Time-Resolved Raman Spectrometer With High Fluorescence Rejection Based on a CMOS SPAD Line Sensor and a 573-nm Pulsed Laser

A time-resolved Raman spectrometer is demonstrated based on a 256 × 8 single-photon avalanche diodes fabricated in CMOS technology (CMOS SPAD) line sensor and 573-nm fiber-coupled diamond laser delivering pulses with duration below 100-ps full-width at half-maximum (FWHM). The collected backscattered light from the sample dispersed using custom volume holographic grating having 1800 lines/mm. Efficient fluorescence rejection measurements achieved due to combination of time gating sub-100-ps scale excitation wavelength. To demonstrate performance spectrometer, fluorescent oil samples were measured. For organic sesame seed continuous wave (CW) mode fluorescence-to-Raman ratio 10.5 lifetime 2.7 ns, signal-to-distortion value 76.2 was achieved. roasted CW 82 2.2 28.2 In both cases, reduced by factor 24-25 owing gating. oil, spectral distortion dominated dark counts, while for more main source timing skew sensor. With presented postprocessing techniques, level could be 88%-89% samples. Compared common 532-nm excitation, approximately 73% lower observed when analyzing oil.