An integrated optical waveguide device, endoscope probe and all-optical photoacoustic endoscope sensing system

Abstract

The present invention discloses an integrated optical waveguide device, an endoscope probe and an all-optical photoacoustic endoscope sensing system, wherein the core layer of the integrated optical waveguide device includes a wave splitter, a first wavelength transmission area and a sensing reflection area connected to the wave splitter in sequence along the light transmission direction; the wave splitter is used to separate light of different wavelengths; the first wavelength transmission area is used to realize the transmission of pulsed light; the sensing reflection area is used to simultaneously realize the transmission, reflection or resonance of a preset wavelength optical signal, and monitor the change of the resonant wavelength or the reflection wavelength, and then monitor the change of environmental parameters. In the endoscope probe, the sensing light signal and the pulse light signal share a double-clad optical fiber, making the endoscope probe more compact. The integrated optical waveguide device of the present invention can realize signal and function separation, and the endoscope probe including the integrated optical waveguide device has high sensitivity, high longitudinal resolution, small size, high integration, and can be used in narrow spaces such as inner cavities.

Description

Technical Field

[0001] The present invention relates to the field of photoacoustic endoscopic imaging, and more specifically, to an integrated optical waveguide device, an endoscopic probe and an all-optical photoacoustic endoscopic sensing system. Background Art

[0002] Early diagnosis and treatment at the early stage of major diseases is an effective means to improve the cure rate of major diseases, reduce the economic burden of patients and reduce pain. With the development of optical imaging technology, photoacoustic imaging (PAI) is a new type of non-destructive, non-invasive and highly sensitive medical imaging technology. Photoacoustic detection is an important technology in PAI, which is realized by using ultrasonic transducers. In the cavity, the complex application environment of PAI combined with optical fiber endoscopy (PAE) puts forward higher and higher requirements for the miniaturization of piezoelectric transducers, which also promotes the development of piezoelectric transducers. The sensitivity of piezoelectric transducers is proportional to the square of the device size, and the detection limit is inversely proportional to the device size. Piezoelectric transducers have a higher detection limit, resulting in image noise. In addition, the opacity of piezoelectric transducers also needs to be further miniaturized in the design of PAE, which will limit the sensitivity and detection frequency bandwidth of PAE. In addition, ultrasound or photoacoustic sensing and pulse light transmission are different. The endoscopy transmitted in optical fibers or media also leads to an increase in the size of the endoscopy. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention proposes an integrated optical waveguide device, an endoscope probe and an all-optical photoacoustic endoscope sensing system. The integrated optical waveguide device can realize the demultiplexing of tunable optical signals and pulsed optical signals, realize the respective functions of optical signals, and use a reflector to output the tunable optical signal carrying sensing information. The use of a waveguide with a high refractive index difference makes the structure size more compact. The endoscope probe made of the integrated optical waveguide device has a more compact structure, high space utilization, can be mass-produced, has a high repetition rate, high sensitivity, high longitudinal resolution, small size, high integration, and can be used in narrow spaces such as inner cavities, thereby expanding the application scope of PAE.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] An integrated optical waveguide device, wherein the refractive index of the core layer is greater than the refractive index of the cladding layer;

[0006] and,

[0007] When the refractive index of the substrate is less than the refractive index of the core layer, the substrate, the cladding layer and the core layer are included in order from bottom to top;

[0008] When the refractive index of the substrate is not less than the refractive index of the core layer, the substrate, the buffer layer, the cladding layer and the core layer are included in order from bottom to top; the refractive index of the buffer layer is less than the refractive index of the core layer;

[0009] The core layer includes a wave splitter, a first wavelength transmission area and a sensing reflection area connected to the wave splitter in sequence along the light transmission direction;

[0010] The wavelength splitter is used to separate light of different wavelengths;

[0011] The first wavelength transmission region is used to realize the transmission of pulsed light;

[0012] The sensing reflection area is used to simultaneously realize the transmission, reflection or resonance of a light signal of a preset wavelength, and monitor the change of the resonant wavelength or the reflected wavelength, and further monitor the change of the environmental parameters.

[0013] Further, the first wavelength transmission region is a pulse light transmission waveguide;

[0014] The sensing reflection area is implemented in any one of the following ways:

[0015] (1) The sensing reflection area includes a sensing structure of a straight waveguide and a cascade of N microrings with different resonant wavelengths, and a reflective device for changing the direction of light transmission; N>1, N is an integer; the diameter of each microring is different;

[0016] (2) The sensing reflection area includes a sensing structure of a cascade of N asymmetric Mach-Zehnder interferometers with different resonant wavelengths, and a reflective device for changing the direction of light transmission; N>1, N is an integer;

[0017] (3) The sensing reflection area includes a sensing reflection structure of N cascaded Bragg gratings with different reflection wavelengths; N>1, N is an integer.

[0018] Further, the first wavelength transmission region includes a pulse light transmission waveguide and a grating coupler;

[0019] The sensing reflection area is implemented in any one of the following ways:

[0020] (1) The sensing reflection area includes a sensing structure of a straight waveguide and a cascade of N microrings with different resonant wavelengths, and a reflective device for changing the direction of light transmission; N>1, N is an integer; the diameter of each microring is different;

[0021] (2) The sensing reflection area includes a sensing structure of a cascade of N asymmetric Mach-Zehnder interferometers with different resonant wavelengths, and a reflective device for changing the direction of light transmission; N>1, N is an integer;

[0022] (3) The sensing reflection area includes a sensing reflection structure of N cascaded Bragg gratings with different reflection wavelengths; N>1, N is an integer.

[0023] Furthermore, the sensing structure or the sensing reflection structure is spiral-shaped as a whole to make the structure more compact.

[0024] Further, the reflective device for changing the light transmission direction is a Sagnac ring; or,

[0025] The reflective device for changing the light transmission direction is a metal film plated on the output end of the sensing reflection area of ​​the integrated optical waveguide device, so as to ensure that the input and output ends of the integrated optical waveguide device share one port and reduce the device structure.

[0026] By using Sachnack rings or metal film reflective devices, a single optical fiber combined with an integrated optical device can simultaneously realize the wave separation of pulse light signals and tunable light signals, as well as the reverse transmission and reception of tunable light signals carrying photoacoustic signals, making the structure of the endoscopic probe more compact and reducing the size of the endoscopic probe.

[0027] Furthermore, the material of the cladding is selected from any one of flexible PDMS film, BCB film, SU-8 film and Epoclad film. These elastic films can increase the change of the effective refractive index of the waveguide device caused by photoacoustic waves or acoustic waves, thereby obtaining higher detection sensitivity, while protecting the waveguide, reducing damage to the waveguide, waveguide pollution, and transmission loss; the core layer is selected from any one of lithium niobate, Si, Si3N4 and chalcogenide compounds, because these materials have a higher refractive index difference and low transmission loss, so that the integrated optical waveguide device has a more compact structure, can perform ultrasonic detection within a large angle range, and achieve higher sensitivity detection by reducing device loss.

[0028] An endoscopic probe including an integrated optical waveguide device, further comprising a plastic sleeve, a metal spring, a metal sleeve, a single-channel double-clad optical fiber array, and a lateral transmission optical fiber;

[0029] The side transmission optical fiber is selected from any one or more combinations of coreless optical fiber and graded-index multimode optical fiber;

[0030] The metal spring, metal sleeve, and single-channel double-clad optical fiber array are all located inside the plastic sleeve; the integrated optical waveguide device and lateral transmission optical fiber are located inside the metal sleeve;

[0031] One end of the metal spring is fixedly connected to the inner end surface of the plastic sleeve, and the other end is fixedly connected to the metal sleeve; the single-channel double-clad optical fiber array passes through the metal spring, extends into the metal sleeve, and is fixedly connected to one end of the integrated optical waveguide device; the other end of the integrated optical waveguide device is fixedly connected to one end of the lateral transmission optical fiber; the other end of the lateral transmission optical fiber is processed into an inclined plane as a total reflection surface; the total reflection surface is magnetron sputtered or evaporated with a layer of metal film that enhances reflection efficiency.

[0032] An endoscopic probe including an integrated optical waveguide device, further comprising a plastic sleeve, a metal spring, a metal sleeve and a single-channel double-clad optical fiber array;

[0033] The metal spring, metal sleeve and single-channel double-clad optical fiber array are located inside the plastic sleeve; the integrated optical waveguide device is located inside the metal sleeve;

[0034] One end of the metal spring is fixedly connected to the inner end surface of the plastic sleeve, and the other end is fixedly connected to the metal sleeve; the single-channel double-clad optical fiber array passes through the metal spring, extends into the metal sleeve, and is fixedly connected to one end of the integrated optical waveguide device.

[0035] Furthermore, the connection ends of the single-channel double-clad optical fiber array and the integrated optical waveguide device are ground and polished to an angle of 8°.

[0036] An all-optical photoacoustic endoscopy sensing system based on integrated optical waveguide technology includes a laser, an optical fiber polarizer, a polarization controller, an optical fiber circulator, a laser, a combiner, a connector, a photodetector, an amplifier, a data acquisition card, a data processing terminal, and an endoscopy probe;

[0037] The laser 1 is connected to the optical fiber polarizer and polarization controller in sequence;

[0038] The optical fiber circulator comprises a port 1, a port 2 and a port 3 connected in a clockwise direction, and is used to separate the optical signal carrying the photoacoustic signal from the narrowband tunable optical signal input into the optical fiber circulator;

[0039] The polarization controller is connected to the port 1 of the optical fiber circulator, the combiner is connected to the port 2 of the optical fiber circulator, and the port 3 of the optical fiber circulator is connected to the photodetector;

[0040] The input port of the combiner is also connected to the second laser, and the output port of the combiner, the connector, and the endoscope probe are connected in sequence;

[0041] The photoelectric detector, amplifier, data acquisition card, and data processing terminal are connected in sequence. The photoelectric detector is used to convert the optical signal carrying the photoacoustic signal into an electrical signal. The data acquisition card is used to perform analog-to-digital conversion on the voltage signal output by the photoelectric detector and upload it to the data processing terminal. The data processing terminal is used to process the information collected by the data acquisition card to obtain information of the sample.

[0042] The connector has built-in means for rotating and translating the endoscopic probe;

[0043] The laser 1 is a tunable laser or an optical frequency comb, which is used to output an optical signal for detecting the photoacoustic signal, and converts the photoacoustic signal detection into the measurement of the optical signal through the sensing reflection area to improve the performance;

[0044] The second laser is a pulse laser.

[0045] The beneficial effects of the present invention are as follows:

[0046] 1. The input and output of the integrated optical waveguide device of the present invention share one port, which reduces the size; in addition, the integrated optical waveguide device can realize liquid sensing, biomolecule sensing and gas sensing. In addition, it can also be used for the delay and filtering of optical signals in optical communication and microwave photons.

[0047] 2. The present invention adopts an endoscope probe with integrated optical waveguide devices. The photoacoustic optical signal and the pulse optical signal share a double-clad optical fiber. The optical fiber core layer is used to transmit the sensing optical signal, and the optical fiber inner cladding is used to transmit the pulse optical signal. This reduces the size of the endoscope probe. When the device structure and number are the same, the occupied scale is smaller, and the size of the endoscope probe is further reduced. It can be used in a small space such as an inner cavity, thereby expanding the application scope of all-optical PAE. In addition, the endoscope probe using integrated optical waveguide devices can be mass-produced, has a high repetition rate, high sensitivity, high longitudinal resolution, small size, high integration, and low cost.

[0048] 3. Compared with the existing method of using two optical fibers to transmit the sensing light signal and the pulse light signal respectively, the all-optical photoacoustic endoscopy sensing system of the present invention adopts an endoscopy probe with integrated optical waveguide technology. The system adopts an all-optical detection method and combines the advantages of double-clad fiber endoscopes. Through this design, only one optical fiber is needed to simultaneously transmit the sensing light signal and the pulse light signal, and the two light signals are effectively separated at the far end of the endoscopy probe. The optical bandwidth is 10 times the bandwidth of the ultrasound signal. 5times. Compared with traditional piezoelectric detectors, the detection method based on integrated optical waveguide devices allows for more sensitive ultrasonic detection over a wider frequency band, providing a wider detection bandwidth. The high-frequency components in the photoacoustic signal are crucial for achieving high axial resolution of PAE. Higher detection bandwidth improves axial resolution and increases the saturation limit of PAE. The sensitivity of integrated optical devices in detecting pressure changes is proportional to the Q factor and wavelength. Higher Q factors and longer wavelengths help to improve detection sensitivity. For example, by using microring resonance, the effective optical path length is amplified by more than 1,000 times, thereby achieving highly sensitive ultrasonic detection. Therefore, compared with traditional PAE using piezoelectric transducers, the all-optical PAE of the present invention has higher detection sensitivity, low noise equivalent pressure, high longitudinal resolution, and high detection frequency bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of an all-optical photoacoustic endoscopic sensing system based on integrated optical waveguide technology according to an embodiment.

[0050] Figure 2 It is a schematic diagram of the structure of an endoscopic probe with a lateral transmission optical fiber 87, wherein the red dotted line frames the integrated optical waveguide device structure.

[0051] Figure 3 It is a schematic diagram of the structure of an endoscopic probe without the lateral transmission optical fiber 87, wherein the red dotted line frames the integrated optical waveguide device structure.

[0052] Figure 4 Schematic diagram of the cross section of a four-layer integrated optical waveguide device.

[0053] Figure 5 The schematic diagram of the structure of the integrated optical device is a cascade micro-ring 860-1 as a sensing area and a Sagnac ring 860-2 as a reflective device.

[0054] Figure 6 Schematic diagram of the relative position structure of the longitudinal section of the integrated optical device and the lateral transmission optical fiber during testing.

[0055] Figure 7 The grating coupler 860-5 is the pulse light signal output end, the cascade micro-ring 860-1 is the sensing area, and the Sagnac ring is the reflective device integrated optical device structure schematic diagram.

[0056] Figure 8 The schematic diagram of the structure of the integrated optical device is that the grating coupler 860-5 is the pulse light signal output end, the metal film reflector 88, and the cascade micro-ring 860-1 is the sensing area.

[0057] Fig. 9The schematic diagram of the structure of the integrated optical device is that the grating coupler 860-5 is the pulse light signal output end and the cascaded Bragg grating is the sensing reflection area; wherein the red arrow indicates light reflection;

[0058] Fig.10 Schematic diagram of the cross-sectional structure of a three-layer integrated optical device.

[0059] Among them: 1 is laser 1; 2 is fiber polarizer; 3 is fiber polarization controller; 4 is laser 2; 5 is broadband polarization-maintaining fiber circulator; 51 is port 1; 52 is port 2; 53 is port 3; 6 is combiner; 7 is connector; 8 is endoscope; 9 is photodetector; 10 is amplifier; 11 is data acquisition card; 12 is data processing terminal; 81 is plastic sleeve; 82 is metal spring; 83 is metal sleeve; 84 is single-channel double-clad fiber array; 85 is cut hole ; 840 is a glass sleeve; 86 is an integrated optical waveguide device; 87 is a lateral transmission optical fiber; 88 is a metal film reflector; changes the direction of light transmission; 860 is a core layer; 861 is a substrate; 862 is a cladding layer; 863 is a buffer layer; 840 is a glass sleeve; 860-1 is a cascaded microring resonator; 860-2 is a Sagnac ring; 860-3 is a first wavelength transmission zone; 860-4 is a splitter; 860-5 is a grating coupler; 860-6 is a cascaded Bragg grating. DETAILED DESCRIPTION

[0060] To facilitate those skilled in the art to understand the technical content of the present invention, the present invention is further explained below with reference to the accompanying drawings.

[0061] Technical term explanation:

[0062] PDMS, Polydimethylsiloxane;

[0063] BCB, Benzocyclobutene, benzocyclobutene.

[0064] Example 1 All-optical photoacoustic endoscopic sensing system based on integrated optical waveguide technology

[0065] The all-optical photoacoustic endoscopic sensing system of this embodiment is as follows Figure 1 As shown, it includes a laser 1, a fiber polarizer 2, a polarization controller 3, a laser 2 4, a fiber circulator 5, a combiner 6, a connector 7, an endoscopic probe 8, a photodetector 9, an amplifier 10, a data acquisition card 11 and a data processing terminal 12.

[0066] Laser 1, fiber polarizer 2, and polarization controller 3 are connected in sequence; fiber circulator 5 includes port 1 51, port 2 52, and port 3 53 connected in a clockwise direction, which are used to separate the optical signal carrying the photoacoustic signal from the narrowband tunable optical signal input to fiber circulator 5. Polarization controller 3 is connected to port 1 51 of fiber circulator 5, combiner 6 is connected to port 2 52 of fiber circulator 5, and port 3 53 of fiber circulator 5 is connected to photodetector 9. The input port of combiner 6 is also connected to laser 2 4, and the output port of combiner 6, connector 7, and endoscope probe 8 are connected in sequence. Photodetector 9, amplifier 10, data acquisition card 11, and data processing terminal 12 are connected in sequence. Laser 24 is a pulsed laser with a central wavelength of 532nm, or a near-infrared light signal within 600-900nm, which is focused on the sample. The sample absorbs the laser energy, resulting in instantaneous thermoelastic expansion, and then emits ultrasonic waves containing a wide frequency range. These ultrasonic waves are detected to construct an image of the sample's optical absorption contrast. These ultrasonic waves are transmitted to the location of the integrated optical device, causing the geometry and refractive index of the integrated optical waveguide device to change, which in turn causes the effective refractive index of the core mode to change. When the resonant wavelength circulates inside the microring, the optical path length change of the microring is cumulative, and the amplified optical path length change can be quantified by measuring the displacement of the resonant wavelength. Tunable narrowband lasers can convert the resonant wavelength displacement into light intensity modulation. Laser 1 is a tunable laser or optical frequency comb with a central wavelength of 1550nm. It is used to output optical signals for detecting photoacoustic signals. The photoacoustic signal detection is converted into the measurement of optical signals through the sensing reflection area. The photoacoustic or ultrasonic detection sensitivity of the integrated optical waveguide device is proportional to the Q factor of the integrated optical waveguide device and the wavelength output by the tunable laser for resonance, and has higher sensitivity. Since the oscillation speed of light is 10 times the speed of ultrasound, 5 As described above, the detection method based on integrated optical devices can perform highly sensitive ultrasonic or photoacoustic wave detection over a wide frequency band, thereby improving the longitudinal resolution and functional saturation limit of the system.

[0067] The tunable optical signal output from the laser 1 passes through the optical fiber polarizer 2, the polarization controller 3, and the port 51 of the optical fiber circulator 5 in sequence, and is output from the port 52 of the optical fiber circulator 5. It is combined with the pulse optical signal output from the laser 2 4 through the combiner 6 and enters the optical fiber endoscope probe 8 through the connector 7. The pulse light output by the optical fiber endoscope probe 8 irradiates the sample, causing thermal expansion of the sample instantaneously, generating a pressure wave, and is received by the integrated optical waveguide device in the optical fiber endoscope probe 8. The optical signal carrying the pressure wave is transmitted through the endoscope probe 8 and the connector 7 in sequence, and passes through the connector 7, the combiner 6, and the port 52 of the circulator 5 in sequence, and is output from the port 53, enters the photodetector 9 for detection, and passes through the amplifier 10 and the data acquisition card 11. The data processing terminal 12 detects and processes the final resonance wavelength or reflection wavelength offset to obtain the sample tomography information or functional information. At the same time, the connector 7 has a built-in device for rotating and translating the endoscopic probe. The connector 7 is driven to rotate by a DC motor to realize the rotation of the endoscopic probe 8, and the connector can realize linear translation from the proximal end to the distal end of the endoscopic probe 8, so that the endoscopic probe 8 can be pulled back.

[0068] Example 2 Endoscopic probe 1

[0069] like Figure 2 As shown, in this embodiment, the endoscope probe 8 includes a plastic sleeve 81, a metal spring 82, a metal sleeve 83, a single-channel double-clad optical fiber array 84, an integrated optical waveguide device 86 and a lateral transmission optical fiber 87. The plastic sleeve 81 is transparent, and a glass sleeve 840 is sleeved outside the single-channel double-clad optical fiber array 84. A hole 85 is cut on the side of the metal sleeve 83 facing the sample. The lateral transmission optical fiber 87 is selected from any one or more combinations of coreless optical fiber or gradient refractive index multimode optical fiber.

[0070] The integrated optical waveguide device 86 is located at the far end of the endoscope probe 8; the integrated optical waveguide device 86, the lateral transmission optical fiber 87, the glass sleeve 840, and part of the single-channel double-clad optical fiber array 84 are encapsulated in a metal sleeve 83 with a cut hole 85, and the rest of the single-channel double-clad optical fiber array 84 is encapsulated in a metal spring 82 to protect the optical fiber and make the optical fiber flexible. The end of the metal sleeve 83 with a cut hole 85 is connected to the metal spring 82 by brazing. The end of the metal spring 82 is connected to the double-clad optical fiber 84 by brazing. The transparent plastic sleeve 81 encapsulates the entire endoscope probe to prevent the probe from directly contacting the sample during the test, which is used to protect the endoscope probe and is also convenient for disinfection. The far end of the lateral transmission optical fiber 87 is specially processed into an inclined plane as a total reflection surface; a metal film that enhances the reflection efficiency is magnetron sputtered or evaporated on the total reflection surface to achieve lateral irradiation of the sample. The connection of various parts inside the endoscope probe 8 is achieved by UV glue curing.

[0071] In combination with the first embodiment, the working principle of the endoscope probe is as follows: the pulse light from the laser 2 4 is transmitted in the inner cladding of the single-channel double-clad optical fiber array 84 of the endoscope probe 8, the tunable optical signal from the laser 1 is transmitted in the core layer of the single-channel double-clad optical fiber array 84 of the endoscope probe 8, the double-clad optical fiber is coupled with the integrated optical waveguide device 86 through the glass sleeve 840, the pulse light signal and the tunable optical signal passing through the single-channel double-clad optical fiber array 84 are coupled together into the integrated optical waveguide device 86, and are separated by the integrated optical waveguide device, the pulse light signal is output from the integrated optical waveguide device 86 and transmitted to the lateral transmission optical fiber 87, the distal end face of the lateral transmission optical fiber 87 is sintered into a spherical shape by a fiber fusion splicer, and is polished to an angle of 43°-47° on one side of the sintered ball, the total reflection surface is a plane, and in order to reduce aberrations, the light output surface is polished into a plane. In order to further improve the total reflection efficiency, a metal film can be plated on the polished surface used for total reflection. This film can be a chromium or gold film, which is plated in the chamber of the magnetron sputtering instrument and the thermal evaporator, respectively, to enhance the total reflection of the optical signal on the interface. The pulse light output from the side transmission optical fiber 87 passes through the transparent plastic sleeve 81 and irradiates the sample laterally. After the sample absorbs the light of a specific wavelength, heat is generated, resulting in a local temperature rise and thermal expansion of the sample, which excites ultrasonic waves. These ultrasonic waves act on the integrated optical waveguide device 86, causing the integrated optical waveguide device 86 to deform and change its refractive index. These ultrasonic waves are loaded on the tunable optical signal and returned to the core layer of the single-channel double-clad optical fiber array 84 in the endoscope probe 8 for transmission, and returned to the system through the connector 7 for processing.

[0072] Example 3 Endoscopic Probe 2

[0073] like Figure 3 As shown, different from Example 2, the optical fiber part of the endoscope probe 8 of this embodiment only includes a single-channel double-clad optical fiber array 84, and does not include a lateral transmission optical fiber 87, but the integrated optical waveguide device 86 of the endoscope probe 8 is required to contain a grating coupler (such as the following Examples 5, 6, and 7), and the other components and structures are the same as those of Example 2. Its working principle is different from that of Example 2 in that the pulsed optical signal separated by the integrated optical waveguide device 86, the grating diffraction effect of the grating coupler 860-5 in the integrated optical waveguide device 86, irradiates the sample laterally, causing thermal expansion of the sample instantaneously, and the thermal expansion of the sample generates a pressure wave, which acts on the integrated optical waveguide device 86 and is then loaded on the tunable optical signal, and returns to the core layer of the single-channel double-clad optical fiber array 84 in the endoscope probe 8 for transmission, and returns to the system through the connector 7 for processing.

[0074] Example 4 Integrated optical waveguide device 1

[0075] like Figure 4As shown, in this embodiment, the integrated optical waveguide device 86 includes a substrate 861, a buffer layer 863, a core layer 860 and a cladding layer 862 from bottom to top. The material of the core layer 860 is lithium niobate, the material of the substrate 861 is silicon, the cladding layer 862 is PDMS, and the buffer layer 863 is silicon dioxide. Figure 5 As shown, the core layer 860 includes a splitter 860-4, a first wavelength transmission area 860-3 and a sensing reflection area connected to the splitter 860-4 in sequence along the light transmission direction. In this embodiment, the first wavelength transmission area 860-3 is a pulse light transmission waveguide, and the sensing reflection area includes a sensing structure 860-1 composed of a straight waveguide and 8 microrings cascaded, and a reflection area composed of a Sagnac ring 860-2. The resonant wavelengths λ1, λ2, λ3, λ4, λ5, λ6, λ7, and λ8 of the 8 microrings are 1550nm, 1553.2nm, 1556.4nm, 1559.6nm, 1562.8nm, 1546.8nm, 1543.6nm, and 1540.4nm, respectively. The central wavelength of the pulse light transmitted by the pulse light transmission waveguide is 532nm. The pulse light transmission waveguide is connected to the lateral transmission optical fiber 87 of the endoscope probe at the output end of the integrated optical waveguide device 86 through UV glue curing coupling. The connection position is as follows: Figure 6 As shown. The pulsed light output from the side transmission optical fiber 87 irradiates the sample, causing thermal expansion of the sample instantaneously, generating photoacoustic waves. The photoacoustic waves act on the integrated optical waveguide device 86 in the endoscope probe 8 through the intermediate medium, and the pressure wave acts on the 8 microrings, causing the effective refractive index of the cascaded microring resonator to change, thereby causing the resonant wavelength to shift. It passes through the Sachnack ring 860-2 and the 8 microrings again, thereby improving the quality factor Q of the cascaded microrings, with a steeper filtering edge and a narrower pulse width. The returned optical signal passes through the wavelength divider 860-4 and leaves the integrated optical waveguide device 86. The integrated optical waveguide device 86 realizes the conversion of the measurement of photoacoustic waves or acoustic waves into the measurement of the offset of the resonant wavelength. By measuring the offset of the resonant wavelength of the 8 microrings, the pressure wave is measured, and the structural or functional information of the sample is obtained.

[0076] Example 5 Integrated optical waveguide device II

[0077] like Figure 7 As shown, the integrated optical waveguide device 86 of this embodiment is different from that of the fourth embodiment in that the first wavelength transmission region 860-3 includes a grating coupler 860-5 connected to the end of the pulse light transmission waveguide in addition to the pulse light transmission waveguide. Through the grating diffraction effect, the pulse light leaves the integrated optical waveguide device 86 and irradiates the sample. The rest is the same as that of the fourth embodiment.

[0078] Example 6 Integrated optical waveguide device 3

[0079] like Figure 8As shown, the integrated optical waveguide device 86 of this embodiment is different from that of Embodiment 5 in that the Sagnac ring 860-2 in the sensing reflection area is replaced with a metal film reflector 88, which changes the light transmission direction, thereby allowing the optical signal carrying the photoacoustic wave information to be transmitted to the system and demodulated to obtain the structural or functional information of the sample.

[0080] Example 7 Integrated optical waveguide device 4

[0081] like Fig. 9 As shown, the structure of the first wavelength transmission area 860-3 of the integrated optical waveguide device 86 of this embodiment is the same as that of embodiments 5 and 6, but the sensing reflection area is a cascaded Bragg grating 860-6. The reflection wavelengths λ1, λ2, λ3, λ4, λ5, and λ6 of the six cascaded Bragg gratings are 1550nm, 1556.4nm, 1562.8nm, 1569.2nm, 1543.6nm, and 1537.2nm, respectively. The pulse light irradiates the sample, causing thermal expansion of the sample instantaneously, generating photoacoustic waves, which act on the sensing reflection area in the endoscope probe 8 through the intermediate medium, causing the effective refractive index of the integrated optical waveguide device 86 to change, thereby causing the reflection wavelength of the six cascaded Bragg gratings 860-6 to change. At this time, the measurement of the photoacoustic wave or the sound wave has been converted into the measurement of the offset of the reflection wavelength. By measuring the offset of the reflection wavelength of the six Bragg gratings, the pressure wave acting on the integrated optical waveguide device is measured, thereby obtaining the structural or functional information of the sample.

[0082] Example 8 Integrated optical waveguide device 5

[0083] like Fig.10 As shown, the integrated optical waveguide device 86 in this embodiment includes a substrate 861, a core layer 860 and a cladding layer 862 from bottom to top. Among them, the material of the core layer 860 is lithium niobate, the material of the substrate 861 is silicon dioxide, and the material of the cladding layer 862 is PDMS. The structure on the core layer is the same as that of Example 4.

[0084] Those skilled in the art will note that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of the claims of the present invention.

Claims

1. An integrated optical waveguide device, characterized in that: The refractive index of the core is greater than that of the cladding; and, When the refractive index of the substrate is less than the refractive index of the core layer, the substrate, the cladding layer and the core layer are included in order from bottom to top; When the refractive index of the substrate is not less than the refractive index of the core layer, the substrate, the buffer layer, the cladding layer and the core layer are included in order from bottom to top; the refractive index of the buffer layer is less than the refractive index of the core layer; The core layer includes a wave splitter, a first wavelength transmission area and a sensing reflection area connected to the wave splitter in sequence along the light transmission direction; The wavelength splitter is used to separate light of different wavelengths; The first wavelength transmission region is used to realize the transmission of pulsed light; The sensing reflection area is used to simultaneously realize the transmission, reflection or resonance of a light signal of a preset wavelength, and monitor the change of the resonant wavelength or the reflected wavelength, and further monitor the change of the environmental parameters.

2. The integrated optical waveguide device according to claim 1, characterized in that: The first wavelength transmission region is a pulse light transmission waveguide; The sensing reflection area is implemented in any one of the following ways: (1) The sensing reflection area includes a sensing structure of a straight waveguide and a cascade of N microrings with different resonant wavelengths, and a reflective device for changing the direction of light transmission; N>1, N is an integer; the diameter of each microring is different; (2) The sensing reflection area includes a cascade sensing structure consisting of N asymmetric Mach-Zehnder interferometers with different resonant wavelengths, and a reflective device for changing the direction of light transmission; N>1, N is an integer; (3) The sensing reflection area includes a sensing reflection structure of N cascaded Bragg gratings with different reflection wavelengths; N>1, N is an integer.

3. The integrated optical waveguide device according to claim 1, characterized in that: The first wavelength transmission region includes a pulse light transmission waveguide and a grating coupler; The sensing reflection area is implemented in any one of the following ways: (1) The sensing reflection area includes a sensing structure of a straight waveguide and a cascade of N microrings with different resonant wavelengths, and a reflective device for changing the direction of light transmission; N>1, N is an integer; the diameter of each microring is different; (2) The sensing reflection area includes a sensing structure of a cascade of N asymmetric Mach-Zehnder interferometers with different resonant wavelengths, and a reflective device for changing the direction of light transmission; N>1, N is an integer; (3) The sensing reflection area includes a sensing reflection structure of N cascaded Bragg gratings with different reflection wavelengths; N>1, N is an integer.

4. The integrated optical waveguide device according to claim 2 or 3, characterized in that: The sensing structure or the sensing reflection structure is spiral-shaped as a whole, so as to make the structure more compact.

5. The integrated optical waveguide device according to claim 2 or 3, characterized in that: The reflective device for changing the light transmission direction is a Sagnac ring; or, The reflective device for changing the light transmission direction is a metal film plated on the output end of the sensing reflection area of ​​the integrated optical waveguide device, so as to ensure that the input and output ends of the integrated optical waveguide device share one port and reduce the device structure.

6. The integrated optical waveguide device according to claim 1, characterized in that: The material of the cladding layer is selected from any one of a flexible PDMS film, a BCB film, a SU-8 film and an Epoclad film; and the core layer is selected from any one of lithium niobate, Si, Si3N4 and a chalcogenide.

7. An endoscopic probe comprising the integrated optical waveguide device according to claim 2, characterized in that: Also included are a plastic sleeve, a metal spring, a metal sleeve, a single-channel double-clad optical fiber array, and a side-transmission optical fiber; The side transmission optical fiber is selected from any one or more combinations of coreless optical fiber and graded-index multimode optical fiber; The metal spring, metal sleeve, and single-channel double-clad optical fiber array are all located inside the plastic sleeve; the integrated optical waveguide device and lateral transmission optical fiber are located inside the metal sleeve; One end of the metal spring is fixedly connected to the inner end surface of the plastic sleeve, and the other end is fixedly connected to the metal sleeve; the single-channel double-clad optical fiber array passes through the metal spring, extends into the metal sleeve, and is fixedly connected to one end of the integrated optical waveguide device; the other end of the integrated optical waveguide device is fixedly connected to one end of the lateral transmission optical fiber; the other end of the lateral transmission optical fiber is processed into an inclined plane as a total reflection surface; the total reflection surface is magnetron sputtered or evaporated with a layer of metal film that enhances reflection efficiency.

8. An endoscopic probe comprising the integrated optical waveguide device according to claim 3, characterized in that: Also included are a plastic sleeve, a metal spring, a metal sleeve, and a single-channel double-clad optical fiber array; The metal spring, metal sleeve and single-channel double-clad optical fiber array are located inside the plastic sleeve; the integrated optical waveguide device is located inside the metal sleeve; One end of the metal spring is fixedly connected to the inner end surface of the plastic sleeve, and the other end is fixedly connected to the metal sleeve; the single-channel double-clad optical fiber array passes through the metal spring, extends into the metal sleeve, and is fixedly connected to one end of the integrated optical waveguide device.

9. The endoscopic probe according to claim 7 or 8, characterized in that: The connecting ends of the single-channel double-clad optical fiber array and the integrated optical waveguide device are ground and polished to an angle of 8°.

10. An all-optical photoacoustic endoscopic sensing system based on integrated optical waveguide technology, characterized in that: It comprises a laser 1, a fiber polarizer, a polarization controller, a fiber circulator, a laser 2, a combiner, a connector, a photodetector, an amplifier, a data acquisition card, a data processing terminal, and the endoscope probe according to claim 7 or 8; The laser 1 is connected to the optical fiber polarizer and polarization controller in sequence; The optical fiber circulator comprises a port 1, a port 2 and a port 3 connected in a clockwise direction, and is used to separate the optical signal carrying the photoacoustic signal from the narrowband tunable optical signal input into the optical fiber circulator; The polarization controller is connected to the port 1 of the optical fiber circulator, the combiner is connected to the port 2 of the optical fiber circulator, and the port 3 of the optical fiber circulator is connected to the photodetector; The input port of the combiner is also connected to the second laser, and the output port of the combiner, the connector, and the endoscope probe are connected in sequence; The photoelectric detector, amplifier, data acquisition card, and data processing terminal are connected in sequence. The photoelectric detector is used to convert the optical signal carrying the photoacoustic signal into an electrical signal. The data acquisition card is used to perform analog-to-digital conversion on the voltage signal output by the photoelectric detector and upload it to the data processing terminal. The data processing terminal is used to process the information collected by the data acquisition card to obtain information of the sample. The connector has built-in means for rotating and translating the endoscopic probe; The laser 1 is a tunable laser or an optical frequency comb, which is used to output an optical signal for detecting the photoacoustic signal, and converts the photoacoustic signal detection into the measurement of the optical signal through the sensing reflection area to improve the performance; The second laser is a pulse laser.

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