical power detection system 10 of the laser shown may include:

[0039] The optical signal gain adjustment circuit 100 can adjust the gain of the laser signal emitted by the laser and then output it to the microcontroller unit 200.

[0040] The microcontroller unit 200 is connected to the optical signal gain adjustment circuit 100. The microcontroller unit 200 is used to send gain control signals to the optical signal gain adjustment circuit 100 and to collect the signals output by the optical signal gain adjustment circuit 100 for power detection.

[0041] The optical power detection system 10 of this application includes an optical signal gain adjustment circuit 100. Since the optical signal gain adjustment circuit 100 of this application can improve the accuracy of optical signal processing, it can improve the accuracy of signal sampling and optical power detection of the optical power detection system. The structure of the optical signal gain adjustment circuit 100 of this application and how to improve the accuracy of optical signal processing will be described in detail below.

[0042] The optical signal gain adjustment circuit 100 involved in this application will now be described in further detail, with reference to... Figure 2 As shown, Figure 2 This is a schematic diagram of the circuit structure of the optical signal gain adjustment circuit 100 in some embodiments. Specifically, the optical signal gain adjustment circuit 100 may include:

[0043] The photoelectric sensor 101 is used to collect the laser signal from the laser and convert the laser signal into a current signal.

[0044] The preamplifier unit 102 is connected to the photoelectric sensor 101 and is used to convert the current signal input by the photoelectric sensor 101 into a voltage signal.

[0045] The voltage gain control unit 103 has its input terminal configured to receive a gain control signal, and its output terminal connected to the control voltage input terminal of the variable gain amplifier unit 104, for converting the gain control signal into a voltage gain control signal.

[0046] The variable gain amplifier unit 104 has its input terminal connected to the output terminal of the preamplifier operational amplifier unit 102, and is used to adjust the gain of the voltage signal output by the preamplifier operational amplifier unit 102 under the control of the gain control signal.

[0047] More specifically, after the laser emits a laser beam, the photoelectric sensor 101, when irradiated by the laser, converts the laser signal into a weak current signal OP_IN. The magnitude of this current signal OP_IN changes proportionally with the intensity of the laser signal. For example, the photoelectric sensor 101 may include, but is not limited to, a photodiode (PD), an organic photodiode (OPD), etc.

[0048] Then, the current signal OP_IN can be connected to a current-input type preamplifier 102. The preamplifier 102 converts the weak current signal OP_IN generated by the photoelectric sensor 101 into a voltage signal DC_COM. The magnitude of the voltage signal DC_COM is proportional to the magnitude of the input current signal OP_IN, and the specific proportion can be adjusted according to the actual application scenario. Subsequently, the voltage signal DC_COM is input to the input terminal of the variable gain amplifier unit 104.

[0049] The gain control signal GAIN_CONT_A output from the gain control pin of the MCU (Microcontroller Unit) can only be a positive amplitude signal. Therefore, the voltage gain control unit 103 can amplify the gain control signal GAIN_CONT_A into a voltage gain control signal GAIN_CONT_B that can control the variable gain amplifier unit 104 to adjust the gain value within a certain range.

[0050] For example, the gain control signal GAIN_CONT_A, after being inverted and amplified by the voltage gain control unit 103, can output a voltage gain control signal GAIN_CONT_B of, for example, 0 to -2V. This enables the variable gain amplifier unit 104 within the range of 0 to -2V, allowing it to linearly adjust the gain of the input voltage signal DC_COM within, for example, a range of -40dB to +40dB. In other embodiments, the inverting amplification factor of the voltage gain control unit 103 can be adjusted according to actual needs, thereby adjusting the range of the voltage gain control signal GAIN_CONT_B, and thus adjusting the magnitude of the linear gain change.

[0051] The optical signal gain adjustment circuit 100 described above can controllably attenuate or amplify the amplitude of the input voltage signal DC_COM within a certain range, based on the magnitude of the amplitude. For voltage signals DC_COM with large amplitudes, attenuation adjustment can be performed to prevent excessive gain from truncating the signal, which could lead to a decrease in signal-to-noise ratio, signal incompleteness, or signal distortion. For voltage signals DC_COM with small amplitudes, the signal can be amplified to the maximum range allowed by the ADC (Analog to Digital Converter), thereby reducing the impact of the ADC's own quantization error on the acquired value and improving the accuracy of signal processing. Therefore, even when the laser requires laser input of different wavelengths, the gain can be automatically adjusted for signals with different amplitudes due to changes in laser wavelength, ensuring the accuracy of signal processing and, consequently, the accuracy of signal sampling in the laser power detection system.

[0052] In some embodiments, such as Figure 4 As shown, the preamplifier unit 102 may include a transimpedance operational amplifier U6, a first capacitor C1, and a first resistor R12; wherein,

[0053] The first terminal of the first capacitor C1 is connected to the output terminal of the photoelectric sensor 101 (for receiving the current signal OP_IN), the first terminal of the first resistor R12, and the inverting input terminal U6- (pin 3) of the transimpedance operational amplifier U6; and

[0054] The second terminal of the first capacitor element C1 is connected to the second terminal of the first resistor element R12 and the feedback input terminal U6-FB (pin 1) of the transimpedance operational amplifier U6.

[0055] For example, the transimpedance operational amplifier U6 can be implemented using an OPA859 amplifier, but it is not limited to this and can be flexibly selected according to requirements. In this embodiment, the other pins of the transimpedance operational amplifier U6 can be adaptively configured according to the actual application. For example, refer to... Figure 4 The configuration shown is not limited to this.

[0056] In this embodiment, the preamplifier unit 102 built based on the transimpedance operational amplifier U6, compared with a conventional current-mode operational amplifier, can improve the signal-to-noise ratio of the output signal. This is because the main noise value originates solely from the thermal noise inherent in the first resistor element R12, while in a conventional current-mode operational amplifier, the noise value in the signal increases proportionally after proportional gain amplification. Furthermore, in some embodiments, when MCU-based gain control is not possible via the gain control signal, the signal gain can be changed by adjusting the resistance value of the first resistor element R12.

[0057] In some embodiments, reference Figure 4 As shown, the optical signal gain adjustment circuit 100 also includes:

[0058] Dark current compensation unit 105 is connected between the non-inverting input terminal and the output terminal of the preamplifier operational amplifier unit 102, and is used to reverse compensate for the dark current generated at the non-inverting input terminal of the preamplifier operational amplifier unit 102.

[0059] In this embodiment, since the photoelectric sensor 101 still has a weak current flowing out in a completely dark environment, i.e., dark current, a dark current compensation unit 105 is set at the input end of the preamplifier unit 102 to perform dark current compensation, thereby preventing the dark current from affecting the output result and improving the accuracy of the output signal.

[0060] In some embodiments, continue to refer to Figure 4 As shown, the dark current compensation unit 105 may include: an operational amplifier element U7B and a second capacitor element C4; wherein,

[0061] The inverting input terminal U7B- (pin 6) of operational amplifier element U7B is connected to the output terminal of preamplifier unit 102 (e.g., pin 6 of U6) and the first terminal of second capacitor element C4.

[0062] The output terminal (pin 7) of operational amplifier component U7B is connected to the non-inverting input terminal (pin 4 of U6) of preamplifier unit 102 and the second terminal of second capacitor component C4;

[0063] The non-inverting input terminal U7B+ (pin 5) of operational amplifier component U7B is grounded.

[0064] In this embodiment, an inverse compensation circuit constructed using an operational amplifier and a capacitor is used to compensate for the dark current of the photoelectric sensor 101. Through the combined action of the operational amplifier element U7B and the second capacitor element C4, the current (DC_COM_IN) at the non-inverting input terminal (pin 4 of U6) of the preamplifier operational amplifier unit 102 is compensated to 0 or close to 0. Figure 3 This is only an example; components such as R13, R14, and R15 can be adjusted according to actual needs.

[0065] In some embodiments, continue to refer to Figure 4 As shown, the optical signal gain adjustment circuit 100 may further include a first diode element D3 and a second diode element D4; wherein,

[0066] The negative terminal D3- of the first diode element D3 is connected to the positive terminal D4+ of the second diode element D4 and the inverting input terminal (pin 3 of U6) of the preamplifier unit 102; and the positive terminal D3+ of the first diode element D3 is connected to the negative terminal D4- of the second diode element D4 and grounded to GND.

[0067] In this embodiment, by adding a first diode element D3 and a second diode element D4 to the inverting input terminal of the preamplifier unit 102, excessive voltage can be prevented from being applied to the inverting input terminal of the preamplifier unit 102, which can play a certain role in voltage division and current limiting, thereby improving the stability of the current.

[0068] In some embodiments, the voltage gain control unit 103 may be implemented using an inverting amplifier circuit. (See reference...) Figure 5 and Figure 6 As shown, Figure 5 A schematic diagram of the voltage gain control unit 103 in some embodiments is shown. Figure 6 A schematic diagram of the structure of the variable gain amplifier unit 104 in some embodiments is shown.

[0069] Among them, reference Figure 5 As shown, an operational amplifier U4B can be used in conjunction with resistors R9, R10, R11 and electrolytic capacitor CE1 to construct an inverting amplifier circuit as a voltage gain control unit 103. In practical applications, the structure of the inverting amplifier circuit or the types or number of components can be adjusted according to requirements.

[0070] Among them, reference Figure 6 As shown, the variable gain amplifier unit 104 can employ, for example... Figure 5 The variable gain amplifier U2 shown is implemented as described.

[0071] In the above embodiment, the voltage signal DC_COM output after passing through the preamplifier unit 102 is input to the inverting input terminal U2- (pin 8) of the variable gain amplifier U2. The gain control signal GAIN_CONT_A output by the MCU controls the gain value of the input voltage signal DC_COM within a certain range. The voltage gain control unit 103 amplifies the gain control signal GAIN_CONT_A in reverse and outputs a voltage gain control signal GAIN_CONT_B that meets the voltage control requirements of the variable gain amplifier U2. The voltage gain control signal GAIN_CONT_B is input to the control voltage input terminal Vc of the variable gain amplifier U2, so that the variable gain amplifier U2 controls the gain value of the voltage signal DC_COM within a certain range under the control of the voltage gain control signal GAIN_CONT_B.

[0072] In some embodiments, reference Figure 3 As shown, the optical signal gain adjustment circuit 100 may further include:

[0073] The filtering unit 106 can be connected to the output terminal of the variable gain amplifier unit 104 and is used to filter the signal output by the variable gain amplifier unit 104.

[0074] In this embodiment, the signal with gain adjustment can be further fed into the filtering unit 106 for filtering processing, thereby further filtering out noise in the signal.

[0075] In some embodiments, the filtering unit 106 includes an MFB (Multiple Feedback) Bessel filter. The MFB Bessel filter is chosen because it has excellent linear phase characteristics and a relatively flat group delay characteristic within the passband, enabling it to transmit wide-spectrum signals such as square waves and triangular waves without distortion. Furthermore, the MFB active filter topology has low sensitivity to components, and its amplitude-frequency response curve is less prone to ripple at high Q values. Both low-pass and high-pass filters can employ fourth-order topology circuits, resulting in a more accurate output signal PD_OUT.

[0076] In some embodiments, this application also provides a laser, which may include the optical power detection system 10 of the above embodiments. For a detailed description of the optical power detection system 10, please refer to the above text; it will not be repeated here. Using the laser provided in this application, when the laser requires laser input of different wavelengths, it can automatically adjust the gain of the signal with different amplitude values ​​due to changes in laser wavelength, thereby ensuring the accuracy of optical signal processing, and further ensuring the accuracy of signal sampling in the laser power detection system, improving the accuracy of laser optical power feedback, and ensuring stable and safe laser power output.

[0077] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An optical signal gain adjustment circuit, characterized in that, The circuit is applied to a laser, and the circuit includes: A photoelectric sensor, used to acquire the laser signal from the laser and convert the laser signal into a current signal; A preamplifier unit, which is connected to the photoelectric sensor, is used to convert the current signal into a voltage signal; A voltage gain control unit, wherein the input terminal of the voltage gain control unit is configured to receive a gain control signal, and the output terminal of the voltage gain control unit is connected to the control voltage input terminal of the variable gain amplifier unit, for converting the gain control signal into a voltage gain control signal; A variable gain amplifier unit, the input of which is connected to the output of the preamplifier operational amplifier unit, is used to adjust the gain of the voltage signal output by the preamplifier operational amplifier unit under the control of the gain control signal.

2. The circuit according to claim 1, characterized in that, The preamplifier operational amplifier unit includes a transimpedance operational amplifier, a first capacitor element, and a first resistor element; wherein... The first end of the first capacitor element is connected to the output terminal of the photoelectric sensor, the first end of the first resistor element, and the inverting input terminal of the transimpedance operational amplifier; and The second end of the first capacitor element is connected to the second end of the first resistor element and the feedback input terminal of the transimpedance operational amplifier.

3. The circuit according to claim 1, characterized in that, The circuit also includes: A dark current compensation unit is connected between the non-inverting input terminal and the output terminal of the preamplifier operational amplifier unit, and is used to reverse compensate for the dark current generated at the non-inverting input terminal of the preamplifier operational amplifier unit.

4. The circuit according to claim 3, characterized in that, The dark current compensation unit includes: an operational amplifier element and a second capacitor element; wherein... The inverting input terminal of the operational amplifier element is connected to the output terminal of the preamplifier unit and the first terminal of the second capacitor element; The output terminal of the operational amplifier element is connected to the non-inverting input terminal of the preamplifier unit and the second terminal of the second capacitor element; and The non-inverting input terminal of the operational amplifier element is grounded.

5. The circuit according to claim 1, characterized in that, The circuit further includes a first diode element and a second diode element; wherein... The cathode of the first diode element is connected to the anode of the second diode element and the inverting input of the preamplifier unit; and The positive terminal of the first diode element is connected to the negative terminal of the second diode element and grounded.

6. The circuit according to claim 1, characterized in that, The voltage gain control unit is implemented using an inverting amplifier circuit.

7. The circuit according to claim 1, characterized in that, The circuit also includes: A filtering unit is connected to the output terminal of the variable gain amplifier unit and is used to filter the signal output by the variable gain amplifier unit.

8. The circuit according to claim 7, characterized in that, The filtering unit includes a multiple feedback Bessel filter.

9. An optical power detection system, characterized in that, The system includes: The optical signal gain adjustment circuit according to any one of claims 1 to 8; A microcontroller unit is connected to the optical signal gain adjustment circuit. The microcontroller unit is used to send a gain control signal to the optical signal gain adjustment circuit and to collect the signal output by the optical signal gain adjustment circuit for power detection.

10. A laser, characterized in that, Including the optical power detection system according to claim 9.

Images