Temperature detecting device, method and laser ultra-low temperature monitoring system

Abstract

The application discloses a temperature detection device, a temperature detection method and a laser ultra-low temperature monitoring system. The temperature detection device comprises a silicon waveguide, the silicon waveguide comprises a transmission waveguide and a coupling waveguide, the coupling waveguide, the input port and the output port of the transmission waveguide are arranged on a substrate, the transmission waveguide is at least partially in a free vibration suspended state, the suspended section of the transmission waveguide has a horizontal spacing with the coupling waveguide, at a non-absolute zero temperature, the thermal motion of molecules of the suspended section of the transmission waveguide causes the thermal mechanical vibration of the suspended section of the transmission waveguide, the spacing between the suspended section of the transmission waveguide and the coupling waveguide changes in real time and dynamically, the light coupling energy exchange between the suspended section of the transmission waveguide and the coupling waveguide changes in real time, and the light signal output by the waveguide output port also changes in real time and dynamically. The application realizes the laser ultra-low temperature monitoring based on the molecular thermal motion by using the transmission characteristics of the optical waveguide, and reduces the measurement technical difficulty based on the molecular thermal motion temperature measurement principle.

Description

Technical Field

[0001] This invention relates to the field of temperature measurement, and more specifically to a temperature detection device, method, and laser cryogenic monitoring system. Background Technology

[0002] With advancements in technology, aerospace, superconductivity, and quantum technology have all placed demands on cryogenic monitoring. The monitored temperatures vary widely depending on the medium used, ranging from liquid nitrogen (77K), liquid helium (4K), to cold atom systems. While there are numerous principles underlying temperature sensors, their performance, linearity, and other key characteristics change significantly in the cryogenic region, making them difficult to apply. Furthermore, some measuring devices inherently possess measurement uncertainties in the cryogenic region, making it difficult to achieve the required accuracy; these include those based on platinum, germanium, and carbon-based resistors.

[0003] There are two main categories of laser-based temperature measurement methods: one based on the relationship between refractive index and temperature, and the other based on the relationship between Raman scattering, Brillouin scattering, Rayleigh scattering, and temperature. More precise cryogenic measurement techniques often employ methods that directly measure the thermal energy of molecules, i.e., temperature. These methods include: measuring molecular energy based on the trajectories of molecules in precise gradient magnetic fields, and deriving the target energy from the relationship between laser-driven molecules and the molecular trajectory. While these methods are easy to implement, they are often unsuitable for cryogenic measurements because the measurement error itself is at the level of the target value. Methods that can be effectively used are complex and difficult to construct, requiring correction and compensation for higher-order effects in principle.

[0004] The thermal motion of molecules is a direct manifestation of temperature, and as mentioned above, directly measuring the motion of molecules is extremely difficult. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a temperature detection device, method and laser cryogenic monitoring system, which utilizes the transmission characteristics of optical waveguides to realize laser cryogenic monitoring based on molecular thermal motion, thereby reducing the technical difficulty of measurement based on the principle of molecular thermal motion temperature measurement.

[0006] The technical solution of the present invention is implemented as follows: The present invention discloses a temperature detection device, including a silicon waveguide, characterized in that: the silicon waveguide includes a transmission waveguide and a coupling waveguide, one end of the transmission waveguide is connected to a waveguide input port, the other end of the transmission waveguide is connected to a waveguide output port, the waveguide input port, the waveguide output port and the coupling waveguide are respectively disposed on a substrate, the transmission waveguide is at least partially in a suspended state that can vibrate freely, the ratio of the length of the suspended section of the transmission waveguide to the cross-sectional dimension of the transmission waveguide core layer is greater than 1000, there is a horizontal distance between the suspended section of the transmission waveguide and the coupling waveguide, and there is light energy exchange between the two due to the optical coupling effect;

[0007] At temperatures not at absolute zero, the molecular thermal motion of the suspended segment of the transmission waveguide causes thermomechanical vibration in the suspended segment, resulting in a real-time dynamic change in the distance between the suspended segment and the coupled waveguide. This leads to a real-time change in the optical coupling energy exchange between the suspended segment and the coupled waveguide, and consequently, a real-time dynamic change in the optical signal output from the waveguide output port.

[0008] Furthermore, when the cross-section of the transmission waveguide core layer is rectangular, the ratio of the length of the suspended section of the transmission waveguide to the length of the long side of the cross-section of the transmission waveguide core layer is greater than 1000.

[0009] The cross-sectional dimensions of the suspended section of the transmission waveguide are in the nanometer range, and the length of the suspended section is in the micrometer range.

[0010] Furthermore, the suspended segments of the coupled waveguide and the transmission waveguide are parallel to each other on the same horizontal plane, and the horizontal distance between the suspended segments of the coupled waveguide and the transmission waveguide is greater than 10 nanometers and less than 100 nanometers.

[0011] Furthermore, a groove is provided on the substrate directly below the suspended section of the transmission waveguide, so that the suspended section of the transmission waveguide is in a suspended state.

[0012] Furthermore, the temperature detection device of the present invention also includes an input optical fiber and an output optical fiber. One end of the input optical fiber is connected to a waveguide input port, and the other end of the input optical fiber is connected to an optical fiber input interface. One end of the output optical fiber is connected to a waveguide output port, and the other end of the output optical fiber is connected to an optical fiber output interface.

[0013] Furthermore, the transmission waveguide includes a first transmission waveguide segment, a second transmission waveguide segment, and a third transmission waveguide segment. One end of the first transmission waveguide segment is connected to the waveguide input port, the other end of the first transmission waveguide segment is connected to one end of the second transmission waveguide segment, the other end of the second transmission waveguide segment is connected to one end of the third transmission waveguide segment, and the other end of the third transmission waveguide segment is connected to the waveguide output port. The first and third transmission waveguide segments are disposed on the substrate, and the second transmission waveguide segment is a suspended segment of the transmission waveguide, which is in a suspended state.

[0014] Furthermore, the coupled waveguide includes at least one coupled sub-waveguide, each coupled sub-waveguide being located beside the suspended section of the transmission waveguide. When there are multiple coupled sub-waveguides, the multiple coupled sub-waveguides are sequentially spaced along the transmission direction of light in the suspended section of the transmission waveguide, so that the laser in the suspended section of the transmission waveguide sequentially exchanges optical energy with each coupled sub-waveguide due to optical coupling effect.

[0015] Furthermore, the spacing between two adjacent coupled subwaveguides is greater than twice the operating wavelength.

[0016] Furthermore, when the absolute zero is zero, the coupling length of the optical coupling between the coupled sub-waveguide and the suspended section of the transmission waveguide is Lc, then the length of the coupled sub-waveguide is set to twice Lc.

[0017] Furthermore, the coupler sub-waveguide is a straight strip waveguide, which has a guided mode at the operating wavelength; at least the suspended section of the transmission waveguide is a strip waveguide, which also has a guided mode at the operating wavelength.

[0018] Furthermore, the suspended sections of each coupled sub-waveguide and the transmission waveguide are arranged in parallel and spaced apart.

[0019] Furthermore, the suspended segments of each coupled sub-waveguide and the transmission waveguide are located on the same horizontal plane.

[0020] This invention discloses a laser cryogenic monitoring system, comprising a laser source, a photoelectric conversion module, a signal acquisition card, a computer system, and a temperature detection device as described above. The laser source emits laser light; the temperature detection device receives the laser light emitted by the laser source and outputs the real-time changing optical signal to the photoelectric conversion module; the photoelectric conversion module converts the input optical signal into an electrical signal and outputs the electrical signal to the signal acquisition card; the signal acquisition card acquires the electrical signal and outputs the signal data to the computer system; the computer system calculates the standard deviation of the signal data and calculates the required monitoring temperature based on the correspondence between the standard deviation of the signal data and the temperature.

[0021] This invention discloses a temperature detection method, implemented using the temperature detection device described above, comprising the following steps:

[0022] The waveguide input port receives light and outputs it to the transmission waveguide. The light propagates in the transmission waveguide and is coupled into the coupling waveguide from the suspended section of the transmission waveguide, and then coupled back into the suspended section of the transmission waveguide from the coupling waveguide. The molecular thermal motion in the suspended section of the transmission waveguide causes thermomechanical vibration in the suspended section of the transmission waveguide. The thermomechanical vibration of the suspended section of the transmission waveguide causes the distance between the suspended section of the transmission waveguide and the coupling waveguide to change dynamically in real time. The dynamic change in the distance between the suspended section of the transmission waveguide and the coupling waveguide causes the optical coupling energy exchange between the suspended section of the transmission waveguide and the coupling waveguide to change dynamically in real time, which in turn causes the optical signal output from the waveguide output port to change dynamically in real time.

[0023] The required temperature is monitored by monitoring changes in the optical signal output from the waveguide output port.

[0024] The present invention has at least the following beneficial effects:

[0025] (1) The temperature measurement technology based on the direct molecular thermal motion temperature measurement principle is technically difficult to implement. This invention adopts a micro-nano scale structure, which can convert molecular thermal motion into thermomechanical vibration of the structure, and then transmit optical signals in the micro-nano structure. By monitoring the influence of the thermomechanical vibration of the micro-nano structure on the optical signal transmission characteristics, the monitoring of molecular thermal motion, i.e. temperature, can be realized. The technical implementation difficulty and cost are relatively low.

[0026] (2) The micro / nano structure used in this invention is a straight waveguide with both ends fixed and the middle suspended. The cross-sectional scale of the waveguide is on the nanometer scale, and the length of the waveguide is on the micrometer scale. The extremely small vibration volume and correspondingly extremely small mass can effectively convert molecular thermal motion into thermomechanical vibration of the waveguide structure. On the other hand, the amplitude of thermomechanical vibration is directly proportional to the waveguide length and inversely proportional to the waveguide cross-sectional scale. By designing the length of the waveguide to be much larger than the cross-sectional scale of the waveguide, a larger amplitude of thermomechanical vibration can be obtained at the same temperature, thereby improving the subsequent detection sensitivity.

[0027] (3) This invention utilizes the coupling characteristics of optical waveguides to monitor the thermomechanical vibration of the transmission waveguide. To enhance the sensitivity of thermomechanical vibration detection, the coupling waveguide is designed as a set of N sub-waveguides arranged in a linear pattern. The optical signal in the transmission waveguide will be coupled to each sub-waveguide sequentially. Thermomechanical vibration causes changes in the coupling characteristics of each sub-waveguide, and the final output optical signal will be N times the change caused by a single sub-waveguide, which will improve the detection sensitivity.

[0028] (4) The computer analysis in this invention is the standard deviation of the signal, rather than the strength of the signal itself. The higher the system temperature, the more significant the thermomechanical vibration, the greater the dynamic change of the spacing between the suspended sections of the coupling waveguide and the transmission waveguide, and the more significant the dynamic change of the coupled output optical signal, and the greater the standard deviation. Monitoring the standard deviation of the signal, rather than the strength of the signal itself, has higher monitoring robustness. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the laser cryogenic monitoring system of the present invention;

[0031] Figure 2 This is a schematic diagram of the temperature detection device of the present invention;

[0032] Figure 3This is a schematic diagram of a silicon waveguide according to an embodiment of the present invention;

[0033] Figure 4 This is a partially enlarged schematic diagram of a silicon waveguide according to an embodiment of the present invention;

[0034] Figure 5 This diagram illustrates the relationship between the spacing between the suspended segments of the coupled waveguide and the transmission waveguide and the difference in the supermode propagation constant.

[0035] Figure 6 This is a schematic diagram illustrating the relationship between the refractive index of silicon and temperature.

[0036] Figure 7 This is a schematic diagram showing the relationship between the maximum amplitude of thermomechanical vibration occurring in the suspended section of a transmission waveguide according to an embodiment of the present invention and temperature.

[0037] Figure 8 This is a schematic diagram illustrating the effect of spacing on the relative output power in one embodiment of the present invention;

[0038] Figure 9 This is a schematic diagram illustrating the relationship between the relative output power fluctuation amplitude and temperature according to an embodiment of the present invention;

[0039] Figure 10 This is a schematic diagram illustrating the relationship between signal standard deviation and temperature in one embodiment of the present invention.

[0040] In the attached diagram, 1 is a laser source, 2 is a temperature detection device, 21 is an optical fiber input port, 22 is an input optical fiber, 23 is an output optical fiber, 24 is an optical fiber output port, 25 is a silicon waveguide, 251 is a substrate, 2511 is a groove, 252 is a waveguide input port, 2531 is a first transmission waveguide segment, 2532 is a second transmission waveguide segment, 2533 is a third transmission waveguide segment, 254 is a coupling waveguide, 2541 is a coupling sub-waveguide, 255 is a waveguide output port, 3 is a photoelectric conversion module, 4 is a signal acquisition card, and 5 is a computer system. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" or "several" means two or more.

[0044] Research has found that in micro / nanostructured materials, due to their extremely small size, the molecular thermal motion of the material itself can induce thermomechanical vibrations within the micro / nanostructure. Utilizing this thermomechanical vibration characteristic, temperature can be monitored by observing these vibrations. This method can effectively reduce the measurement difficulty based on the principle of molecular thermal motion thermometry.

[0045] The basic principle of ultra-low temperature monitoring in this invention is as follows: Atoms and molecules in all matter are in constant random motion, and their vibration amplitude is directly proportional to temperature. For a macroscopic structure, the thermal motion of atoms and molecules within the structure can hardly cause observable mechanical vibrations. However, when the scale of the structure shrinks to the micro-nano scale, the thermal motion of atoms and molecules within the structure will cause observable thermomechanical vibrations. These thermomechanical vibrations originate directly from the thermal motion of atoms and molecules within the structure; therefore, this is an effective principle for observing the thermal motion of atoms and molecules. By designing the micro-nano structure as an optical waveguide, even slight changes in the structural parameters of the optical waveguide due to thermomechanical vibrations will cause changes in the transmission characteristics of the optical waveguide. Thus, the temperature of the system can be monitored by monitoring changes in the output optical signal of the optical waveguide.

[0046] The micro / nano structure used in this invention is a straight strip-shaped structure fixed at both ends and suspended in the middle. This structure is simple and easy to fabricate. Furthermore, its transmission characteristics are easy to analyze when used for light transmission, improving the accuracy of measurement data. The cross-sectional scale of the structure is on the nanometer scale, and the length is on the micrometer scale, allowing light to form guided modes within the structure. Smaller volume corresponds to smaller mass, which facilitates the conversion of the thermal motion of atoms and molecules into thermomechanical vibrations. For a straight strip structure fixed at both ends, it possesses an inherent vibrational frequency. Studies show that this inherent vibrational frequency is inversely proportional to the square of the structure's length and directly proportional to the side length of the cross-section. The vibrational amplitude generated by the thermal motion of atoms and molecules is inversely proportional to the inherent vibrational frequency and directly proportional to the first half power of the system temperature. Therefore, designing the structure to have a length much larger than the cross-sectional scale of the waveguide allows for a larger vibrational amplitude at the same temperature, resulting in greater changes in light transmission characteristics and thus improving detection sensitivity.

[0047] Example 1

[0048] See Figures 2 to 4 This invention provides a temperature detection device, including a silicon waveguide 25. The silicon waveguide 25 includes a transmission waveguide and a coupling waveguide 254. One end of the transmission waveguide is connected to a waveguide input port 252, and the other end is connected to a waveguide output port 255. The waveguide input port 252, waveguide output port 255, and coupling waveguide 254 are respectively disposed on a substrate 251. The transmission waveguide is at least partially in a freely vibrating suspended state. There is a horizontal distance between the suspended section of the transmission waveguide and the coupling waveguide 254, and there is light energy exchange between them due to optical coupling effect. The coupling waveguide 254 and the suspended section of the transmission waveguide are parallel to each other on the same horizontal plane. The horizontal distance between the coupling waveguide 254 and the suspended section of the transmission waveguide is greater than 10 nanometers and less than 100 nanometers. The ratio of the length of the suspended section of the transmission waveguide to the cross-sectional dimension of the transmission waveguide core (when the cross-section of the transmission waveguide core is rectangular, the cross-sectional dimension of the transmission waveguide core refers to the side length of the cross-section of the transmission waveguide core) is greater than 1000.

[0049] The coupled waveguide 254, the suspended section of the transmission waveguide, and the gap between them constitute a combined waveguide. This combined waveguide has two supermodes, and the difference in the propagation constants of the two supermodes determines the coupling length Lc, which is the required transmission length for light to couple completely from the suspended section of the transmission waveguide into the coupled waveguide 254, or vice versa. The smaller the coupling length Lc, the stronger the coupling between the two waveguides. Figure 5 The changes in the propagation constant difference between the two supermodes of the combined waveguide are shown when the spacing between the suspended section of the transmission waveguide and the coupling waveguide 254 varies from 40 nm to 60 nm at temperatures of 3 K, 30 K, and 90 K. Figure 5This indicates that the spacing between the suspended section of the transmission waveguide and the 254-degree coupling waveguide significantly affects the difference in propagation constant. Figure 5 The three curves representing different temperatures are essentially overlapping. This indicates that although the refractive index of silicon changes slightly at different temperatures, such as... Figure 6 The figure shows the change in refractive index of silicon from 0K to 100K, but the effect of this refractive index change on the difference in propagation constant is much smaller than the effect of the change in waveguide spacing on the difference in propagation constant. It can be approximated that the spacing between the suspended section of the transmission waveguide and the coupling waveguide 254 determines the difference in propagation constant of the two supermodes in the combined waveguide, that is, it determines the optical coupling effect of the combined waveguide.

[0050] At temperatures not exceeding absolute zero, the molecular thermal motion of the suspended segment of the transmission waveguide causes thermomechanical vibrations in that segment. Figure 7 The relationship between the amplitude of thermomechanical vibrations in the suspended section of the transmission waveguide and the temperature T (K) is shown. It can be found that the higher the temperature, the greater the amplitude.

[0051] The thermomechanical vibration of the suspended section of the transmission waveguide causes the spacing between the suspended section and the coupling waveguide 254 to change dynamically in real time. This results in a real-time dynamic change in the difference between the propagation constants of the two supermodes in the combined waveguide. The difference in the supermode propagation constants determines the optical coupling energy exchange between the suspended section of the transmission waveguide and the coupling waveguide 254. This inevitably leads to real-time changes in the optical coupling between the suspended section of the transmission waveguide and the coupling waveguide 254, and ultimately, a real-time dynamic change in the optical signal output from the output port of the silicon waveguide 25.

[0052] In some embodiments, substrate 251 is a silicon dioxide substrate.

[0053] Furthermore, a groove 2511 is provided on the substrate 251 directly below the suspended section of the transmission waveguide, so that the suspended section of the transmission waveguide is in a suspended state.

[0054] In some embodiments, the width of the groove 2511 is greater than the sum of the width of the suspended section of the transmission waveguide and the operating wavelength.

[0055] In some embodiments, the distance between the suspended section of the transmission waveguide and the bottom of the groove 2511 is greater than 200 nm.

[0056] Furthermore, the temperature detection device 2 also includes an input optical fiber 22 and an output optical fiber 23. One end of the input optical fiber 22 is connected to the waveguide input port 252, and the other end of the input optical fiber 22 is connected to the optical fiber input interface 21. One end of the output optical fiber 23 is connected to the waveguide output port 255, and the other end of the output optical fiber 23 is connected to the optical fiber output interface 24.

[0057] In some embodiments, the transmission waveguide is divided into three segments, including a first transmission waveguide segment 2531, a second transmission waveguide segment 2532, and a third transmission waveguide segment 2533. One end of the first transmission waveguide segment 2531 is connected to the waveguide input port 252, the other end of the first transmission waveguide segment 2531 is connected to one end of the second transmission waveguide segment 2532, the other end of the second transmission waveguide segment 2532 is connected to one end of the third transmission waveguide segment 2533, and the other end of the third transmission waveguide segment 2533 is connected to the waveguide output port 255. The first transmission waveguide segment 2531 and the third transmission waveguide segment 2533 are located on the substrate 251 and are in a fixed state. The second transmission waveguide segment 2532 is a suspended segment of the transmission waveguide, not located on the substrate 251, and its four sides are all air medium, so it is in a suspended state and can vibrate freely.

[0058] Furthermore, at least the suspended section of the transmission waveguide, i.e. the second transmission waveguide section 2532, is a strip waveguide, which has a guided mode at the operating wavelength, preferably a single guided mode.

[0059] Furthermore, the transmission waveguide is a strip waveguide, which has a guided mode at the operating wavelength, preferably a single guided mode.

[0060] In some embodiments, the first transmission waveguide segment 2531 and the third transmission waveguide segment 2533 are L-shaped, i.e., they are composed of two mutually perpendicular transmission waveguide segments.

[0061] Furthermore, the cross-section of the transmission waveguide core is rectangular.

[0062] Furthermore, the length of the suspended section of the transmission waveguide is much greater than the two side lengths of the cross-section of the core layer of the suspended section of the transmission waveguide. Preferably, the length of the suspended section of the transmission waveguide is greater than 1000 times the two side lengths of the cross-section of the core layer of the transmission waveguide.

[0063] The cross-sectional dimensions of the suspended section of the transmission waveguide are in the nanometer range, and the length of the suspended section is in the micrometer range.

[0064] Furthermore, the coupling waveguide 254 includes at least one coupling sub-waveguide 2541, each coupling sub-waveguide 2541 being located beside the suspended section of the transmission waveguide. When there are multiple coupling sub-waveguides 2541, the multiple coupling sub-waveguides 2541 are identical. The multiple coupling sub-waveguides 2541 are arranged sequentially at intervals along the transmission direction of light in the suspended section of the transmission waveguide, forming a straight line, so that the laser in the suspended section of the transmission waveguide exchanges light energy with each coupling sub-waveguide 2541 sequentially due to the optical coupling effect.

[0065] The coupling waveguide 254 employs a structure of N coupled sub-waveguides 2541 to enhance detection sensitivity. In this invention, a coupling waveguide 254 is placed next to the suspended section of a straight transmission waveguide. Mechanical vibration causes dynamic changes in the spacing between the suspended section of the transmission waveguide and the coupling waveguide 254. These changes alter the optical coupling characteristics between the suspended section of the transmission waveguide and the coupling waveguide 254. The coupling waveguide 254 is designed as a group of N identical coupled sub-waveguides 2541 arranged in a line. The optical signal in the suspended section of the transmission waveguide will sequentially couple with each coupled sub-waveguide 2541. When the input signal in the suspended section of the transmission waveguide is Pin, after passing through the first coupled sub-waveguide 2541, the output signal is αP. in The output signal is then used as the input signal again. After passing through the second coupled sub-waveguide 2541, the output signal is α. 2 P in Similarly, after passing through N identical coupled sub-waveguides 2541, the final output signal is α. N P in When thermomechanical vibration causes a change in the transmission characteristics of the system, after passing through the first coupled sub-waveguide 2541, the output signal is (α+Δα)P. in After passing through N identical coupled sub-waveguides 2541, the final output signal is (α+Δα). N P in . Since α>>Δα, (α+Δα) N P in ≈(α N Therefore, the system transmission change caused by thermomechanical vibration is Δα·N·P, which is N times higher than that of using a single coupled waveguide 254, thus improving the detection sensitivity.

[0066] Furthermore, each coupled sub-waveguide 2541 and the suspended section of the transmission waveguide are located on the same horizontal plane, and each coupled sub-waveguide 2541 and the suspended section of the transmission waveguide are arranged in parallel at intervals.

[0067] In some embodiments, the number of coupler subwaveguides 2541 is 10.

[0068] Furthermore, the coupled sub-waveguide 2541 is a straight strip waveguide, which has a guided mode at the operating wavelength, preferably a single guided mode.

[0069] Furthermore, the spacing between two adjacent coupled subwaveguides 2541 is greater than twice the operating wavelength.

[0070] Furthermore, the coupling length between the coupler sub-waveguide 2541 and the suspended section of the transmission waveguide is Lc (at absolute zero), and the length of the coupler sub-waveguide 2541 is set to twice Lc. This means that at absolute zero, the suspended section of the transmission waveguide does not experience thermomechanical vibration, and light will be coupled from the suspended section of the transmission waveguide into the coupler sub-waveguide 2541, and then completely coupled back from the coupler sub-waveguide 2541 into the suspended section of the transmission waveguide.

[0071] Furthermore, the horizontal spacing between each coupled subwaveguide 2541 and the suspended segment of the transmission waveguide is greater than 10 nanometers and less than 100 nanometers.

[0072] Figure 8 The results show that when the designed spacing between the suspended section of the transmission waveguide and the coupler sub-waveguide 2541 is 50 nm, and the length of the coupler sub-waveguide 2541 is twice Lc (at absolute zero), the thermomechanical vibration of the suspended section of the transmission waveguide causes a change in the spacing between them (ranging from 40 nm to 60 nm). This change in spacing leads to a change in the relative output optical power. The maximum relative output power is obtained at absolute zero. When the thermomechanical vibration causes the spacing to deviate from the designed value of 50 nm, the relative output power decreases.

[0073] The laser light enters the temperature detection device 2 through the fiber optic input interface 21, passes through the input fiber 22, the input port of the silicon waveguide 25, the first transmission waveguide segment 2531, the second transmission waveguide segment 2532 and coupling waveguide 254, the third transmission waveguide segment 2533, the output port of the silicon waveguide 25, and the output fiber 23, and is finally output through the output interface into the photoelectric conversion module 3. In the suspended section of the transmission waveguide, the laser light is optically coupled sequentially with N coupling sub-waveguides 2541. N is greater than or equal to 1. N is a positive integer.

[0074] As the Nth optical coupling occurs, the influence of temperature on the optical coupling between the suspended section of the transmission waveguide and the coupling waveguide 254 will continue to increase, and the fluctuation amplitude of the output power will continue to increase. Figure 9 The diagram shows the variation in the amplitude of the relative output optical power fluctuation in the suspended section of the transmission waveguide at N=10 and temperatures ranging from 1K to 100K. It is easy to observe that at extremely low temperatures, the amplitude of the relative output power fluctuation is minimal. The higher the temperature, the stronger the thermomechanical vibration of the suspended section of the transmission waveguide, and the greater the amplitude of the output power fluctuation.

[0075] The laser emitted by laser source 1 is a continuous, constant-power optical signal. Since the optical coupling between the suspended section of the transmission waveguide and the coupling waveguide 254 changes in real time, the output optical signal of the transmission waveguide will also be a real-time changing optical signal. This real-time change originates solely from the thermomechanical vibration of the suspended section of the transmission waveguide and is unrelated to light transmission. This is because the total length of the coupling waveguide 254 is on the order of tens of micrometers, and the time it takes for light to pass through the entire coupling waveguide 254 is much shorter than the time of one cycle of the mechanical vibration of the suspended section of the transmission waveguide. Therefore, for any input optical signal at any given moment, the coupling waveguide 254 is relatively stationary during its passage through it, and its coupling characteristics remain almost unchanged.

[0076] The above solution will be described in detail below through specific embodiments.

[0077] The silicon waveguide 25 of the present invention has a two-layer structure: a substrate 251 layer and a silicon core layer. The core layer of the optical waveguide is located in the silicon core layer, and light is transmitted in the silicon core layer.

[0078] In this embodiment, the substrate 251 is a silicon dioxide substrate with a silicon core layer thickness of 220 nanometers.

[0079] The transmission waveguide is divided into three segments. The core layer of the first transmission waveguide segment 2531 and the third transmission waveguide segment 2533 has a cross-sectional width W of 300 nm and a height H of 220 nm. The core layer of the second transmission waveguide segment 2532 has a cross-sectional width W of 300 nm and a height H of 220 nm. The length of the second transmission waveguide segment 2532 is 900 μm. The distance between the second transmission waveguide segment 2532 and the underlying substrate 251 is 300 nm.

[0080] The coupling waveguide 254 and the second transmission waveguide segment 2532 are parallel to each other on the same horizontal plane, with a horizontal distance of 50 nanometers between them, resulting in optical energy exchange due to optical coupling effect.

[0081] The coupled waveguide 254 is composed of a row of 10 identical coupled sub-waveguides 2541. Each coupled sub-waveguide 2541 is a straight strip waveguide (with a rectangular cross-section), and all coupled sub-waveguides 2541 are arranged in a straight line. The spacing between any two adjacent coupled sub-waveguides 2541 is 4000 nm. The cross-sectional width of each coupled sub-waveguide 2541 is 300 nm, the height is 220 nm, and the length is 2092 nm.

[0082] Example 2

[0083] like Figure 1As shown in the figure, this embodiment of the invention also discloses a laser cryogenic monitoring system, including a laser source 1, a photoelectric conversion module 3, a signal acquisition card 4, a computer system 5, and a temperature detection device 2 as described in Embodiment 1. The laser source 1 is used to emit laser light; the temperature detection device 2 is used to receive the laser light emitted by the laser source 1 and output the real-time changing light signal to the photoelectric conversion module 3; the photoelectric conversion module 3 is used to convert the real-time changing light signal into an electrical signal and output the electrical signal to the signal acquisition card 4; the signal acquisition card 4 is used to acquire the electrical signal and output the signal data to the computer system 5; the computer system 5 is used to calculate and analyze the signal data to obtain the temperature monitored by the temperature detection module.

[0084] Furthermore, computer system 5 is used to calculate the standard deviation of the signal data, and calculates the temperature to be monitored based on the correspondence between the standard deviation of the signal data and the temperature. Figure 10 The standard deviation of the signal at different temperatures is displayed. The higher the temperature, the larger the standard deviation of the signal. This correspondence between temperature and signal standard deviation allows the temperature of the monitoring system to be monitored.

[0085] In some embodiments, the laser source 1 is a constant power laser source 1 with a wavelength of 1550 nanometers.

[0086] The laser light enters the temperature detection device 2 through the fiber optic input interface 21, passes through the input fiber 22, the waveguide input port, the combined waveguide consisting of the first transmission waveguide segment 2531, the second transmission waveguide segment 2532 and the coupling waveguide 254, the third transmission waveguide segment 2533, the waveguide output port, and the output fiber optic cable 23, and is finally output through the fiber optic output interface 24. It then enters the photoelectric conversion module 3, which converts the real-time changing optical signal into an electrical signal. The signal acquisition card 4 acquires the electrical signal output by the photoelectric conversion module 3 and outputs the signal data to the computer. The computer analyzes the standard deviation of the signal data and calculates the temperature monitored by the temperature detection device 2 based on the correspondence between the standard deviation of the signal data and the temperature.

[0087] Example 3

[0088] This invention also discloses a temperature detection method, which is implemented using the temperature detection device described in Embodiment 1, and includes the following steps:

[0089] The waveguide input port receives light and outputs it to the transmission waveguide. The light propagates in the transmission waveguide and is coupled into the coupling waveguide from the suspended section of the transmission waveguide, and then coupled back into the suspended section of the transmission waveguide from the coupling waveguide. The molecular thermal motion in the suspended section of the transmission waveguide causes thermomechanical vibration in the suspended section of the transmission waveguide. The thermomechanical vibration of the suspended section of the transmission waveguide causes the distance between the suspended section of the transmission waveguide and the coupling waveguide to change dynamically in real time. The dynamic change in the distance between the suspended section of the transmission waveguide and the coupling waveguide causes the optical coupling energy exchange between the suspended section of the transmission waveguide and the coupling waveguide to change dynamically in real time, which in turn causes the optical signal output from the waveguide output port to change dynamically in real time.

[0090] The required temperature is monitored by monitoring changes in the optical signal output from the waveguide output port.

[0091] Monitoring the change in the optical signal output from the waveguide output port to monitor the required temperature specifically includes: converting the real-time changing optical signal into an electrical signal, converting the electrical signal into signal data, analyzing the standard deviation of the signal data, and calculating the monitored temperature based on the correspondence between the standard deviation of the signal data and the temperature.

[0092] The principle of monitoring temperature through the standard deviation of a signal is as follows: The suspended section of the transmission waveguide undergoes thermomechanical vibration. This vibration causes the spacing between the suspended section and the coupling waveguide 254 to change in real time. The transmission of the optical signal in the silicon waveguide 25 is directly related to this spacing, ultimately generating an optical output signal that changes in real time with the thermomechanical vibration. The higher the system temperature, the greater the amplitude of the thermomechanical vibration in the suspended section of the transmission waveguide, the greater the change in the spacing between the suspended section and the coupling waveguide 254, the greater the fluctuations in the output optical signal, and the greater the standard deviation of the signal. Monitoring the standard deviation of the signal is a statistical method that better reflects the characteristics of molecular thermal motion, offering higher robustness compared to monitoring the absolute amplitude of the output signal.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A temperature detection device, comprising a silicon waveguide, characterized in that: The silicon waveguide includes a transmission waveguide and a coupling waveguide. One end of the transmission waveguide is connected to a waveguide input port, and the other end is connected to a waveguide output port. The waveguide input port, waveguide output port, and coupling waveguide are respectively disposed on a substrate. The transmission waveguide is at least partially in a suspended state that can vibrate freely. The ratio of the length of the suspended section of the transmission waveguide to the cross-sectional dimension of the transmission waveguide core layer is greater than 1000. The cross-section of the transmission waveguide core layer is rectangular, and the cross-sectional dimension of the transmission waveguide core layer refers to the side length of the cross-section of the transmission waveguide core layer. There is a horizontal distance between the suspended section of the transmission waveguide and the coupling waveguide, and there is an optical energy exchange between the two due to the optical coupling effect. At temperatures not at absolute zero, the molecular thermal motion of the suspended segment of the transmission waveguide causes thermomechanical vibration in the suspended segment, resulting in a real-time dynamic change in the distance between the suspended segment of the transmission waveguide and the coupled waveguide. This leads to a real-time change in the optical coupling energy exchange between the suspended segment of the transmission waveguide and the coupled waveguide, and consequently, a real-time dynamic change in the optical signal output from the waveguide output port.

2. The temperature detection device as described in claim 1, characterized in that: The suspended sections of the coupled waveguide and the transmission waveguide are parallel to each other on the same horizontal plane, and the horizontal distance between the suspended sections of the coupled waveguide and the transmission waveguide is greater than 10 nanometers and less than 100 nanometers.

3. The temperature detection device as described in claim 1, characterized in that: A groove is provided on the substrate directly below the suspended section of the transmission waveguide, so that the suspended section of the transmission waveguide is in a suspended state.

4. The temperature detection device as described in claim 1, characterized in that: It also includes an input optical fiber and an output optical fiber. One end of the input optical fiber is connected to the waveguide input port, and the other end of the input optical fiber is connected to the optical fiber input interface. One end of the output optical fiber is connected to the waveguide output port, and the other end of the output optical fiber is connected to the optical fiber output interface.

5. The temperature detection device as described in claim 1, characterized in that: The transmission waveguide includes a first transmission waveguide segment, a second transmission waveguide segment, and a third transmission waveguide segment. One end of the first transmission waveguide segment is connected to the waveguide input port, the other end of the first transmission waveguide segment is connected to one end of the second transmission waveguide segment, the other end of the second transmission waveguide segment is connected to one end of the third transmission waveguide segment, and the other end of the third transmission waveguide segment is connected to the waveguide output port. The first and third transmission waveguide segments are disposed on the substrate, and the second transmission waveguide segment is a suspended segment of the transmission waveguide and is in a suspended state.

6. The temperature detection device as described in claim 1, characterized in that: The coupled waveguide includes at least one coupled sub-waveguide, each coupled sub-waveguide being located beside the suspended section of the transmission waveguide. When there are multiple coupled sub-waveguides, the multiple coupled sub-waveguides are arranged sequentially and at intervals along the transmission direction of light in the suspended section of the transmission waveguide, so that the laser in the suspended section of the transmission waveguide exchanges optical energy with each coupled sub-waveguide in turn due to optical coupling effect. The spacing between two adjacent coupled subwaveguides is greater than twice the operating wavelength.

7. The temperature detection device as described in claim 6, characterized in that: When absolute zero, the coupling length of the optical coupling between the sub-waveguide and the suspended section of the transmission waveguide is Lc, then the length of the sub-waveguide is set to twice Lc.

8. The temperature detection device as described in claim 6, characterized in that: The coupler waveguide is a straight strip waveguide, and a guided mode exists at the operating wavelength; at least the suspended section of the transmission waveguide is a strip waveguide, and a guided mode exists at the operating wavelength.

9. A laser cryogenic monitoring system, characterized in that: The system includes a laser source, a photoelectric conversion module, a signal acquisition card, a computer system, and a temperature detection device as described in any one of claims 1 to 8. The laser source is used to emit laser light; the temperature detection device is used to receive the laser light emitted by the laser source and output the real-time changing light signal to the photoelectric conversion module; the photoelectric conversion module is used to convert the input light signal into an electrical signal and output the electrical signal to the signal acquisition card; the signal acquisition card is used to acquire the electrical signal and output the signal data to the computer system; the computer system is used to calculate the standard deviation of the signal data and calculate the temperature to be monitored based on the correspondence between the standard deviation of the signal data and the temperature.

10. A temperature detection method, characterized in that, The temperature detection device described in any one of claims 1 to 8 is used, and the process includes the following steps: The waveguide input port receives light and outputs it to the transmission waveguide. The light propagates in the transmission waveguide and is coupled into the coupling waveguide from the suspended section of the transmission waveguide, and then coupled back into the suspended section of the transmission waveguide from the coupling waveguide. The molecular thermal motion in the suspended section of the transmission waveguide causes thermomechanical vibration in the suspended section of the transmission waveguide. The thermomechanical vibration of the suspended section of the transmission waveguide causes the distance between the suspended section of the transmission waveguide and the coupling waveguide to change dynamically in real time. The dynamic change in the distance between the suspended section of the transmission waveguide and the coupling waveguide causes the optical coupling energy exchange between the suspended section of the transmission waveguide and the coupling waveguide to change dynamically in real time, which in turn causes the optical signal output from the waveguide output port to change dynamically in real time. The required temperature is monitored by monitoring changes in the optical signal output from the waveguide output port.

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