We propose a simple and flexible multiwavelength Raman fiber laser based on phase-shifted fiber Bragg gratings (FBGs) and a tunable chirped FBG. Using a simple multiwavelength Raman laser configuration with a single phase-shifted FBG and a tunable chirped FBG, we readily achieved simultaneous two-channel sensing probes with a high extinction ratio of more than 50 dB over a 50-km distance. The multiwavelength output was stable and the peak fluctuation was less than 0.5 dB. The temperature and strain sensitivities are estimated to be 10.1 pm/degrees C and 7.5 pm/microstrain, respectively.
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http://dx.doi.org/10.1364/ol.30.001114 | DOI Listing |
Neurophotonics
October 2024
Technical University of Denmark, DTU Electro, Lyngby, Denmark.
Significance: Extending the photoacoustic microscopy (PAM) into the mid-infrared (MIR) molecular fingerprint region constitutes a promising route toward label-free imaging of biological molecular structures. Realizing this objective requires a high-energy nanosecond MIR laser source. However, existing MIR laser technologies are limited to either low pulse energy or free-space structure that is sensitive to environmental conditions.
View Article and Find Full Text PDFHerein, we report on two-dimensional (2D) suprawavelength crystalline ZnO microstructures induced by a single ultraviolet (UV) femtosecond laser beam (400 nm, 35 fs, 666 Hz) with significant absorption enhancement. The achieved absorption values of 90-99% and 75-80% in the UV and visible spectral regions, respectively, were approximately 1.16 and 12 times higher than those of the blank ZnO crystal.
View Article and Find Full Text PDFACS Sens
November 2024
State Key Laboratory of Systems Medicine for Cancer, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030, P. R. China.
Label-free surface-enhanced Raman spectroscopy (SERS) is capable of capturing rich compositional information from complex biosamples by providing vibrational spectra that are crucial for biosample identification. However, increasing complexity and subtle variations in biological media can diminish the discrimination accuracy of traditional SERS excited by a single laser wavelength. Herein, we introduce a multiwavelength SERS approach combined with machine learning (ML)-based classification to improve the discrimination accuracy of human urine specimens for bladder cancer (BCa) diagnosis.
View Article and Find Full Text PDFWe report on multi-wavelength generation through simultaneous second-order and third-order nonlinear parametric processes following cascaded stimulated Raman scattering (SRS) in silica fibers. The fiber system consists of a short standard step-index silica fiber and a microfiber tapered from it. When this system is pumped with a 130 ps laser at 1040 nm, multiple new wavelengths in the UV (340-370 nm) and green (507-547 nm) bands arise through four-wave mixing (FWM)/sum-frequency generation (SFG) from the pump and its Raman signals.
View Article and Find Full Text PDFFor the first time to our knowledge, multiwavelength, highly transient, single-pass stimulated Raman scattering with a low wavelength spacing on dual (stretching and bending) Raman modes in Sr(MoO)(WO) and Sr(MoO)(WO) solid solutions in a range of 1000-1300 nm (transparence window of biological tissue) under ultrafast chirped pulse laser pumping is comparatively investigated in the interests of multicolor two-photon imaging of a living tissue. For both the solid solutions, the optimum range (1-5 ps) of chirped pump pulse durations for multiwavelength Raman conversion on dual Raman modes was wider than for SrMoO (2-3 ps) due to the higher integral cross section of the bending Raman mode. Higher efficient SRS conversion took place at negative chirping of the pump pulse with its stretching from 0.
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