Coherently broadened, high-repetition-rate laser for stimulated Raman scattering–spectroscopic optical coherence tomography

Abstract

We present a novel light source specifically tailored for stimulated Raman scattering–spectroscopic optical coherence tomography (SRS-SOCT), which is, to the best of our knowledge, a novel molecular imaging method that combines the molecular sensitivity of SRS with the spatial and spectral multiplexing capabilities of SOCT. The novel laser consists of an 8 W, 450 fs Yb:KGW oscillator, with a repetition rate of 40 MHz, which delivers the Stokes beam for SRS-SOCT and also pumps and amplifies an optical parametric oscillator (OPO). The output of the amplified OPO is then frequency doubled and coherently broadened using a custom-made tapered fiber that generates bandwidth pulses >40 nm, compressible to <50 fs, with the average power over 150 mW, near the shot-noise limit above 250 kHz. The broadened and compressed pulse simultaneously serves as the pump beam and SOCT light source for SRS-SOCT. This light source is assessed for SRS-SOCT, and its implications for other imaging methods are discussed.

Label-free detection of brain tumors in a 9L gliosarcoma rat model using stimulated Raman scattering-spectroscopic optical coherence tomography

“…We recently introduced an ultrafast laser system specially designed for SRS-SOCT. 26 The schematic of the system is shown in Fig. 1(b) .…”

“…The SRS signal shares the same axial resolution as OCT, but as with any SOCT method, the molecular signatures accumulate along depth. 25 , 26 The SRS-SOCT signal scaling with pump and Stokes power has been rigorously characterized in our prior work using well controlled synthetic samples and fresh tissues. 25 , 26 …”

“… 25 , 26 The SRS-SOCT signal scaling with pump and Stokes power has been rigorously characterized in our prior work using well controlled synthetic samples and fresh tissues. 25 , 26 …”

“…In this work, we apply a method, called stimulated Raman scattering-spectroscopic optical coherence tomography (SRS-SOCT), 25 , 26 and assess its potential to identify tumor margins for image-guided neurosurgery. SRS-SOCT combines the spatial and spectral multiplexing capabilities of SOCT with the molecular sensitivity and specificity of SRS to provide fast, label-free, tomographic molecular information, thus overcoming the limitations of each individual technique (OCT and SRS).…”

Multi-modal Nonlinear Optical and Thermal Imaging Platform for Label-Free Characterization of Biological Tissue

“…The ability to sense neuronal membrane potential and calcium activity with combined SRS and calcium-sensitive MPF has been demonstrated to show the capacity of SRS for label-free sensing of neuronal action potentials (24,25). Integration of SRS with optical coherence tomography (OCT) has been shown to augment nonspecific scattering-based contrast with vibrational specificity to image lipid distributions in excised human adipose tissue (37,38). More recently, researchers have employed four or more nonlinear imaging modalities, including CARS, MPF, SHG, and third harmonic generation for live tissue and intravital imaging towards wound healing and cancer metastasis (26,27,39).…”