Whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope driven by a broadband light source

Abstract

The present invention discloses a wide-spectrum light source-driven whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope, which belongs to the field of gyroscope optical path system design. The entire system consists of two parts: an optical system and a signal detection system. The optical system includes a wide-spectrum light source, a push-pull Y-waveguide, a circulator, a transmission-type multi-mode transmission whispering gallery optical microcavity and a photodetector; the signal detection system includes a modulation and demodulation module and a low-pass filter module. In the present invention, the whispering gallery optical microcavity is connected to the wide-spectrum light source using a symmetrical connection method, and the multi-mode transmission characteristics of the whispering gallery optical microcavity and the multi-mode co-detection mechanism are utilized to greatly improve the detection light power, solve the problem of the increase in the quality factor of the single-mode resonant cavity causing the detection light power to decrease, and improve the detection accuracy of the system.

Description

Technical Field

[0001] The present invention belongs to the field of gyroscope optical path system design, and in particular relates to a whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope driven by a wide-spectrum light source. Background Art

[0002] Resonant optical gyros (ROGs) based on the Sagnac effect utilize a high-quality resonant cavity to enhance the Sagnac effect, achieving high precision in a compact size and offering unique advantages in miniaturization. However, traditional RGOs use narrow-linewidth lasers as their driving light source, severely limiting their accuracy due to noise associated with the coherence of the light source. Recently proposed RGOs driven by broadband light sources utilize low-coherence, broadband light sources, significantly reducing the impact of this noise at the source. However, when driven by broadband light sources, the high-quality resonant cavity acts as a filter. The higher the quality factor, the weaker the light power transmitted through the cavity. This significantly reduces the actual detection power of a RGO using a high-quality resonant cavity as the angular velocity sensing element, directly impacting the signal-to-noise ratio (SNR) of the gyro's detection system. This places extremely stringent demands on the detection system's performance for high-precision gyros. A high-quality resonant cavity is a prerequisite for achieving high sensitivity in RGOs. Therefore, using broadband light sources as driving light sources urgently requires resolving the trade-off between gyro sensitivity and the SNR of the detection system. Summary of the Invention

[0003] The present invention proposes a wide-spectrum light source-driven whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope.

[0004] The technical solution adopted in the present invention is as follows:

[0005] In the first aspect, the present invention discloses a broadband light source-driven whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope, comprising an optical system and a signal detection system. The optical system includes a broadband light source, a push-pull Y-waveguide, a circulator, a transmissive multi-mode transmission whispering gallery optical microcavity, and a photodetector. The signal detection system consists of a modulation and demodulation module and a low-pass filtering module.

[0006] A broadband light source, a circulator, and a push-pull Y-waveguide are connected in sequence. The two output ports of the push-pull Y-waveguide are connected to a pair of transmission ports of the whispering gallery optical microcavity. The circulator is also connected to a photodetector.

[0007] The photodetector is connected to the modulation and demodulation module. The modulation and demodulation module generates a modulation signal and outputs it to the push-pull Y-waveguide. The modulation and demodulation module demodulates the output of the photodetector and outputs the demodulated signal to the push-pull Y-waveguide and low-pass filter module. The demodulated signal passes through the low-pass filter module and is output to an external data recorder as the gyroscope output of the gyroscope.

[0008] In a second aspect, the present invention discloses a method for detecting a whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope of the gyroscope, comprising the following steps:

[0009] The broadband light source outputs broadband light to the first port of the circulator, and the broadband light is then output to the push-pull Y-waveguide through the second port of the circulator. The push-pull Y-waveguide splits the broadband light into two light paths and couples them into the interior of the whispering gallery optical microcavity through a pair of transmission ports. Both light paths are transmitted in multiple optical modes in the whispering gallery optical microcavity. The two light paths transmitted through each optical mode are then coupled to corresponding transmission ports in the whispering gallery optical microcavity. The two light paths after multi-mode transmission are output to the push-pull Y-waveguide through corresponding transmission ports. The push-pull Y-waveguide combines the two received light paths into one light beam, and outputs the combined light beam to the photodetector through the circulator for photoelectric conversion. The photodetector outputs an electrical signal to the modulation and demodulation module.

[0010] The modulation and demodulation module demodulates the electrical signal output by the photodetector to obtain a demodulated signal, and outputs the demodulated signal to the low-pass filtering module; the modulation and demodulation module generates a modulation signal and outputs it to the push-pull Y-waveguide, which phase-modulates the light passing through it according to the modulation signal; the low-pass filtering module performs low-pass filtering on the demodulated signal, and the filtered demodulated signal is output to an external data recorder as the gyroscope output of the gyroscope.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The present invention uses a transmissive whispering gallery optical microcavity that supports multimode transmission to greatly improve the power utilization of the broadband light source, increase the detection light power at the transmission end of the microcavity, and ultimately improve the signal-to-noise ratio of the detection system of the resonant optical gyroscope, which is beneficial to improving the actual detection accuracy of the gyroscope.

[0013] The present invention uses a whispering gallery optical microcavity with transmissive multimode transmission to solve the problem that a single-mode resonant cavity cannot be used due to too low transmittance, thereby improving the signal-to-noise ratio of the detection system.

[0014] The present invention utilizes a wide-spectrum light source to effectively reduce optical parasitic effects in the system, thereby greatly improving the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1This is a schematic diagram of the structure of a whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope driven by a wide-spectrum light source;

[0016] Figure 2 This is a schematic diagram of a specific implementation case of a whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope driven by a wide-spectrum light source;

[0017] Figure 3 is the transmission spectrum of the whispering gallery optical microcavity supporting multimode transmission;

[0018] Figure 4 is the transmission spectrum of an ordinary single-mode resonant cavity.

[0019] In the figure: 1. Broad-spectrum light source; 2. Circulator; 3. Push-pull Y-waveguide; 4. Photodetector; 5. Whispering gallery optical microcavity; 6. Modem module; 7. Low-pass filter module; 8. Data recorder. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0022] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0023] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; it can mean mechanical connection, electrical connection, physical connection, or wireless communication connection; it can mean direct connection or indirect connection through an intermediate medium; it can mean internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

[0025] The purpose of the present invention is to provide a resonant optical gyroscope with multi-mode co-detection using a whispering gallery optical microcavity driven by a wide-spectrum light source. The device uses a whispering gallery optical microcavity with a high quality factor and multi-mode transmission support as the angular velocity sensing unit. The high quality factor of the microcavity ensures the high sensitivity of the resonant optical gyroscope, while the multi-mode transmission support characteristic facilitates increased optical power output at the transmission end of the microcavity.

[0026] Whispering gallery optical microcavities can be divided into two basic structural types based on the fiber coupling method: a reflective structure based on single-sided fiber coupling and a transmissive structure based on double-sided fiber coupling. In this field, the reflective structure based on single-sided fiber coupling is commonly used. This is mainly because, compared to transmissive whispering gallery optical microcavities, reflective whispering gallery optical microcavities have only one coupling region, thus achieving a higher Q (quality factor) value and higher response sensitivity. Reflective whispering gallery optical microcavities have a wide range of applications in theoretical physics and nonlinear optics. For example, they can utilize the strong interaction between light and matter within the microcavity to generate single-photon and entangled light sources, or perform quantum optical frequency conversion. The optical frequency combs generated by the nonlinear effects within the microcavity play an important role in time measurement and fiber-optic communications. Transmissive whispering gallery mode microcavities can also be used to generate optical frequency combs and are also used in biological and chemical sensing and as high-precision optical filters in optical communications. Whispering gallery optical microcavities, whether reflective or transmissive, typically rely on one or more specific eigenmodes within the cavity to achieve their basic functions in these applications. However, the present invention utilizes all excited modes within the whispering gallery optical microcavity while also leveraging the microcavity's transmissive structure to improve the system's overall signal-to-noise ratio.

[0027] like Figure 1As shown, the present invention provides a wide-spectrum light source-driven whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope, which includes an optical system consisting of a wide-spectrum light source, a push-pull Y-waveguide, a circulator, a transmissive multi-mode transmission whispering gallery optical microcavity (transmissive whispering gallery optical microcavity) and a photodetector, as well as a signal detection system consisting of a modulation and demodulation module and a low-pass filtering module.

[0028] The output of the broadband light source is connected to the first port of the circulator; the second port of the circulator is connected to the input port of the push-pull Y-branch; the two output ports of the push-pull Y-waveguide are connected to a pair of transmission ports of a whispering gallery optical microcavity for transmissive multimode transmission, while the other pair of transmission ports of the whispering gallery optical microcavity remains unused; the third port of the circulator is connected to a photodetector. The output signal of the photodetector enters the signal detection system, is processed by the modem module and the low-pass filter module, and is finally input to an external data recorder. The modem module is also connected to the push-pull Y-waveguide.

[0029] The higher the quality factor, the lower the light transmittance of a single-mode transmissive resonant cavity. Too low a light transmittance makes it impractical. Transmissive whispering gallery optical microcavities often allow multiple modes to propagate, and each propagation mode is equivalent to a single-mode resonant cavity with a high quality factor. The final optical power received by the photoelectric detection point is the sum of the optical powers transmitted by each mode, such as Figure 3 and Figure 4 As shown in Figure 2, the transmission power of the whispering gallery optical microcavity is much greater than that of the single-mode resonant cavity. Therefore, the use of the whispering gallery optical microcavity enables the application of high-quality factor microcavities in resonant optical gyroscopes driven by broadband light sources, greatly improving the detection light power. In addition, the whispering gallery optical microcavity can achieve up to 10 8 The above quality factors further improve the detection sensitivity of the resonant optical gyroscope.

[0030] In the present invention, the structure of the transmissive multimode transmission whispering gallery optical microcavity is a double-side coupled microcavity, and the processing method of the whispering gallery optical microcavity is micro-nano processing, and the specific processes include dry etching and wet etching.

[0031] The high-quality factor whispering gallery optical microcavity in this scheme is a transmissive structure, and adopts a transmissive symmetrical connection method in which clockwise and counterclockwise optical signals share the same input and output ports, which is extremely beneficial to improving the signal-to-noise ratio of the gyroscope output.

[0032] like Figure 2 As shown, it is a schematic diagram of a specific implementation case of a whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope driven by a wide-spectrum light source.

[0033] The present invention also discloses a method for detecting a whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope of the gyroscope, comprising the following steps:

[0034] The broadband light source 1 outputs broadband light to the first port of the circulator, and the broadband light is then output to the push-pull Y-waveguide 3 through the second port of the circulator 2. The push-pull Y-waveguide 3 splits the broadband light into two paths of light and couples them into the interior of the whispering gallery optical microcavity 5 through a pair of transmission ports. Both paths of light are transmitted in the whispering gallery optical microcavity 5 in multiple optical modes. Then, the two paths of light transmitted through each optical mode are respectively coupled to the corresponding transmission ports in the whispering gallery optical microcavity 5. The two paths of light after multi-mode transmission are respectively output to the push-pull Y-waveguide 3 through the corresponding transmission ports. The push-pull Y-waveguide 3 combines the two received paths of light into one beam of light, and outputs the combined beam of light to the photodetector 4 through the circulator 2. The photodetector 4 performs photoelectric conversion on the received light and outputs an electrical signal to the modulation and demodulation module 6.

[0035] The modulation and demodulation module 6 generates a modulation signal and outputs it to the push-pull Y-waveguide 3. The push-pull Y-waveguide 3 performs phase modulation on the light passing through it according to the modulation signal. The modulation and demodulation module 6 demodulates the electrical signal output by the photodetector 4 to obtain a demodulated signal, and outputs the demodulated signal to the low-pass filter module 7. The low-pass filter module 7 performs low-pass filtering on the demodulated signal. The filtered demodulated signal is output to an external data recorder as the gyroscope output of the gyroscope.

[0036] In a specific embodiment, the present invention uses a mode number of 67 and a Q value of 2×10 8 The broad-spectrum light source emits 20mW of broad-spectrum light in the whispering gallery optical microcavity of the present invention. After a series of transmissions of the broad-spectrum light in the whispering gallery optical microcavity, the power of the light received by the photodetector is around 10μW, and the data recorder measures the gyroscope's random walk at 0.8° / h. 1 / 2 ; Then, a single-mode resonant cavity with the same Q value is used to replace the whispering gallery optical microcavity of the transmissive multimode transmission of the present invention. The broadband light source also emits broadband light of the same power. After a series of transmissions of the broadband light in the single-mode cavity, the test shows that the light received by the photodetector is less than 0.15μW. Because the light power at this time is too small, the gyroscope signal is submerged in the noise and cannot be detected. Therefore, the present invention uses the whispering gallery optical microcavity of transmissive multimode transmission to greatly improve the power utilization rate of the broadband light source, increase the detection light power at the transmission end of the microcavity, and ultimately improve the signal-to-noise ratio of the detection system of the resonant optical gyroscope, which is beneficial to improving the actual detection accuracy of the gyroscope. It also solves the problem that the single-mode resonant cavity cannot be used due to too low transmittance, thereby improving the signal-to-noise ratio of the detection system.

[0037] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they are not to be construed as limiting the scope of the present invention. Persons skilled in the art will readily appreciate that variations and modifications may be made without departing from the spirit of the present invention, and all such variations and modifications fall within the scope of protection of the present invention.

Claims

1. A detection method for a whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope driven by a wide-spectrum light source, characterized in that: The system comprises an optical system and a signal detection system. The optical system includes a broadband light source, a push-pull Y-waveguide, a circulator, a transmissive multimode whispering gallery optical microcavity, and a photodetector. The signal detection system comprises a modulation and demodulation module and a low-pass filter module. The broadband light source, the circulator, and the push-pull Y-waveguide are sequentially connected. The two output ports of the push-pull Y-waveguide are connected to a pair of transmissive ports of the whispering gallery optical microcavity. The circulator is also connected to the photodetector. The photodetector is connected to a modulation and demodulation module. The modulation and demodulation module generates a modulation signal and outputs it to the push-pull Y-waveguide. The modulation and demodulation module demodulates the output of the photodetector and outputs the demodulated signal to the low-pass filter module. The demodulated signal passes through the low-pass filter module and is output to an external data recorder as the gyro output of the gyroscope. The whispering gallery optical microcavity adopts a transmissive symmetrical connection method in which the input and output ports of the clockwise and counterclockwise optical signals are shared; The detection method comprises the following steps: The broadband light source outputs broadband light to the first port of the circulator, and the broadband light is then output to the push-pull Y-waveguide through the second port of the circulator. The push-pull Y-waveguide splits the broadband light into two light paths and couples them into the interior of the whispering gallery optical microcavity through a pair of transmission ports. Both light paths are transmitted in multiple optical modes in the whispering gallery optical microcavity. The two light paths transmitted through each optical mode are then coupled to corresponding transmission ports in the whispering gallery optical microcavity. The two light paths after multi-mode transmission are output to the push-pull Y-waveguide through corresponding transmission ports. The push-pull Y-waveguide combines the two received light paths into one light beam, and outputs the combined light beam to the photodetector through the circulator for photoelectric conversion. The photodetector outputs an electrical signal to the modulation and demodulation module. The modulation and demodulation module demodulates the electrical signal output by the photodetector to obtain a demodulated signal, and outputs the demodulated signal to the low-pass filtering module; the modulation and demodulation module generates a modulation signal and outputs it to the push-pull Y-waveguide, which phase-modulates the light passing through it according to the modulation signal; the low-pass filtering module performs low-pass filtering on the demodulated signal, and the filtered demodulated signal is output to an external data recorder as the gyroscope output of the gyroscope.

2. The detection method of the whispering gallery optical microcavity multi-mode co-detection resonant optical gyroscope based on a broadband light source drive according to claim 1, characterized in that: The broadband light source is connected to the first port of the circulator, the second port of the circulator is connected to the input end of the push-pull Y-waveguide, and the third port of the circulator is connected to the input end of the photodetector.

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