Dual-Wavelength Raman Fusion Spectroscopy

Abstract

Spatially compressed dual-wavelength Raman spectroscopy allows recording the full Raman spectrum using a detection system with limited spectral range. The common approach is to record the spectra with the two excitation lasers consecutively and then concatenate the full spectrum. However, with this approach, quantitative analysis for process monitoring is not possible as the investigated object may change between the two acquisitions. In this Note, spectral fusion is proposed as a concept to overcome this problem. The sample is illuminated by the two lasers simultaneously, hence leading to an on-chip fusion of the different parts of the Raman spectrum. It is shown that the resulting data are suitable for quantitative evaluation using univariate and multivariate methods. Dual-wavelength Raman fusion spectroscopy offers new opportunities for building highly compact devices for analytical chemistry.

Single‐, Dual‐, Triple, and Quadruple‐Wavelength Surface‐Emitting Lasing in Blue‐Phase Liquid Crystal

“…Multicolor lasers show significant applications in the fields of wavelength division multiplexing communication, [ 1–5 ] highly sensitive optical sensors, [ 6–9 ] medical diagnosis, [ 10 ] laser displays, [ 11,12 ] and precise spectroscopy. [ 13,14 ] Up to now, dual‐wavelength [ 1,6–8,15 ] or dual‐color lasers [ 16–19 ] have been achieved in several resonators such as grating, [ 20–22 ] heterogeneous structures, [ 17,12,23 ] single crystals, [ 3,19,24 ] fibers, [ 2,5,9,25,26 ] metal–organic framework, [ 24,27 ] plasmon resonances, [ 28–30 ] colloidal photonic crystals (PCs), [ 31 ] and cholesteric liquid crystals (CLCs). [ 32–34 ] In this case, dual‐wavelength lasers can simultaneously emit two single‐mode lasing peaks that are separated by several nanometers.…”

“…Multicolor lasers show significant applications in the fields of wavelength division multiplexing communication, [1][2][3][4][5] highly sensitive optical sensors, [6][7][8][9] medical diagnosis, [10] laser displays, [11,12] and precise spectroscopy. [13,14] Up to now, dual-wavelength [1,[6][7][8]15] or dual-color lasers [16][17][18][19] have been achieved in several resonators such as grating, [20][21][22] heterogeneous structures, [17,12,23] single crystals, [3,19,24] fibers, [2,5,9,25,26] metal-organic framework, [24,27] plasmon resonances, [28][29][30] colloidal photonic of 60 µm. [58] Thus, surface-emitting triple-and quadruple-wavelength lasing has the potential to be realized in BPLCs, and relative mechanisms can be systematically investigated.…”

Simultaneous Dual-Wavelength Source Raman Spectroscopy with a Handheld Confocal Probe for Analysis of the Chemical Composition of In Vivo Human Skin

“…Its sensitive region covers 200–1100 nm, corresponding to the fingerprint (FP) region (450–1750 cm –1 ) of most organic chemicals, with 785 nm excitation. To get the high wavenumber (HW) region (2800–3800 cm –1 ) for water content analysis, several Raman spectroscopy systems − adopt a dual-wavelength light source by adding a 671 nm laser to extend the spectral range. However, FP and HW spectra need to be obtained separately during the acquisition by manually switching the laser and repeating the measurement, which may cause depth mismatch and prolonged acquisition time.…”

“…Besides, the fiber switch had high insertion loss (loss >40%), and it increased the system complexity. Recently, Kiefer proposed a Raman fusion spectroscopy utilizing simultaneous dual-wavelength excitation and on-chip spectra fusion . Univariate and multivariate data analyses were applied to analyze an aqueous dimethyl sulfoxide (DMSO) solution based on intensity variation for each pixel .…”

High-Frequency Raman Analysis in Biological Tissues Using Dual-Wavelength Excitation Raman Spectroscopy

“…An alternative method of extending the range is to use a second laser at shorter wavelength and this concept has been applied to CCD-based spectrometers in previous studies. [18][19][20] In this note, we will demonstrate an InGaAs detector-based dual-wavelength excitation Raman system that covers both the finger print region (240-1900 cm −1 ) and the high-frequency region (2390-4110 cm −1 ). In addition, we integrated a dual-laser fiber probe using off-theshelf components.…”