Background-suppressed SRS fingerprint imaging with a fully integrated system using a single optical parametric oscillator

Abstract

Stimulated Raman Scattering (SRS) imaging can be hampered by non-resonant parasitic signals that lead to imaging artifacts and eventually overwhelm the Raman signal of interest. Stimulated Raman gain opposite loss detection (SRGOLD) is a three-beam excitation scheme capable of suppressing this nonlinear background while enhancing the resonant Raman signal. We present here a compact electro-optical system for SRGOLD excitation which conveniently exploits the idler beam generated by an optical parametric oscillator (OPO). We demonstrate its successful application for background suppressed SRS imaging in the fingerprint region. This system constitutes a simple and valuable add-on for standard coherent Raman laser sources since it enables flexible excitation and background suppression in SRS imaging.

Advanced Label-Free Laser Scanning Microscopy and Its Biological Imaging Application

“…For CARSM, they are negligible by using excitation light with long wavelength, proper power and repetition rate [118][119][120]. In SRSM, nonlinear absorption is avoided for reducing the risk of photodamage and photobleaching because of background-free and long wavelength for excitation [118,121]. Furthermore, as involving only virtual state without energy deposition, SHGM brings little photodamage or photobleaching by increasing the repetition rate that keeps the peak intensity below damage threshold [122,123].…”

High‐power, continuous‐wave optical parametric oscillator based on MgO:sPPLT crystal

“…[1][2][3][4][5][6] The optical parametric oscillator (OPO) based on the quasi-phase matching (QPM) technology can realize the tuning and expansion of the laser wavelength, which provides more possibilities for laser applications in many fields of science and technology including laser measurement, 7,8 and fingerprint imaging. 9 Periodically poled LiNbO 3 (PPLN), MgO-doped PPLN (PPMgLN), and periodically poled LiTaO 3 (PPLT) crystals are commonly used. By changing the grating period and temperature of these periodically poled crystals, a tunable laser output covering visible to mid-infrared can be obtained to meet different needs.…”

“…Near‐infrared lasers have important applications in nonlinear optics, material processing, medical diagnosis, laser ranging, and other fields 1‐6 . The optical parametric oscillator (OPO) based on the quasi‐phase matching (QPM) technology can realize the tuning and expansion of the laser wavelength, which provides more possibilities for laser applications in many fields of science and technology including laser measurement, 7,8 and fingerprint imaging 9 . Periodically poled LiNbO 3 (PPLN), MgO‐doped PPLN (PPMgLN), and periodically poled LiTaO 3 (PPLT) crystals are commonly used.…”

Mitigating cross‐phase modulation artifacts in femtosecond stimulated Raman scattering

“…[ 7‐11 ] However, recent studies have shown that thermal lensing or thermal scattering, two‐photon (two‐color) absorption (TPA), and cross‐phase modulation (XPM) lead to parasitic signatures on the SRS signal. [ 12‐15 ] Especially, artifacts due to XPM distort the line shape of the stimulated Raman signal and become more relevant for high pulse energies and ultra‐short pulse durations as used in a number of experiments. [ 16‐20 ]…”