Optical sensor circuit and optical sensing method

Abstract

The optical sensor circuit (10) is an optical circuit for routing input optical signals through an array of optical sensors (S1, S2, S3, S4). An optical sensor circuit (10) includes an input port (16) for receiving a plurality of input optical signals within a single input channel. A wavelength division demultiplexer (22) is coupled to the input port (16) to demultiplex the plurality of input optical signals, and a plurality of optical sensors (S1, S2, S3, S4) are coupled to the wavelength division demultiplexer (22) for receiving the plurality of input optical signals and outputting a plurality of output optical signals. A wavelength division multiplexer (24) is coupled to the plurality of optical sensors (S1, S2, S3, S4) to multiplex the plurality of output optical signals into a single output channel. An output port (18) is coupled to the wavelength division multiplexer (24) for outputting an output optical signal in a single output channel.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 443,105, filed on February 3, 2023, entitled “Optical Sensor Circuit and Optical Sensing Method,” U.S. Provisional Patent Application No. 63 / 592,482, filed on October 23, 2023, entitled “Mixed Transducer Array with Fiber Sensors,” U.S. Provisional Patent Application No. 63 / 450,554, filed on March 7, 2023, entitled “Mixed Array Imaging Probe,” and U.S. Provisional Patent Application No. 63 / 545,327, filed on October 23, 2023, entitled “Miniature Mixed Array Imaging Probe,” each of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to optical sensing, and in particular to optical sensor circuits for routing input optical signals through optical sensor arrays, such as, for example but not limited to, photoacoustic sensors or multi-dimensional optical sensors. Background Art

[0004] Acoustic or ultrasonic technology is used in various industries, especially in non-invasive measurement, remote sensing and imaging. In medical applications, ultrasound is used for imaging, treatment, measurement, sensing and diagnostic procedures. In non-medical applications, ultrasound is used for industrial applications for defect detection, non-destructive testing, structural testing and microparticle particle sorting, geological applications (including mining and drilling operations) and underwater marine applications and other applications. Acoustic or ultrasonic technology operates by transmitting an acoustic signal toward an object and detecting the resulting echo signal reflected or generated from the object in response to the transmitted acoustic signal. Ultrasound is an advantageous non-invasive imaging form. By transmitting higher frequency sound waves, the resolution of ultrasound is increased. However, due to the increase in acoustic attenuation, the penetration depth is reduced. This compromise between resolution and penetration depth poses a challenge. The present invention is directed to providing improved ultrasonic technology. Summary of the Invention

[0005] The optical sensor circuit disclosed herein is an optical circuit for routing an input optical signal through an array of optical sensors (such as, for example, but not limited to, a photoacoustic sensor or a multi-dimensional optical sensor). By transmitting multiple input optical signals within a single input channel to an optical input port of the optical sensor circuit, the number of optical fibers and input / output (I / O) ports is reduced. It should be understood that, for example, when the optical sensor is integrated into a photonic integrated circuit (PIC) chip, the I / O port can be an on-chip port, or can be incorporated into any type of optical circuit or optical sensor system.

[0006] In one embodiment, an optical sensor circuit includes an optical input port for receiving multiple input optical signals within a single input channel, wherein each input optical signal has a unique wavelength associated therewith. A wavelength division multiplexer coupled to the optical input port is configured to demultiplex the multiple input optical signals; and multiple optical sensors coupled to the wavelength division multiplexer are configured to receive the multiple input optical signals and output corresponding multiple output optical signals. Each output optical signal can have a unique wavelength associated therewith that matches the wavelength of a corresponding one of the input optical signals. A wavelength division multiplexer is coupled to the multiple optical sensors to multiplex the multiple output optical signals into a single output channel, and an optical output port coupled to the wavelength division multiplexer is configured to output the multiple output optical signals in the single output channel. Thus, the number of optical fibers and I / O ports is reduced. As discussed above, it should be understood that the I / O port can be an on-chip port or a port of any other suitable type of optical circuit or optical sensor system.

[0007] As a non-limiting example, the plurality of optical sensors may be in the form of a fiber optic sensor array. As another non-limiting example, the optical sensor circuit may further include an acoustic transducer. As a further non-limiting example, the optical sensor array and the acoustic transducer may be mounted together in a hybrid sensor transducer probe.

[0008] In an alternative embodiment, multiple optical input ports are provided for respectively receiving multiple input channels. In this embodiment, each input channel carries multiple input optical signals, wherein each input optical signal within each input channel has a unique wavelength associated therewith. A power splitter is in communication with the multiple optical input ports and is configured to split each input channel into multiple sub-channels carrying multiple input optical sub-signals. A wavelength division multiplexer is coupled to the power splitter and is configured to demultiplex each of the multiple input optical sub-signals; and multiple optical sensors are coupled to the wavelength division multiplexer and are configured to respectively receive the multiple input optical sub-signals and output corresponding multiple output optical signals. Each output optical signal can have a unique wavelength associated therewith that matches the wavelength of a corresponding one of the input optical sub-signals. The wavelength division multiplexer is coupled to the multiple optical sensors to multiplex the multiple output optical signals into multiple output channels. Multiple optical output ports are coupled to the wavelength division multiplexer and are configured to output the multiple output optical signals in the multiple output channels. In this embodiment, the total number of the multiple output channels is equal to the total number of output optical signals divided by the total number of input channels.

[0009] Although in the alternative embodiments described above, the wavelength division multiplexer, wavelength division multiplexer, and power splitter may all be integrated within the same photonic integrated circuit (PIC) chip as the optical sensors, it will be appreciated that one or more of these components may be located on a separate optical mid-level chip. Thus, rather than coupling the input and output waveguides directly to the PIC chip via input and output optical ports, the input and output waveguides are coupled to a mid-level chip, which in turn is coupled to the input and output ports on the PIC chip. As discussed above, it will be appreciated that the optical circuitry may be integrated into or include a PIC chip, etc., or alternatively, may form or be part of any other suitable type of optical circuitry or optical sensor system.

[0010] The optical sensor circuit described above can be integrated into a larger photoacoustic sensor system, and it should be understood that such a sensor system does not necessarily require the components discussed above to be integrated into a PIC chip. In one embodiment, the photoacoustic sensor system includes an acoustic probe, such as an ultrasound probe, for delivering acoustic signals to a sample to be sensed, such as a tissue sample, a body part, or the like. Similar to the previous embodiment, a light source is provided for generating multiple input optical signals, each of which has a unique wavelength associated therewith. A wavelength division multiplexer is optically coupled to the light source to demultiplex the multiple input optical signals, and multiple optical sensors are provided for sensing the sample. Multiple optical sensors are optically coupled to the wavelength division multiplexer to respectively receive the multiple input optical signals and output corresponding multiple output optical signals. The wavelength division multiplexer is optically coupled to the multiple optical sensors to multiplex the multiple output optical signals into a single output channel. The single output channel is then processed to generate an image of the sample or data representing a sensed physical parameter. The plurality of optical sensors may be provided as an optical sensor array, and furthermore, a heating source may be provided for selectively heating individual ones of the optical sensors of the optical sensor array for tuning the individual ones of the optical sensors of the optical sensor array.

[0011] These and other features of the present subject matter will become clear upon further review of the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 An optical sensor circuit is schematically illustrated.

[0013] Figure 2 An alternative embodiment of an optical sensor circuit is schematically illustrated.

[0014] Figure 3 An optical sensor system is diagrammatically illustrated.

[0015] Figure 4 Schematically illustrates the Figure 1 and / or Figure 2 An optical sensor system of an optical sensor circuit.

[0016] Figure 5 A photoacoustic sensor system is schematically illustrated.

[0017] Figure 6 An alternative embodiment of a photoacoustic sensor system is schematically illustrated.

[0018] Figure 7 An alternative embodiment of an optical sensor circuit is schematically illustrated.

[0019] Figure 8A and Figure 8BA hybrid sensor transducer probe is illustrated.

[0020] Like reference numerals refer to corresponding features throughout the drawings. DETAILED DESCRIPTION

[0021] Non-limiting examples of various aspects and variations of the present invention are described herein and illustrated in the accompanying drawings. The following detailed description is merely illustrative in nature and is not intended to limit the present invention or its applications and uses. Although the present invention is described in the context of optical sensor systems, methods, and devices for ultrasound imaging, this disclosure should not be construed as limiting. For example, although the methods herein may be discussed with respect to medical ultrasound, their embodiments may be applicable to other medical procedures and other processes or methods in other industries that could benefit from the sensing and imaging techniques described herein. Furthermore, various systems and devices including optical sensors and photonic integrated sensors are described. It should be understood that the optical sensors and photonic integrated sensors described herein may be integrated into and / or used with various systems and devices not described herein. Modifications may be made to the embodiments described herein without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not intended to be limiting. Furthermore, no intention is to be bound by any expressed or implied theory presented in the preceding technical field, background, summary, or the following detailed description.

[0022] Various structures are described herein based on their geometric properties. As discussed herein, all structures described herein may vary from the described shapes based on tolerances of known manufacturing techniques. Unless otherwise indicated, features described using the term "substantially" should be understood to be within 5% of the strictness. For example, features described as "substantially parallel" may deviate from true parallelism by 5%.

[0023] Some existing ultrasound technologies use acoustic energy generation (AEG) materials for transducers to generate and receive acoustic signals. Commonly used AEG transducers include piezoelectric materials such as lead zirconate titanate (PZT), ceramics, piezoelectric single crystals (e.g., PIN-PT, PIN-PMN-PT), polymer thick film (PTF), polyvinylidene fluoride (PVDF), capacitive micromachined ultrasonic transducers (CMUTs), photoacoustic transducers, piezoelectric micromachined ultrasonic transducers (PMUTs), along with many other materials known to those skilled in the art. However, in addition to the trade-off between resolution and penetration depth, some challenges associated with the use of these materials include high operating voltage requirements, high electric field requirements (which can lead to breakdown and failure), nonlinear response with high hysteresis, and limited detection angles. In addition, the detection sensitivity of AEG transducers is a function of size, thereby limiting their applicability to size-constrained applications such as intravascular ultrasound (IVUS) devices.

[0024] Another challenge is the narrow bandwidth of AEG transducers. For example, for ultrasonic transducers made from piezoelectric materials such as lead zirconate titanate (PZT), the 6dB bandwidth of PZT is typically limited to approximately 70%. Certain composite PZT materials have slightly increased bandwidth, but still only achieve bandwidths up to approximately 80%. As another example, single-crystal materials are increasingly being used to improve the performance of ultrasonic probes, but single-crystal materials have a low Curie temperature and are brittle. Another type of transducer material is silicon, which can be processed to construct capacitive micromachined ultrasonic transducer (CMUT) probes that can have increased bandwidth. However, CMUT probes are not very sensitive or reliable. Furthermore, CMUT probes have several operational limitations. For example, CMUT probes are nonlinear transducers and are therefore generally unsuitable for harmonic imaging. Furthermore, CMUT probes require additional bias voltages to operate properly. Consequently, new and improved devices and methods are needed for ultrasonic imaging modes with different frequency harmonics to achieve higher resolution, better penetration, and fewer artifacts than the basic imaging of conventional ultrasonic sensing.

[0025] In many applications, it is desirable to detect multiple physical parameters. For example, in the field of medical technology, it may be advantageous to have a medical device with sensors that can sense multiple different physical parameters (e.g., simultaneously in real time or near real time). For example, an ablation catheter for cardiovascular surgery may include a temperature sensor for measuring the temperature of the treated tissue and a force sensor for measuring the force applied to the artery wall during cardiac ablation. In addition to or in lieu of imaging, multiple sensors may be combined together in a single device to monitor multiple different types of parameters. However, including more sensors may make it more challenging to fit the device into a desired form factor. Additionally or alternatively, including more sensors may cause more difficulties in accommodating additional components (e.g., mechanical and / or electrical) and connections to achieve proper functionality for all the different sensors.

[0026] The use of optical sensors as multidimensional sensors for sensing physical parameters alleviates many of the difficulties associated with combining multiple sensors and their different components and connections. To achieve multidimensional sensing, measurement signals are generated from the optical sensor responses, where each of these measurement signals can be indicative of a corresponding physical signal. For example, a signal processor can generate a temperature measurement signal based at least in part on a resonant frequency shift (e.g., a mode shift) and an acoustic measurement signal based at least in part on an oscillation of optical power. Multidimensional sensing can also be achieved by using multiple sensors, each responding differently to different sensing targets. Variations on generating measurement signals from optical sensor responses can include decoupling individual physical signals and / or jointly analyzing multiple sensor responses to determine individual physical signals.

[0027] Photonic devices and optical pressure sensing technologies have shown great promise for ultrasound detection. In photonic devices, refractive index modulation and / or shape deformation caused by strain induced by acoustic waves is converted into changes in the intensity of detected light or the spectral characteristics of the device. In some existing devices, optical resonators have been used as highly sensitive ultrasound detectors. Typically, the performance of an optical resonator is limited by its quality factor Q (i.e., the higher the Q, the lower the light loss and the smaller the detectable resonance shift), and by the acousto-optical and mechanical properties of the material from which the resonator is made. Compared to other types of ultrasound sensors, optical sensors (such as, for example, whispering galley mode (WGM) optical resonators) can have high sensitivity and wide bandwidth in the reception of ultrasound signals. Due to the high sensitivity and wide bandwidth of the optical sensor, the image generated by the optical sensor can have improved spatial resolution, improved penetration depth, improved signal-to-noise ratio (SNR), improved tissue harmonic imaging and / or improved Doppler sensitivity.

[0028] Acousto-optic systems based on optical sensors can directly measure ultrasound waves (e.g., ultrasound echoes) through the photoelastic effect and / or physical deformation of one or more resonators in response to ultrasound waves (e.g., ultrasound echoes). For example, in the presence of ultrasound (or any pressure) waves, the WGM traveling through an optical resonator can experience a spectral shift caused by changes in the refractive index and shape of the optical resonator. This spectral change can be easily monitored and analyzed in terms of the spectral domain and the intensity of light transmitted to and from the optical resonator. Furthermore, additional spatial and other information can be derived by monitoring and analyzing the shifted WGMs between multiple optical resonators.

[0029] The optical sensors described herein may include interference-based optical sensors, such as optical resonators, optical interferometers, and the like. Optical resonators may include, for example, whispering gallery mode (WGM) optical resonators, microbubble optical resonators, microsphere resonators, microring resonators, microring resonators, microdisk optical resonators, and the like. Optical interferometers may include Mach-Zehnder interferometers, Michelson interferometers, Fabry-Perot interferometers, Sagnac interferometers, and the like. For example, a Mach-Zehnder interferometer may include two nearly identical optical paths (e.g., optical fibers, on-chip silicon waveguides, and the like). The two optical paths may be finely tuned acoustic waves (e.g., physical motion induced by acoustic waves, tuning of refractive index induced by acoustic waves, and the like) to achieve a distribution of optical power in the output of the Mach-Zehnder interferometer, and thus, detect the presence or amplitude of acoustic waves.

[0030] An optical resonator may comprise a closed loop of a transparent medium that allows light of certain permitted frequencies to propagate continuously within the loop and stores the optical energy of the light of these permitted frequencies within the loop. For example, an optical resonator may permit whispering gallery modes (WGMs) to propagate through the concave surface of the optical resonator and, corresponding to the permitted frequencies, circulate the circumference of the resonator. Each mode from the WGM corresponds to the propagation of a frequency of light from the permitted frequencies. The permitted frequencies and quality factors of the optical resonators described herein may be based, at least in part, on the geometric parameters of the optical resonator, the refractive index of the transparent medium, and the refractive index of the environment surrounding the optical resonator.

[0031] Acoustic or ultrasonic capabilities can be categorized based on, among other things, sensitivity, resolution, and field of view. Sensitivity is related to the design and optimization of individual sensor elements. Resolution and field of view are limited by the sensor array configuration, including the spacing between adjacent sensors, the total number of sensors in an imaging probe, and the length and width of the sensor array to cover a sufficient field of view. Therefore, there are challenges in designing robust, efficient acoustic-optical sensors with minimal losses in a desired form factor.

[0032] When designing an optical sensor for physical measurement and / or acoustic detection, several factors must be considered. Optical losses must be minimized, as these losses fundamentally affect the sensor's efficiency. Careful attention is required when designing the coupling gap between the resonator and the waveguide, as well as determining the appropriate waveguide cross-section. Noise must be minimized to optimize the SNR, and various parameters must be balanced, such as laser power, required array size, available space on the chip or array structure, required power, and the number of sensors required, the number of channels required, and the impact of all components along the signal path.

[0033] As will be discussed in detail below, the optical sensor circuit disclosed herein is an optical circuit for routing an input optical signal through an array of optical sensors (such as, for example, but not limited to, photoacoustic sensors and / or optical sensors for sensing physical parameters). The number of optical fibers and on-chip or fiber optic sensor input / output (I / O) ports (cables) is reduced by transmitting multiple input optical signals to the optical input port of the optical sensor circuit within a single input channel. As discussed above, it should be understood that the optical circuit can be integrated into or include a PIC chip or the like, or alternatively, it can form or be part of any other suitable type of optical circuit or optical sensor system.

[0034] like Figure 1As shown, in one embodiment, the optical sensor circuit 10 is an optical circuit for routing an input optical signal through an optical sensor array, such as, but not limited to, a photoacoustic sensor and / or an optical sensor for sensing a physical parameter. Figure 1 As shown, optical sensor circuit 10 includes an optical input port 16 for receiving multiple input optical signals within a single input channel, each having a unique wavelength associated therewith. As a non-limiting example, four laser units 12 can be used to deliver four optical signals at unique wavelengths via a single optical fiber 26 connected to a single input port 16 on a photonic integrated circuit (PIC) chip 14. The four optical signals are transmitted via a single optical fiber to the single input port, which, in this example, reduces the number of required optical fibers and I / O ports. It should be understood that any suitable number of optical signals having unique wavelengths can be used, and the four signals discussed above are merely non-limiting examples. Furthermore, it should be understood that any suitable type of laser can be used to generate the input optical signals, and any suitable type of optical fiber and optical input port can be used. Furthermore, it should be understood that a single optical fiber 26 is shown for exemplary purposes only, and that any suitable type of optical waveguide can be utilized. Furthermore, as discussed above, it should be understood that the optical circuit can be integrated into or include a PIC chip, etc., or alternatively, it can form or be part of any other suitable type of optical circuit or optical sensor system.

[0035] In this non-limiting example, the PIC chip 14 includes a wavelength division multiplexer 22 coupled to the optical input port 16 for demultiplexing a plurality of input optical signals, and a plurality of optical sensors S1, S2, S3, and S4 coupled to the wavelength division multiplexer 22 for respectively receiving the plurality of input optical signals and outputting a corresponding plurality of output optical signals. According to the non-limiting example discussed above, the wavelength division multiplexer 22 separates four optical signals having corresponding wavelengths λ1, λ2, λ3, and λ4 transmitted through a single channel via a single optical fiber 26, and these separate optical signals are input to the optical sensors S1, S2, S3, and S4, respectively, which are also included on the PIC chip 14. It should be understood that the sensors S1, S2, S3, and S4 can be any suitable type of optical sensor, such as, but not limited to, a photoacoustic sensor and / or a multi-dimensional optical sensor. Further, it will be appreciated that any suitable type of optical fiber, waveguide, etc. may be used to couple the wavelength division multiplexer 22 to the array of sensors S1 , S2, S3, S4.

[0036] The output of each sensor S1, S2, S3, S4 typically has the same wavelength as the input signal; that is, in this non-limiting example, the optical signal output from the array of sensors S1, S2, S3, S4 will typically have a corresponding wavelength λ1, λ2, λ3, λ4. As a non-limiting example, if the sensors S1, S2, S3, S4 are photoacoustic sensors, then the output of each sensor can be an optical signal having the same wavelength as the input signal but with an offset phase, and this offset phase will represent the acoustic force sensed by the sensor S1, S2, S3, S4. As another non-limiting example, if the sensors S1, S2, S3, S4 are multi-dimensional sensors, then the signal processor can generate a measurement signal (e.g., temperature) based at least in part on a resonant frequency shift (e.g., a mode shift) and generate an acoustic measurement signal based at least in part on an oscillation of optical power.

[0037] A wavelength division multiplexer 24 is coupled to the plurality of optical sensors S1, S2, S3, and S4 to multiplex the plurality of output optical signals into a single output channel. It should be understood that any suitable type of optical fiber, waveguide, or the like can be used to couple the wavelength division multiplexer 24 to the array of sensors S1, S2, S3, and S4. The optical output port 18 is coupled to the wavelength division multiplexer 24 for outputting the plurality of output optical signals in a single output channel via a single optical fiber 28. This optical fiber can then be coupled to one or more signal processing units 20 for performing any necessary signal processing depending on the specific type of sensors S1, S2, S3, and S4 and the specific application of the PIC chip 14. It should be understood that a single optical fiber 28 is shown for exemplary purposes only, and that any suitable type of optical waveguide can be used.

[0038] The use of the demultiplexer 22 and the multiplexer 24 allows for a reduction in the number of input ports 16 and output ports 18, respectively. Specifically, the number of input ports 16 and output ports 18 is reduced by the number of wavelength division multiplexer (WDM) channels w, where w represents the number of different wavelengths involved. In the above non-limiting example, w is 4. It should be understood that any suitable type of multiplexing / demultiplexing device can be used. Non-limiting examples of such devices suitable for integration on a PIC chip include arrayed waveguide gratings (AWGs), echelle gratings, Mach-Zehnder interferometers (MZIs), and reverse-engineered wavelength (de)multiplexers. Due to the requirement to pair with dense arrays of sensing units, a multiplexing / demultiplexing device with a compact footprint is preferred. Specifically, the profile of the demultiplexer 22 and / or multiplexer 24 should be compact, at least in the lateral dimension of the sensor array requiring a small pitch. The size of the profile of the demultiplexer 22 and / or multiplexer 24 in the lateral dimension should be maintained at least at the pitch × w. It will be appreciated that the input port 16 and the output port 18 may be any suitable type of optical coupler.As a non-limiting example, the input port 16 and the output port 18 may be, or include, a spot size converter (SSC).

[0039] As discussed above, it will be appreciated that the optical circuitry does not necessarily have to include a PIC chip. As a non-limiting example, Figure 7 As shown, the optical circuit 10 ′ is substantially the same as the optical circuit 10 , however, the PIC chip 14 has been removed, and the demultiplexer 22 , the multiplexer 24 and the plurality of optical sensors S1 , S2 , S3 , S4 may be mounted on any suitable structure or housing, or may be incorporated into any associated device (including those for acoustic sensing and / or for multi-dimensional signal detection).

[0040] As a further non-limiting example, multiple optical sensors and acoustic generators may be housed together in a probe. Figure 8A and Figure 8B In a non-limiting example, multiple optical sensors and acoustic generators are housed together in a hybrid sensor transducer probe 600. The hybrid sensor transducer probe 600 may be adapted for external use. As a further non-limiting example, multiple optical sensors may be provided in the form of optical acoustic transducers 602, and the acoustic transducer may be an acoustic energy generator (AEG) based transducer 604. For ease of discussion, these two components are described in detail in the accompanying drawings. Figure 8A and Figure 8B It will be appreciated that the features of these two components may be mixed and intermixed where functionality requires, as discussed in more detail below.

[0041] As a non-limiting example, Figure 8AThe photoacoustic transducer 602 illustrated in FIG may include an optical sensor array 606 comprising one or more optical sensors contained within a probe head 608 of a hybrid sensor transducer probe 600. The photoacoustic transducer 602 may also include an optical waveguide 610 (e.g., a fiber optic cable) disposed within a handle 612 of the hybrid sensor transducer. Figure 8B The AEG-based transducer 604 shown in FIG may include an AEG transducer stack 614 that includes one or more AEG transducers and the components necessary for their operation contained within the probe head 608 of the hybrid sensor transducer 600. The AEG-based transducer 604 may also include circuitry 616 (such as a flexible circuit, etc.), interconnects 618, and a connecting cable 620 (e.g., a coaxial cable, etc.). These may be disposed within the handle 612 of the hybrid sensor transducer 600 and / or within the probe head 608, as desired. The hybrid sensor transducer 600 may also include a hybrid cable 622 that is configured to carry both the optical waveguide 610 and the connecting cable 620 back to the system.

[0042] The optical sensor array 606 may include a bundle of fiber optic sensors, or in another non-limiting example, the optical sensor array 606 may include an on-chip optical sensor array. Furthermore, the demultiplexer 22, the multiplexer 24, and any suitable ports, couplings, or other types of connectors, interconnects, etc., may also be housed within the handle 612. It should be understood that the overall configuration, shape, and relative dimensions of the hybrid sensor transducer probe 600 are shown for exemplary purposes only and may vary. Furthermore, it should be understood that at least a portion of the hybrid sensor transducer probe 600 may be incorporated into other structures or devices. As a non-limiting example, the handle 612 may include, be attached to, be incorporated with, or be incorporated through a catheter or similar structure.

[0043] exist Figure 2In an alternative embodiment, optical sensor circuit 100 includes multiple optical input ports 106 on PIC chip 114. Multiple optical input ports 106 are provided for receiving multiple input channels, respectively, via multiple optical fibers 126. As a non-limiting example, four lasers 102 can be used to generate optical signals having unique wavelengths λ1, λ2, λ3, and λ4. A bundle of four optical fibers 126 couples laser units 102 to input ports 106 of PIC chip 114. Each individual optical fiber carries four optical signals having wavelengths λ1, λ2, λ3, and λ4. Thus, there are 16 different optical signals across the four channels, four signals per channel in this non-limiting example. It should be understood that optical fibers 126 are shown for exemplary purposes only, and any suitable type of optical waveguide may be used. Further, as discussed above, it should be understood that the optical circuit may be integrated into or include a PIC chip, etc., or alternatively, it may form or be part of any other suitable type of optical circuit or optical sensor system.

[0044] In this non-limiting example, the PIC chip 114 can optionally be provided with a power splitter 104 that communicates with the plurality of optical input ports 106 for splitting each input channel into a plurality of sub-channels carrying a plurality of input optical sub-signals. It should be understood that any suitable type of optical power splitter can be used. Non-limiting examples of power splitters that can be used include Y-branch optical waveguides and multi-mode interferometers. Continuing with the non-limiting example discussed above, if the power splitter 104 is a 1×8 splitter (i.e., splitting each optical signal into eight optical sub-signals, each having a fraction of the power of the original signal), the power splitter 104 will generate 128 separate optical sub-signals; i.e., 16 optical signals are split 8 times, resulting in 128 sub-signals. It should be understood that any suitable type of optical fiber, waveguide, etc. can be used to connect the power splitter 104 to the plurality of input ports 106. The power divider 104 may divide the total power / intensity of each optical signal equally; ie, in the example discussed above, each of the eight optical sub-signals may have 1 / 8 the power / intensity of the original optical signal.

[0045] A wavelength division multiplexer 122 is coupled to the power divider 104 to demultiplex each of the plurality of input optical sub-signals, and a plurality of optical sensors are coupled to the wavelength division multiplexer 122 to receive the plurality of input optical sub-signals and output a corresponding plurality of output optical signals. Following the non-limiting example discussed above, the wavelength division multiplexer 122 separates 128 optical sub-signals, each of which has a wavelength λ1, λ2, λ3, or λ4, and these individual optical sub-signals are input to optical sensors S1, S2, S3, S4, ..., S128, respectively, which are also included on the PIC chip 114. It should be understood that the sensors S1, S2, S3, S4, ..., S128 can be any suitable type of optical sensor, such as, but not limited to, a photoacoustic sensor. Further, it should be understood that any suitable type of optical fiber, waveguide, etc. may be used to couple the wavelength division multiplexer 122 with the array of sensors S1 , S2, S3, S4, ..., S128.

[0046] The output of each sensor S1, S2, S3, S4, ..., S128 generally has the same wavelength as the input sub-signal; that is, in this non-limiting example, the optical signal output from the array of sensors S1, S2, S3, S4, ..., S128 will generally have a wavelength λ1, λ2, λ3, or λ4 that matches the wavelength of the corresponding input optical sub-signal. A wavelength division multiplexer 124 is coupled to the plurality of optical sensors S1, S2, S3, S4, ..., S128 to multiplex the plurality of output optical signals into a plurality of output channels. Each output channel contains an optical signal having the same wavelength as that contained in each input channel; that is, continuing with this non-limiting example, the wavelength division multiplexer 124 receives 128 output optical signals from the optical sensors S1, S2, S3, S4, ..., S128 and outputs 32 optical channels, where each channel contains four signals having a corresponding wavelength λ1, λ2, λ3, or λ4. The plurality of optical output ports 108 on the PIC chip 114 are coupled to a wavelength division multiplexer 124 for outputting a plurality of output optical signals in a plurality of output channels. Typically, the total number of the plurality of optical output ports 108 (equal to the total number of output channels) is equal to the total number of output optical signals divided by the total number of input channels. Thus, in this non-limiting example, 32 output ports 108 are provided for coupling the PIC chip 114 to the signal processing unit 110 via 32 optical fibers 128.

[0047] It should be understood that the optical fiber 128 is shown for exemplary purposes only and that any suitable type of optical waveguide may be used. It should also be understood that the input port 126 and the output port 128 may be any suitable type of optical coupler. As a non-limiting example, the input port 126 and the output port 128 may be or include a spot size converter (SSC). It should further be understood that Figure 2 The four input optical sub-signals and four output optical signals shown in are for simplicity and illustration purposes only, and each of the sensors S1, S2, S3, S4, ..., S128 will have an input optical sub-signal from the wavelength division multiplexer 122 and a corresponding number of output optical signals.

[0048] While in alternative circuit 100, the wavelength division multiplexer 22 / 122, wavelength division multiplexer 24 / 124, and power splitter 104 may all be integrated within the same photonic integrated circuit (PIC) chip 14 / 114 as the optical sensor, it should be understood that one or more of these components may be located on a separate optical mid-level chip. Thus, rather than directly connecting the input and output waveguides to the PIC chip via input and output optical ports, the input and output waveguides are connected to a mid-level chip, which in turn connects to the input and output ports on the PIC chip 14 / 114. In practice, the materials and manufacturing processes of a PIC chip do not have a wide range of variability, as the specific sensing elements integrated on a PIC chip typically require very specific materials with very specific device parameters. By moving the demultiplexer 22 / 122, multiplexer 24 / 124, and / or power splitter 104 to a separate mid-level chip, the choice of materials and manufacturing processes is greatly expanded, as the specific requirements of the sensing elements do not apply to the mid-level chip.

[0049] Consider an example where only power divider 104 is moved to a separate mid-level chip connected to the PIC chip. Materials with higher power damage thresholds (e.g., silicon nitride) can be used to fabricate the mid-level chip, while silicon would still be used to fabricate the PIC chip. In this example, the ability to use silicon nitride in the mid-level chip addresses the power budget issue for power distribution. It should be understood that silicon and silicon nitride are non-limiting examples discussed for illustrative purposes only. Overall, the division of components between the PIC chip and the additional mid-level chip enables greater diversity in structure, configuration, and design, particularly within the mid-level chip, thereby optimizing interconnect efficiency. As a non-limiting example, the addition of the mid-level chip allows for the use of specific suspended high-power damage threshold materials, such as silicon nitride discussed in the above example. As another non-limiting example, multi-layer connectors can be incorporated into the mid-level chip. Both of these non-limiting examples may impact overall yield and / or be incompatible with sensor chip design and manufacturing processes, increasing wafer costs, making their use in the PIC chip impractical or infeasible. However, by adding the mid-level chip, these materials and designs can be used without disrupting the primary sensor PIC chip.

[0050] Regarding the present optical sensor circuits 10 and 100, it should be noted that WDM branching increases the power budget; that is, the shared input waveguide needs to handle the power of p×w channels, where p is the power split ratio and w is the number of WDM channels. By moving the power splitter 104 to the mid-level chip, a higher power split ratio can be achieved. It should be noted that while the number of input ports 16 / 106 on the PIC chip 14 / 114 increases if the power splitter 104 is moved to the mid-level chip, the total width of the input ports 16 / 106 (and therefore the width of the PIC chip 14 / 114) can be maintained or even reduced because the spacing of the connectors on the mid-level chip is not limited by the fiber diameter. Furthermore, the manufacturing flexibility of the mid-level chip allows for specialized chip connectors, which can improve the connection efficiency to the optical fiber and sensor chip. Thus, even though the mid-level chip introduces more connection interfaces, lower insertion loss of the optical I / O can be achieved.

[0051] It will be appreciated that, similar to the previous embodiments, the optical sensor may be provided as an optical sensor array incorporated into a hybrid sensor transducer probe, such as in Figure 8A and Figure 8B Similarly, the demultiplexer 122, the multiplexer 124, the power splitter 104, and any suitable ports, couplings, or other types of connections, interconnects, etc., may also be received within the handle 612 or similar structure or device of the hybrid sensor transducer probe 600.

[0052] Usually, such as Figure 3As shown, the photoacoustic sensor system 200 operates by pumping optical signals of fixed wavelengths into on-chip sensing units contained in a photonic integrated circuit (PIC) chip 204. One or more optical signals are typically generated by one or more laser units 202, such that each signal has a known and constant wavelength. Within the chip 204, the optical signals respond to acoustic / ultrasound pressure scattered from the imaging object or patient. The output optical signals from the sensor array on the PIC chip 204 are then transmitted from the chip 204 to a signal processing unit 210 for use, for example, in biomedical imaging, to generate or provide information or data related to the sensed physical parameter. In the photoacoustic sensor system, the optical signals generated by the laser units 202 passing through the sensor array are modified by the acoustic / ultrasound pressure waves, causing the output optical signals to be changed by the modification. These changes (e.g., in phase) allow the system to derive information about the target. In multidimensional sensing, a measurement signal indicative of the corresponding physical parameter is generated from the modified optical signals.

[0053] The sensitivity of the system 200 is closely related to the amount of light available in the on-chip sensing unit. Although sensing performance generally benefits from higher light intensity (i.e., optical power) per channel, many different designs and optimization schemes have been used to maximize the efficiency of the sensing unit. The output power of the laser unit 202 is limited by commercial availability and is typically provided in the range of 1 mW to 200 mW, which is high enough to support multiple well-designed sensing units. The number of sensing units that can be optically powered by one laser unit can be defined by the power split ratio p. In practice, the optical signal is transmitted to the sensor unit via an on-chip optical I / O interface consisting of one or more optical input ports 206 and one or more optical output ports 208. The interface connects light from an input optical waveguide (which can be, for example, an optical fiber on the laser side) to an on-chip waveguide on the sensing unit side.

[0054] After the light is transmitted onto the sensor chip 204, the optical signal can be evenly divided into multiple channels before being fed to the individual sensing units. As will be described in more detail below, this power distribution is performed to allow the use of high-output power laser units, which in turn minimizes the total number of expensive laser units 202 required. After photoacoustic sensing, the output optical signal is transferred to an off-chip analysis unit via one or more optical output ports 208. This output interface connects the light from the waveguide on the sensing unit side to the output optical waveguide (e.g., optical fiber) on the analysis unit side.

[0055] Conventionally, each optical signal from a sensing unit is transmitted to its corresponding signal analysis unit 210 via its separate optical I / O interface. If the imaging probe comprises, for example, N sensor units, a total of N / p input optical waveguides and input ports are required, and N output optical waveguides (i.e., each channel) are required. Optical ports). For example, if chip 204 contains an array of 128 individual sensors, 128 output fibers are required. All input fibers and output fibers are connected to input port 106 and output port 108, respectively. For an imaging configuration with 128 sensing units, 144 total optical ports and fibers are required. This is based on a sensor chip that splits the optical input signal into 8 channels (due to sensor requirements), thus requiring 16 optical input ports and 128 optical output ports, for a total of 144 ports.

[0056] As imaging resolution and field of view increase, the number of input / output optical waveguides and on-chip optical I / O ports increases along with the number of sensing elements. For example, manufacturing a single imaging probe that interfaces with 100 optical fibers is both difficult and expensive. The difficulty is largely due to the optical alignment required at the optical I / O interface to ensure that all optical fibers are precisely aligned and permanently fixed to their corresponding on-chip optical ports. Due to the large number of optical fibers, the raw material costs are large, and the operating costs for manufacturing such a chip are even greater. In addition to the above, as a practical example, the alignment of the fiber edge connectors on the PIC chip requires micron-level precision, as the mode profile diameter of conventional optical fibers is only 10μm. Therefore, for more than 100 optical channels with a pitch of approximately 0.127mm, the width of the fiber array unit must be greater than 10mm, requiring an angular tolerance of approximately 1 / 10000 rad. In practice, the inevitable bending of the fiber array unit may even make such attachment impossible. Therefore, it is very important for the optical sensing industry to be able to significantly reduce the number of optical fibers and on-chip I / O ports so that the on-chip sensing array can be scaled for higher resolution and wider field of view.

[0057] Furthermore, the imaging resolution and field of view requirements can generate criteria for the form factor of the imaging probe. A common standard is the pitch of the linear sensor array, which is typically in the range of 0.1 mm to 0.3 mm. Typical optical fibers have a diameter of 0.125 mm. Therefore, reducing the number of optical ports per channel is important to avoid significant changes in the form factor of the probe head due to the space requirements for the optical I / O.

[0058] As discussed above, one approach to reducing the number of optical fibers and on-chip I / O ports is optical power branching; that is, a single optical signal is split or distributed into multiple signals, each with a fraction of the original power, thereby reducing the number of input optical ports. After the light is transmitted onto the sensor chip, the optical signal undergoes 1-p power distribution before being fed to the individual sensor units. For a fixed-wavelength light source, the laser power can be increased so that only one input fiber and on-chip input port are required to support the total optical power requirements of all on-chip sensing elements. As an example, for a chip with 1×8 optical power branching (i.e., one signal is split into eight signals with 1 / 8 the original power), a single laser source with a fixed wavelength can support eight sensing elements via one on-chip input port and a single optical splitter. While the benefits of this theoretical scenario are clear, this approach is impractical due to the limited accessibility and safety issues of the required high-power laser source, as well as the power budget of the on-chip ports and waveguides before power distribution. Furthermore, this technology still requires a large number of optical fibers and on-chip I / O ports to transmit the output signal. It would therefore be clearly desirable to be able to utilize an alternative, more efficient form of distribution, whether used alone or in combination with power distribution. However, as discussed above, it will be appreciated that the optical circuitry may be integrated into or include a PIC chip or the like, or alternatively, may form or be part of any other suitable type of optical circuitry or optical sensor system.

[0059] It should be understood that the optical sensor circuits 10, 100 can be incorporated into any suitable type of sensor system. As non-limiting examples, the sensor system can include a fiber optic sensor array or hybrid sensor transducer that can be incorporated into an ex vivo or in vivo device, such as for imaging, diagnostic procedures, therapeutic procedures, multi-dimensional sensing, object visualization or tracking, ultrasound, interactive ultrasound, intracavitary ultrasound (EUS), endobronchial ultrasound (EBUS), or intravascular ultrasound (IVUS). As non-limiting examples, the optical sensor can be any of the optical sensors described in the following co-pending applications, or optical sensors similar to those described in the following co-pending applications: U.S. patent application Ser. No. 17 / 832,507, entitled “Whispering Gallery Mode Resonators for Sensing Applications”; U.S. patent application Ser. No. 17 / 956,640, entitled “Optical Microresonator Array Device”; and International Patent Application Ser. No. PCT / US 2022 / 04125, entitled “Multi-dimensional Signal Detection with Optical Sensor,” each of which is incorporated herein by reference in its entirety. The ex vivo or in vivo device can be one of or similar to any hybrid array described in the following co-pending applications: U.S. patent application Ser. No. 17 / 990,596, entitled “Mixed Ultrasound Transducer Arrays”; U.S. patent application Ser. No. 17 / 244,605, entitled “Modularized Acoustic Probe”; and International Patent Application No. PCT / US2022 / 077762, filed on October 7, 2012, entitled “Ultrasonic Beacon Visualization with Optical Sensors,” each of which is incorporated herein by reference in its entirety.

[0060] As a non-limiting example, Figure 4An optical sensor system 300 is illustrated for use with an optical sensor adapted and / or configured to detect acoustic signals. The optical sensor system 300 includes a light source 302 (such as a laser), a light receiving device 304 (such as a photodetector), one or more optical waveguides 306, and an optical sensor 308, which may be or incorporate the optical sensor circuit 10 and / or 100. In operation, the light source 302 provides an initial optical signal 310 to the optical sensor 308 via the optical waveguide 306. The provided initial optical signal 310 is returned by the optical sensor 308 along the optical waveguide 306. The returned optical signal 312 propagates through the optical waveguide 306 and is received at the light receiving device 304. As discussed above, an acoustic signal (such as an ultrasound (US) signal) incident on the optical sensor 308 changes the optical properties of the optical sensor 308 (which may include physical structure and optical material properties). This change in optical properties can be measured based on changes in the returned optical signal 312.

[0061] exist Figure 5 In a further embodiment, a photoacoustic sensor system 400 is provided. It should be understood that the photoacoustic sensor system 400 may include any suitable type of hardware and components to facilitate the use of an ultrasonic transducer and / or an ultrasonic probe. The photoacoustic sensor system 400 may include a processing system 402, an optical subsystem 404, and a transducer probe 406 including an optical sensor 408 and an AEG transducer 410. The optical sensor 408 may be any suitable type of optical sensor, such as, but not limited to, a photoacoustic sensor. The photoacoustic sensor system 400 includes components, devices, hardware, and software that facilitate the use of the optical sensor 408. The optical sensor 408 may include a fiber optic sensor array, a photonic integrated sensor array, or any other suitable sensor arrangement. The AEG transducer 410 may be configured to generate and receive acoustic signals or simply generate acoustic signals.

[0062] The processing system 402 may include a processing unit (PU) 414 and an image reconstruction unit (IRU) 416. The processing unit 414 may include at least one computer processor, at least one non-transitory computer-readable storage medium, and appropriate software instructions. The processing unit 414 is configured to provide control signals to and receive information signals from a light source control unit (LSCU) 418, a light receiving device (LRD) 420, and an acoustic control unit (ACU) 422. The processing unit 414 may communicate with the light source control unit 418 (via control signals and information signals) to thereby control the optical signals provided to the optical sensor 408. The processing unit 414 may communicate with the acoustic control unit (ACU) 422 (via control signals and information signals) to thereby control and receive acoustic signals via the acoustic probe 406. The processing unit 414 is further configured to communicate with the light receiving device 420 to receive information signals associated with the optical signals received by the light receiving device 420. Thus, the processing unit 414 operates to provide necessary control signals in the photoacoustic sensor system 400 and receive acquired information signals.

[0063] Processing unit 414 further communicates with image reconstruction unit 416, which is configured to generate images based on the data and / or information acquired by processing unit 414. Image reconstruction unit 416 may generate images based on data related to a medium (such as a human body) captured by optical sensor 408 and AEG probe 410. Image reconstruction unit 416 may be integrated within a system including processing unit 414 and / or may be a separate system including at least one computer processor, at least one non-transitory computer-readable storage medium, and appropriate software instructions. Processing system 402 may provide control signals to output device 412 to provide data output. Output device 412 may include, for example, a display or a device including a display. In some variations, system 400 may also include a set of auxiliary interface devices (not shown) for inputting information into or outputting information from system 400. Such auxiliary devices may include, for example, a keyboard, mouse, monitor, webcam, microphone, touchscreen, printer, scanner, virtual reality (VR) head-mounted display, joystick, biometric reader, etc. (not shown). In some variations, the display may comprise an interactive user interface (e.g., a touch screen) and be configured to transmit a set of commands (e.g., pause, resume, and / or the like) to the light source 424. Additionally, in some variations, the system 400 may comprise or be communicatively coupled to one or more storage devices (e.g., local or remote memory devices).

[0064] In some embodiments, when one or more of the optical sensors can be used for multi-dimensional sensing to detect multiple physical signals (such as temperature and pressure) (e.g., detecting multiple different physical signals substantially simultaneously in real time or near real time), the processing device 402 may alternatively or further include additional systems. Measurement signals indicative of the physical signals (e.g., temperature information and pressure information) can be determined and then transmitted to, for example, a display or another output device 412 for real-time monitoring or other data related to the measurement area.

[0065] The optical subsystem 404 includes a light source control unit 418, a light source 424, optical devices (ODs) 426A, 426B, 426C, and a light receiving device 420. The light source control unit 418 is configured to interface with and control the light source 424 to control the generation of an initial optical signal 428. The light source 424 can generate continuous wave (CW) or pulsed light emission (stimulated emission, spontaneous emission, etc.). The initial optical signal 428 can include coherent light, such as laser light, provided in one or more modes and at one or more frequencies. The initial optical signal 428 can be a single frequency / wavelength, a selection of frequencies / wavelengths, and / or a broadband light source. Thus, the light source 424 can include a laser array configured to generate laser light in one or more modes and at one or more frequencies. In addition, depending on the application requirements, the polarization of the provided light can be controlled to optimize the detected signal level. The polarization state of the light can be controlled to be linearly polarized or circularly polarized at a certain angle. Linearly polarized light will respond optimally to a certain input ultrasound direction, while circularly polarized light will respond to ultrasound from all directions. The polarization of light can be defined from the laser source output, and the output polarization state can be controlled by an inline fiber polarizer, a paddle-type fiber polarization controller, an inline fiber polarization controller, or other types of polarization controllers.

[0066] Optical devices 426A, 426B, and 426C may be configured to manipulate or influence an initial optical signal 428 received at optical sensor 408. Initial optical signal 428 may be provided at multiple wavelengths or across a spectrum of wavelengths. Optical device 426A may include, for example, a wavelength division multiplexing (WDM) device configured to multiplex multiple frequencies of initial optical signal 428 provided by light source 424 for simultaneous transmission on optical waveguide 430, which guides initial optical signal 428 to optical sensor 408. The light source transmits the initial optical signal, which has passed through wavelength division multiplexing (WDM) device 426A, to optical device 426B. Optical device 426B may include a WDM device configured to demultiplex the initial optical signal 428 provided to optical sensor 408 and subsequently output light of different wavelengths. Thus, optical device 426B may be similar to wavelength division multiplexer 22 / 122 of the previous embodiment. Optical device 426B is in optical communication with optical device 426A and is used to separate the initial optical signal into optical signals, each optical signal having a wavelength associated therewith, and to combine the returned optical signals from the optical sensors, which are then directed through optical device 426C, which may include a WDM device (similar to the WDM 24 / 124 of the aforementioned embodiment), to optical receiving device 420.

[0067] The initial optical signal 428 is received by the optical sensor 408 and returned through one or more optical waveguides 430 to the optical device 426B, which can be further configured to multiplex the returned optical signal 432 (if necessary) for transmission to the optical receiving device 420. The returned optical signal 432 can be directed by the optical device 426B through and toward the optical device 426C, which can be a WDM device configured to demultiplex the returned optical signal 432 for receipt by the optical receiving device 420. The optical receiving device 420, which can be, for example, a photodetector array, can be in optical communication with the optical device 426C for receiving the respective wavelength components of the returned optical signal, such that phase shifts or other changes detected in the respective wavelength components are indicative of the sensed acoustic signal.

[0068] It will be appreciated that in embodiments where frequency multiplexing / demultiplexing of the initial optical signal 428 and the returned optical signal 432 is not required, optical devices 426A and 426B may not be required. The optical receiving device 420 may include any suitable device configured to detect incident light, including, for example, a photodetector. The optical receiving device 420 may also include, but is not limited to, a photodiode. The optical receiving device 420 may be in optical communication with an optical device 426C (e.g., a wavelength division multiplexing (WDM) splitter) for receiving individual wavelength components of the returned optical signal 432, such that detected phase shifts, polarization changes, or other changes in these individual wavelength components indicate sensed acoustic signals. Changes in the returned optical signal 432 may be converted (e.g., by the processing unit 414 and / or by additional optical components (such as a polarization-sensitive coupler and / or a frequency shifter)) into data representing the sensed acoustic signal (which data may be further used, for example, to generate data representing the tissue / anatomical structure of the medium being sonicated or the physical signal being measured).

[0069] In an embodiment, the initial optical signal 428 and the returned optical signal 432 signals may undergo pre-processing, beamforming, and post-processing as described in the following applications that disclose different methods for ultrasound beamforming and image processing, each of which is incorporated herein by reference: U.S. Patent Application No. 18 / 032,953, entitled “Image Compounding for Mixed Transducer Arrays”; U.S. Patent Application No. 18 / 025,081, entitled “Synthetic Aperture Imaging Systems and Methods Using Mixed Arrays”; U.S. Patent Application No. 18 / 901,073, entitled “Acousto-Optic Harmonic Imaging with Optical Sensors”; and U.S. Patent Application No. 18 / 901,073, entitled “Acoustic Imaging and Measurements Using Windowed Nonlinear Frequency Modulation Imaging”. Chirp (Acoustic Imaging and Measurement Using Windowen Nonlinear Modulation Frequency Modulation)”; International Patent Application No. PCT / US 2022 / 077762, entitled “Ultrasonic Beacon Visualization with Optical Sensors”; and International Patent Application No. PCT / US2022 / 041252, entitled “Multi-Dimensional Signal Detection with Optical Sensors.”

[0070] In some embodiments, the output device 412 may also include additional systems, such as medical procedures or diagnostic systems configured to use the output data. For example, the output device 412 may include an endoscopic system, a laparoscopic system, a robotic surgery system, a neurosurgery system, and may additionally include an interoperable ultrasound imaging system.

[0071] It will be understood that the examples provided are by way of example. Figure 5. A different configuration may be employed without departing from the scope of the present disclosure. For example, different arrangements of optical devices 426A, 426B, 426C and different numbers and arrangements of optical sensors 408 may be employed. In an embodiment, light source control unit 418 and acoustic control unit 422 may be incorporated into or integrated within processing system 402. Additional combinations of components of photoacoustic sensor system 400 may be selected as appropriate to achieve the functionality described herein.

[0072] Figure 6 A photoacoustic sensor system 500 is illustrated for use with a hybrid sensor array. The photoacoustic sensor system 500 includes components, devices, hardware, and software that facilitate the use of a hybrid sensor array 502. Certain aspects of the photoacoustic sensor system 500 are similar to Figure 5 Some aspects of the photoacoustic sensor system 400 are similar and thus are not repeated. The following describes the different aspects.

[0073] The photoacoustic sensor system includes a light source 504, which includes a single laser or several lasers operating at the same wavelength (e.g., to increase power). The initial optical signal from the light source 504 is split into multiple channels corresponding to the number of fiber optic sensors in an optical sensor array (OSA) 506. The initial optical signal passes through an optical circulator array (OCA) 508, which includes multiple circulators corresponding to the number of fiber optic sensors, where each signal is directed to a WDM unit from a WDM array 510.

[0074] The photoacoustic sensor system also includes a heating source 512, which includes a single laser or several lasers operating at the same wavelength (e.g., to increase power). As discussed herein, the heating source 512 operates at a frequency configured for thermal absorption by the fiber optic sensors of the optical sensor array 506. The initial thermal optical signal from the heating source 512 is split into a plurality of channels corresponding to the number of fiber optic sensors in the optical sensor array 506. The initial thermal optical signal passes through a thermal tuning unit 514, which operates to adjust the intensity of each thermal optical signal, thereby tuning the individual optical sensors of the optical sensor array 506. The thermal tuning unit can operate, for example, using an electrically variable optical attenuator. The resulting tuned thermal optical signal is provided to the WDM array 510 to be multiplexed with the corresponding initial optical signal and provided to the appropriate optical sensor of the optical sensor array 506. The thermal tuning unit (TTU) 514 is controlled by a thermal control unit (TCU) 516, which receives input from a light receiving device array (LRDA) 518. Input from the light receiving device array 518 is used in a feedback loop to individually control the heating (and therefore the thermal tuning characteristics) of each fiber optic sensor of the optical sensor array 506. The thermal tuning process is described above and can be used to tune the individual fiber optic sensors of the optical sensor array 506 to be sensitive to the same operating laser frequency.

[0075] Additional features of the photoacoustic sensor system 500 are similar to those of the photoacoustic sensor system 400. The returned optical signal is filtered from the thermal optical signal and passes through a circulator array 508 where it is directed to an array of photoreceivers 518. Alternatively, the photoreceiver array 518 can be selected to be relatively insensitive to the wavelength of the thermal optical signal, thereby allowing these signals to be received without unduly affecting the temperature of the photoreceiver array 518. The photoreceiver array 518 is configured to receive multiple returned optical signals (e.g., via individual photoreceivers of the array, each corresponding to one of the channels into which the initial optical signal was separated) and provide information and data thereof to a processing unit 520. The individual photoreceivers can be, for example, individual photodetectors.

[0076] The processing unit 520 further communicates with an AEG array 522 (for generating acoustic energy) via an acoustic control unit (ACU) 524. Information from the AEG array 522 and the optical sensor array 506 is used by the processing unit 520 to determine the acoustic environment (including, for example, imaging). Additionally, the processing unit 520 may receive output from the thermal tuning control unit 516 for interpreting the returned optical signal. The acoustically determined information may be output via an output device 525, which may be, for example, a display, another medical system, or the like. By splitting the optical signal from a single light source 504 into multiple channels, the photoacoustic sensor system 500 significantly reduces the number of lasers required for the light source 504. This can reduce the cost, size, and power consumption of the system 400.

[0077] It should be understood that the optical sensor circuits and optical sensing methods are not limited to the specific embodiments described above, but encompass any and all embodiments within the scope of the general language of the following claims enabled by the embodiments described herein or otherwise shown in the drawings or described above in terms sufficient to enable one of ordinary skill in the art to make and use the claimed subject matter.

Claims

1. An optical sensor circuit comprising: an optical input port for receiving a plurality of input optical signals in a single input channel, wherein each of the input optical signals has a unique wavelength associated therewith; a wavelength division multiplexer coupled to the optical input port to demultiplex the plurality of input optical signals; a plurality of optical sensors coupled to the wavelength division multiplexer for respectively receiving the plurality of input optical signals and outputting a corresponding plurality of output optical signals; a wavelength division multiplexer coupled to the plurality of optical sensors to multiplex the plurality of output optical signals into a single output channel; and An optical output port is coupled to the wavelength division multiplexer for outputting the plurality of output optical signals in the single output channel.

2. The optical sensor circuit according to claim 1, wherein: Each of the output optical signals has a unique wavelength associated therewith that matches the wavelength of a corresponding one of the input optical signals.

3. The optical sensor circuit according to claim 1, wherein: Each of the optical sensors comprises a photoacoustic sensor.

4. The optical sensor circuit according to claim 1, wherein: The plurality of optical sensors comprises an array of fiber optic sensors.

5. The optical sensor circuit of claim 1 , further comprising an acoustic transducer, wherein: The plurality of optical sensors and the acoustic transducer are mounted together in a hybrid sensor-transducer probe.

6. An optical sensor circuit comprising: a plurality of optical input ports, the plurality of optical input ports being configured to respectively receive a plurality of input channels, wherein each of the input channels carries a plurality of input optical signals, wherein each of the input optical signals within each of the input channels has a unique wavelength associated therewith; a power divider configured to divide each of the input channels into a plurality of sub-channels carrying a plurality of input optical sub-signals; a wavelength division multiplexer coupled to the power divider for demultiplexing each of the plurality of input optical sub-signals; a plurality of optical sensors coupled to the wavelength division multiplexer for respectively receiving the plurality of input optical sub-signals and outputting a corresponding plurality of output optical signals; a wavelength division multiplexer coupled to the plurality of optical sensors to multiplex the plurality of output optical signals into a plurality of output channels; and A plurality of optical output ports are coupled to the wavelength division multiplexer for outputting the plurality of output optical signals in the plurality of output channels.

7. The optical sensor circuit according to claim 6, wherein: Each of the output optical signals has a unique wavelength associated therewith that matches the wavelength of a corresponding one of the input optical sub-signals.

8. The optical sensor circuit according to claim 6, wherein: The total number of the plurality of output channels is equal to the total number of the output optical signals divided by the total number of the input channels.

9. The optical sensor circuit according to claim 6, wherein: Each of the optical sensors comprises a photoacoustic sensor.

10. The optical sensor circuit according to claim 6, wherein: The plurality of optical sensors comprises an array of fiber optic optical sensors.

11. The optical sensor circuit of claim 6, further comprising an acoustic transducer, wherein The optical sensor and the acoustic transducer are mounted together in a hybrid sensor-transducer probe.

12. An optical sensing method, comprising: receiving a plurality of input optical signals within a single input channel, wherein each of the input optical signals has a unique wavelength associated therewith; demultiplexing the plurality of input optical signals; inputting the demultiplexed plurality of input optical signals into a plurality of optical sensors respectively; and A plurality of output optical signals respectively outputted by the plurality of optical sensors are multiplexed into a single output channel.

13. The optical sensing method according to claim 12, wherein: Each of the output optical signals has a unique wavelength associated therewith that matches the wavelength of a corresponding one of the input optical signals.

14. An optical sensing method, comprising: receiving a plurality of input channels, wherein each of said input channels carries a plurality of input optical signals, wherein each of said input optical signals within each of said input channels has a unique wavelength associated therewith; Distributing the power of each input channel into a plurality of sub-channels carrying a plurality of input optical sub-signals; demultiplexing each input optical sub-signal of the plurality of input optical sub-signals; inputting the demultiplexed plurality of input optical sub-signals into a plurality of optical sensors respectively; and The plurality of output optical signals respectively outputted by the plurality of optical sensors are multiplexed into a plurality of output channels.

15. The optical sensing method according to claim 14, wherein: Each of the output optical signals has a unique wavelength associated therewith that matches the wavelength of a corresponding one of the input optical sub-signals.

16. The optical sensing method according to claim 14, wherein: The total number of the plurality of output channels is equal to the total number of the output optical signals divided by the total number of the input channels.

17. A photoacoustic sensor system comprising: an acoustic transducer for transmitting an acoustic signal to a sample to be sensed; a light source for generating a plurality of input optical signals, wherein each of the input optical signals has a unique wavelength associated therewith; a wavelength division multiplexer coupled to the optical source to demultiplex the plurality of input optical signals; a plurality of optical sensors, the plurality of optical sensors being configured to sense the sample, the plurality of optical sensors being coupled to the wavelength division multiplexer and configured to respectively receive the plurality of input optical signals and output a corresponding plurality of output optical signals; a wavelength division multiplexer coupled to the plurality of optical sensors to multiplex the plurality of output optical signals into a single output channel; and Means for processing the single output channel to produce an image of the sample.

18. The photoacoustic sensor system according to claim 17, wherein: Each of the output optical signals has a unique wavelength associated therewith that matches the wavelength of a corresponding one of the input optical signals.

19. The photoacoustic sensor system according to claim 17, wherein: Each of the optical sensors comprises a photoacoustic sensor.

20. The photoacoustic sensor system according to claim 17, wherein The optical sensor includes a fiber optic sensor array.

21. The photoacoustic sensor system according to claim 17, wherein: The optical sensor and the acoustic transducer are mounted together in a hybrid sensor-transducer probe.

22. The photoacoustic sensor system of claim 20, further comprising a heating source for selectively heating individual ones of the optical sensors of the optical sensor array for tuning the individual ones of the optical sensors of the optical sensor array.

23. The photoacoustic sensor system of claim 17, further comprising means for processing the single output channel to produce data representative of multi-dimensional sensing.

24. An optical sensor circuit comprising: an optical input port for receiving a plurality of input optical signals in a single input channel, wherein each of the input optical signals has a unique wavelength associated therewith; a plurality of optical sensors, the plurality of optical sensors being configured to respectively receive the plurality of input optical signals and output a plurality of output optical signals; a wavelength division multiplexer for receiving individual wavelength components of the plurality of output optical signals; an optical output port coupled to the wavelength division multiplexer for outputting the plurality of output optical signals in the single output channel; and Means for processing the single output channel to produce data representative of the sensed physical parameter.

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