Hybrid optical parametrically-oscillating emitter
Inventors
Wong, Kenneth Kin Yip • SHI, Jiawei • Li, Mingsheng • KANG, Jiqiang
Assignees
Advanced Biomedical Instrumentation Centre Ltd • Versitech Ltd
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Publication Number
US-12461020-B2
Publication Date
2025-11-04
Expiration Date
Abstract
An optical-resolution photoacoustic microscopy (OR-PAM) system for visualizing water content deep in biological tissue uses an all-fiber 1930-nm hybrid optical parametrically-oscillating emitter. The emitter includes a tunable laser source whose output is amplified by a first erbium-doped fiber amplifier (EDFA). The output of the first amplifier is modulated with a Mach-Zehnder amplitude modulator that receives an RF signal with a nanosecond pulse width and a multiple kilohertz repetition rate. A second EDFA further amplifies the signal and passes it to a fiber circulator that in turn delivers it to a 1950/1550 mm fiber wavelength-division-multiplexing coupler WDM. The coupler introduces the signal to a cavity that includes a spool of highly nonlinear fiber and a Thulium-doped fiber amplifier TDFA. From the TDFA the signal reaches a 50/50 fiber coupler that sends part to a second output TDFA and guides part back to the cavity through a port of the WDM.
Core Innovation
The invention provides an optical-resolution photoacoustic microscopy (OR-PAM) system for visualizing water content in the deep tissue of biological organisms. The system uses an all-fiber hybrid optical parametrically-oscillating emitter as an input, and the emitter operates in a range from 1877 nm to 1980 nm. The hybrid structure uses nonlinear fibers with stable phase matching and rare-earth fibers, so the emitter supports water-content visualization in deep tissue.
The emitter architecture is described as a hybrid optical parametrically-oscillating emitter that employs nonlinear fibers with stable phase matching together with rare-earth fibers. The emitter includes an optical parametrically-oscillating structure that generates an idler within a wavelength range, and the design is tied to polarization control and four-wave mixing for parametric conversion in a cavity. The emitter structure is configured so that the output supports OR-PAM operation in the targeted wavelength region for water-content imaging.
The documented system further integrates fiber-laser components and a cavity-based parametric-gain process. It amplifies laser output using erbium-doped fiber amplifiers, applies RF-driven Mach-Zehnder amplitude modulation to produce a rectangular pulse train, and uses polarization control for polarization-controlled four-wave mixing in a cavity containing highly nonlinear fiber with stable phase-matching. The design additionally includes thulium-doped fiber amplification and extra pumping at 1650 nm to enhance the idler power and address residual pump, enabling deep-tissue water visualization with the OR-PAM system.
Claims Coverage
The document includes one independent claim. It specifies an OR-PAM system for visualizing water content in deep tissue using an all-fiber hybrid optical parametrically-oscillating emitter operating between 1877 nm and 1980 nm, with nonlinear fibers with stable phase matching and rare-earth fibers, while dependent claims refine emitter and imaging/detection configurations.
All-fiber hybrid optical parametrically-oscillating emitter for deep-tissue water visualization
An optical-resolution photoacoustic microscopy (OR-PAM) system for visualizing water content in the deep tissue of biological organisms, comprising as an input an all-fiber hybrid optical parametrically-oscillating emitter operating in a range from 1877 nm to 1980 nm, wherein the hybrid structure uses nonlinear fibers with stable phase matching and rare-earth fibers.
Overall claim coverage centers on an OR-PAM system that visualizes deep-tissue water content using an all-fiber hybrid optical parametrically-oscillating emitter in 1877–1980 nm, with nonlinear fibers having stable phase matching combined with rare-earth fibers; dependent claims further refine emitter construction and aspects of photoacoustic acquisition and display.
Stated Advantages
Strong water absorption at 1930 nm for improved water-lipid contrast.
Reduced lipid artifact signals.
Expected SNR of about 19 dB.
Penetration depth of about 2.4 mm.
Documented Applications
Phantom and in-vitro experiments comparing 1930-nm water imaging versus 1750-nm lipid imaging in deep-tissue water visualization contexts, with reported supporting experiments using ultrasound gel/air bubbles and salmon fish belly.
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