A device for detecting weak light by resonant balanced zero-beat

Abstract

The present invention discloses a device for resonant balanced zero-beat detection of weak light, comprising a first photodiode, a second photodiode, a transimpedance amplifier circuit, a frequency-selective inductor, a frequency-selective capacitor, a secondary voltage amplifier circuit, a filter resistor, a filter capacitor and a direct current in-phase proportional amplifier circuit; the photoelectric detection device responds only at the resonant frequency, thus avoiding the limitation of the gain-bandwidth product of the amplifier chip and also having high gain at high frequencies.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectric detectors, and in particular to a device for detecting weak light by resonant balanced zero-beat detection. Background Art

[0002] Quantum measurement connects the quantum world and the classical world, and plays an important role in quantum technologies such as quantum sensing, cryptography, and quantum computing. Photoelectric detection is one of the ideal quantum measurement methods, which can achieve quantum efficiency close to 100% and high signal-to-noise ratio, and is therefore used in gravitational wave detection, quantum enhanced optical phase tracking, compressed state detection, quantum state reconstruction, and measurement-based quantum operations. Photoelectric detection can be divided into direct detection and coherent detection according to the detection method. Coherent detection can detect information such as the frequency, amplitude, and phase of light, and is more widely used. Coherent detection can be divided into zero-beat detection and differential beat detection according to the difference between the signal light and the local light frequency. Zero-beat detection can detect non-classical light fields such as compressed states, and is of great value in detecting weak light.

[0003] Since quantum noise cannot be eliminated directly physically, weak light detection is difficult to achieve. Experimental studies in recent decades have shown that squeezed state light fields can break through the standard quantum limit, so the detection of squeezed states is particularly important, and balanced zero-beat detection is an important technical means to detect quantum noise in squeezed state light fields. At the same time, signal-to-noise ratio and saturation power have become important parameters that restrict balanced zero-beat detection in low-frequency bands. The bandwidth of traditional broadband zero-beat detectors used in quantum optics is usually less than 100MHz due to the terminal capacitance of the photodiode, while the resonant structure can achieve high transimpedance gain and good signal-to-noise ratio. In addition, balanced zero-beat detection usually requires a local optical power that is at least one order of magnitude higher than the signal power. When the signal power itself is very high, adding a higher-power local light can easily saturate the detector.

[0004] The signal-to-noise ratio of existing balanced zero-beat detectors is mostly not very high, especially in the high-frequency region. Limited by the gain-bandwidth product, the bandwidth of ordinary broadband balanced zero-beat detectors increases as the frequency domain increases, but the gain gradually decreases. A few higher values ​​are measured based on high input optical power, and the actual use effect is not very good. Summary of the invention

[0005] In order to solve the problem of easy saturation of balanced zero-beat detectors in the above-mentioned prior art, the present invention provides a device for detecting weak light with a resonant balanced zero-beat, which can only amplify signals at specific frequencies, thereby avoiding the limitation of the gain-bandwidth product of the amplifier chip and also having high gain at high frequencies.

[0006] In order to achieve the above technical objectives, the present invention provides a resonant balanced zero-beat detection device for weak light, comprising a first photodiode, a second photodiode, a transimpedance amplifier circuit, a frequency-selective inductor, a frequency-selective capacitor, a secondary voltage amplifier circuit, a filter resistor, a filter capacitor and a DC in-phase proportional amplifier circuit;

[0007] The cathode of the first photodiode is connected to a +5V voltage, the anode of the first photodiode is connected to the cathode of the second photodiode, the connection node is a node a, and the anode of the second photodiode is connected to a -5V voltage;

[0008] The input end of the transimpedance amplifier circuit is connected to the node a, the output end of the transimpedance amplifier circuit is connected to the input end of the frequency-selective inductor, the connection node is node b, and the output end of the frequency-selective inductor is connected to the input end of the frequency-selective capacitor;

[0009] The output end of the frequency selection capacitor is connected to the reverse input end of the secondary voltage amplifier circuit, and the output end of the secondary voltage amplifier circuit is connected to the BNC head;

[0010] The input end of the filter resistor is connected to the node b, the output end of the filter resistor is connected to one end of the filter capacitor, the connection node is the node c, and the other end of the filter capacitor is grounded;

[0011] The input end of the DC in-phase proportional amplifier circuit is connected to the node c, and the output end of the DC in-phase proportional amplifier circuit is connected to another BNC head.

[0012] Optionally, the first photodiode and the second photodiode use S5971 when measuring under continuous light, and use FD100 when measuring under pulsed light.

[0013] Optionally, the transimpedance amplifier circuit includes a transimpedance amplifier chip OPA690;

[0014] Pin 4 of the transimpedance amplifier chip OPA690 is connected to the node a, pin 3 of the transimpedance amplifier chip OPA690 is grounded, pin 1 of the transimpedance amplifier chip OPA690 is connected to the node b, and pin 2 and pin 6 of the transimpedance amplifier chip OPA690 are respectively connected to the filtered -5V and +5V power supplies.

[0015] Optionally, the secondary voltage amplifier circuit includes a voltage amplifier chip LMH6624;

[0016] Pin 3 of the voltage amplifier chip LMH6624 is connected to the frequency selection capacitor, a resistor is connected between pin 2 and pin 6 of the voltage amplifier chip LMH6624, and pin 6 of the voltage amplifier chip LMH6624 is also connected to a resistor R8 output, and pin 4 and pin 7 of the voltage amplifier chip LMH6624 are respectively connected to the filtered -5V and +5V power supplies.

[0017] Optionally, the DC in-phase proportional amplifier circuit includes an amplifier chip OP27;

[0018] Pin 3 of the amplifier chip OP27 is connected to the filter resistor, a sliding resistor is connected between pin 2 and pin 3 of the amplifier chip OP27, pin 6 of the amplifier chip OP27 is connected to resistor R12, and pin 4 and pin 7 of the amplifier chip OP27 are respectively connected to the filtered -5V and +5V power supplies.

[0019] Optionally, the frequency-selective inductor and the frequency-selective capacitor form a frequency-selective circuit, and the frequency-selective circuit is used to filter out noise through a signal at a resonant frequency.

[0020] Optionally, a feedback capacitor C1, a feedback resistor R2 and a resonant inductor L1 are connected in parallel between pin 1 and pin 4 of the transimpedance amplifier chip OPA690.

[0021] Optionally, the maximum resistance of the sliding rheostat is 10 kΩ.

[0022] The present invention has the following technical effects:

[0023] The resonant balanced zero-beat detector proposed in the present invention can only amplify signals at specific frequencies, thereby avoiding the limitation of the gain-bandwidth product of the amplifier chip and also having high gain at high frequencies. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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 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 labor.

[0025] Figure 1 This is a schematic diagram of the principle of a resonant balanced zero-beat detection device for weak light according to an embodiment of the present invention;

[0026] Figure 2 This is a circuit diagram of a resonant balanced zero-beat detection device for weak light according to an embodiment of the present invention;

[0027] Figure 3This is a working principle diagram of the resonant balanced zero-beat detection device for weak light applied to photoelectric detection according to an embodiment of the present invention;

[0028] Figure 4 The output power spectrum of the resonant balanced zero-beat detection weak light device at different powers according to an embodiment of the present invention;

[0029] Figure 5 The output power spectra of the resonant balanced zero-beat detection device for weak light incident on a single photodiode and two photodiodes according to an embodiment of the present invention;

[0030] Figure 6 This is the linearity of the resonant balanced zero-beat detection device for weak light at the quantum noise peak in an embodiment of the present invention.

[0031] Explanation of the accompanying drawings: 1. First photodiode; 2. Second photodiode; 3. Transimpedance amplifier circuit; 4. Frequency-selective inductor; 5. Frequency-selective capacitor; 6. Secondary voltage amplifier circuit; 7. Filter resistor; 8. Filter capacitor; 9. DC in-phase proportional amplifier circuit; L1, resonant inductor; C1, feedback capacitor. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example

[0034] like Figure 1 As shown, the present invention discloses a device for resonant balanced zero-beat detection of weak light, comprising:

[0035] A first photodiode 1, a second photodiode 2, a transimpedance amplifier circuit 3, a frequency-selective inductor 4, a frequency-selective capacitor 5, a secondary voltage amplifier circuit 6, a filter resistor 7, a filter capacitor 8 and a DC in-phase proportional amplifier circuit 9;

[0036] The cathode of the first photodiode 1 is connected to a +5V voltage, and the anode is connected to the cathode of the second photodiode 2, and the connection node is node a. The anode of the second photodiode 2 is connected to a -5V voltage; the input end of the transimpedance amplifier circuit 3 is connected to node a, the output end of the transimpedance amplifier circuit 3 is connected to the input end of the frequency-selective inductor 4, and the connection node is node b, and the output end of the frequency-selective inductor 4 is connected to the input end of the frequency-selective capacitor 5; the output end of the frequency-selective capacitor 5 is connected to the reverse input end of the secondary voltage amplifier circuit 6, and the output end of the secondary voltage amplifier circuit 6 is connected to a BNC head to output an AC signal; the input end of the filter resistor 7 is connected to node b, the output end of the filter resistor 7 is connected to one end of the filter capacitor 8, and the connection node is node c, and the other end of the filter capacitor 8 is grounded; the input end of the DC in-phase proportional amplifier circuit 9 is connected to node c, and the output end of the DC in-phase proportional amplifier circuit 9 is connected to another BNC head to output a DC signal.

[0037] Furthermore, the first photodiode 1 and the second photodiode 2 use S5971 when measuring under continuous light, and use FD100 when measuring under pulsed light.

[0038] Furthermore, the filter circuit composed of the filter resistor 7 and the filter capacitor 8 can filter out AC signals.

[0039] Furthermore, the frequency-selective inductor 4 and the frequency-selective capacitor 5 form a frequency-selective circuit, which selects only the current signal at the resonant frequency to pass through, filters out noise that may be generated by other frequencies, and ensures the stability of the resonant frequency.

[0040] like Figure 2 As shown, the transimpedance amplifier circuit 3 includes a transimpedance amplifier chip OPA690, pin 4 of the transimpedance amplifier chip OPA690 is connected to node a, pin 3 of the transimpedance amplifier chip OPA690 is grounded, pin 1 of the transimpedance amplifier chip OPA690 is connected to node b, and pins 2 and 6 of the transimpedance amplifier chip OPA690 are connected to filtered -5V and +5V power supplies, respectively. A feedback capacitor C1, a feedback resistor R2, and a resonant inductor L1 are connected in parallel between pin 1 and pin 4 of the transimpedance amplifier chip OPA690.

[0041] The secondary voltage amplifier circuit 6 includes a voltage amplifier chip LMH6624, pin 3 of the voltage amplifier chip LMH6624 is connected to the frequency selection capacitor 5, a resistor R6 with a resistance value of 715Ω is connected between pin 2 and pin 6 of the voltage amplifier chip LMH6624, and pin 6 of the voltage amplifier chip LMH6624 is also connected to a resistor R8 output with a resistance value of 50Ω, and pin 4 and pin 7 of the voltage amplifier chip LMH6624 are respectively connected to the filtered -5V and +5V power supplies.

[0042] The DC in-phase proportional amplifier circuit 9 includes an amplifier chip OP27, pin 3 of the amplifier chip OP27 is connected to the filter resistor 7, a sliding variable resistor with a maximum resistance value of 10kΩ is connected between pin 2 and pin 3 of the amplifier chip OP27, pin 6 of the amplifier chip OP27 is connected to a resistor R12 with a resistance value of 50Ω, and pin 4 and pin 7 of the amplifier chip OP27 are respectively connected to filtered -5V and +5V power supplies.

[0043] like Figure 3 As shown, when the light field is incident on the first photodiode 1 and the second photodiode 2 respectively, the photodiode converts the incident light signal into a corresponding current signal. After the current signal passes through the transimpedance amplifier circuit 3 and the resonance circuit (the inductor L1 and the capacitor C1 form a resonance circuit, the capacitor C1, the resistor R2 and the amplifier chip OPA690 form a transimpedance amplifier circuit, and the resonance circuit and the transimpedance amplifier circuit 3 are combined together), it passes through the frequency selection circuit and the filter resistor 7 to divide the current signal into two parts, an AC signal and a DC signal. Among them, the AC signal passes through the frequency selection circuit and then passes through the secondary voltage amplifier circuit 6 to output from the AC end; the DC signal passes through the filter circuit composed of the filter resistor 7 and the filter capacitor 8 to further filter out the AC signal to obtain a stable DC signal. The obtained stable DC signal is then amplified by the DC in-phase proportional amplifier circuit 9 and output from the DC end. The output power spectrum of the resonant balanced zero-beat detection weak light device of the present invention under different incident light powers is shown as follows Figure 4 As shown in the figure, the output power spectrum of the detector under different optical powers. The bottom line is the electronic noise, and the rest from bottom to top are the output powers at different frequencies corresponding to optical powers of 0.5mW, 1mW, 2mW, 4mW, 8mW, 16mW, 32mW, and 64mW.

[0044] The output power spectra of the resonant balanced zero-beat detection device for weak light are shown in Figure 2. Figure 5 As shown, the measurement steps are as follows: the first step is to block any photodiode, adjust the total incident light power to 32mW, that is, the single-sided power is 16mW, and use a spectrum analyzer to record the detector's AC output spectrum at this time. This spectrum is the quantum noise spectrum detected by the photodiode that is not blocked at this time; the second step is to block another photodiode in turn, and use a spectrum analyzer to record the detector's AC output spectrum at this time; the third step is to not block the photodiode, and use a spectrum analyzer to record the AC noise spectrum of the photocurrent difference at this time. We know that although the photocurrent is subtracted, the energy of the quantum noise it carries is added. Therefore, the single-tube photocurrent noise spectrum should be half the energy of the photocurrent difference noise spectrum, and the corresponding curve in the figure is about 3dB lower than the double-sided one.

[0045] Figure 6The linearity of the detector is shown. The more the experimental data points are concentrated on a straight line, the better the linearity of the detector is, and the higher the measurement accuracy is. The dotted line in the figure represents electronic noise, the square represents the output power of the detector at different optical powers at 20MHz when the influence of electronic noise is not eliminated, and the circle represents the output power of the detector at different optical powers at 20MHz after eliminating electronic noise.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A device for detecting weak light by resonant balanced zero-beat, characterized in that: It comprises a first photodiode (1), a second photodiode (2), a transimpedance amplifier circuit (3), a frequency-selective inductor (4), a frequency-selective capacitor (5), a secondary voltage amplifier circuit (6), a filter resistor (7), a filter capacitor (8) and a direct current in-phase proportional amplifier circuit (9); The cathode of the first photodiode (1) is connected to a voltage of +5V, the anode of the first photodiode (1) is connected to the cathode of the second photodiode (2), the connection node is node a, and the anode of the second photodiode (2) is connected to a voltage of -5V; The input end of the transimpedance amplifier circuit (3) is connected to the node a, the output end of the transimpedance amplifier circuit (3) is connected to the input end of the frequency-selective inductor (4), the connection node is the node b, and the output end of the frequency-selective inductor (4) is connected to the input end of the frequency-selective capacitor (5); The output end of the frequency selection capacitor (5) is connected to the reverse input end of the secondary voltage amplifier circuit (6), and the output end of the secondary voltage amplifier circuit (6) is connected to the BNC head; The input end of the filter resistor (7) is connected to the node b, the output end of the filter resistor (7) is connected to one end of the filter capacitor (8), the connection node is the node c, and the other end of the filter capacitor (8) is grounded; The input end of the direct current in-phase proportional amplifier circuit (9) is connected to the node c, and the output end of the direct current in-phase proportional amplifier circuit (9) is connected to another BNC head.

2. The device for detecting weak light by resonant balanced zero-beat detection according to claim 1, characterized in that: The first photodiode (1) and the second photodiode (2) use S5971 when measuring under continuous light, and use FD100 when measuring under pulsed light.

3. The device for detecting weak light by resonant balanced zero-beat according to claim 1, characterized in that: The transimpedance amplifier circuit (3) comprises a transimpedance amplifier chip OPA690; Pin 4 of the transimpedance amplifier chip OPA690 is connected to the node a, pin 3 of the transimpedance amplifier chip OPA690 is grounded, pin 1 of the transimpedance amplifier chip OPA690 is connected to the node b, and pin 2 and pin 6 of the transimpedance amplifier chip OPA690 are respectively connected to the filtered -5V and +5V power supplies.

4. The device for detecting weak light by resonant balanced zero-beat according to claim 1, characterized in that: The secondary voltage amplifier circuit (6) comprises a voltage amplifier chip LMH6624; Pin 3 of the voltage amplifier chip LMH6624 is connected to the frequency selection capacitor (5), a resistor (R6) is connected between pin 2 and pin 6 of the voltage amplifier chip LMH6624, and pin 6 of the voltage amplifier chip LMH6624 is also connected to a resistor (R8) output, and pin 4 and pin 7 of the voltage amplifier chip LMH6624 are respectively connected to filtered -5V and +5V power supplies.

5. The device for detecting weak light by resonant balanced zero-beat according to claim 1, characterized in that: The DC in-phase proportional amplifier circuit (9) comprises an amplifier chip OP27; Pin 3 of the amplifier chip OP27 is connected to the filter resistor (7), a sliding resistor is connected between pin 2 and pin 3 of the amplifier chip OP27, pin 6 of the amplifier chip OP27 is connected to the resistor (R12), and pin 4 and pin 7 of the amplifier chip OP27 are respectively connected to filtered -5V and +5V power supplies.

6. The device for detecting weak light by resonant balanced zero-beat according to claim 1, characterized in that: The frequency-selective inductor (4) and the frequency-selective capacitor (5) form a frequency-selective circuit, and the frequency-selective circuit is used to filter out noise by passing the signal at the resonant frequency.

7. The device for detecting weak light by resonant balance zero beat according to claim 3, characterized in that: A feedback capacitor (C1), a feedback resistor (R2) and a resonant inductor (L1) are connected in parallel between pin 1 and pin 4 of the transimpedance amplifier chip OPA690.

8. The device for detecting weak light by resonant balanced zero-beat according to claim 5, characterized in that: The maximum resistance of the sliding rheostat is 10 kΩ.

Images