Continuous-wave light modulation using stimulated Raman scattering

Albina I. Sokolovskaya

V. A. Zubov, M. M. Sushchinskiǐ, I. K. Shuvalov

Jonathan Tyler Green, Joshua J. Weber, Deniz D. Yavuz

By using continuous-wave (CW)--stimulated Raman scattering inside a high-finesse cavity, we generate three CW spectral components covering about one octave of optical bandwidth. We investigate the mutual coherence of these three beams by studying phase-dependent second harmonic generation. From the high contrast of the observed interference fringes, we infer very good phase coherence across the spectrum and thereby infer the synthesis of a near single-cycle optical wave form.

Kazuki Ihara, Chihiro Eshima, Shin-ichi Zaitsu +4 more

An ultrafast light-intensity modulator, based on stimulated Raman scattering, is described. The intensity of a continuous wave laser is fully modulated at 17THz using hydrogen in a high-finesse cavity. The modulation frequency is determined by the molecular constant of the Raman medium, i.e., the Raman shift frequency. The modulation frequency can be changed in the tetrahertz range by replacing the Raman medium. Due to the accurate modulation frequency and the high beam coherence, this device is amenable to a variety of applications such as in basic science and also in advanced industrial technology.

G V Venkin, Iu. A. Il'Inskii, A. S. Mkoyan

Rayssa B. de Andrade, Hugo Kerdoncuff, Kirstine Berg‐Sørensen +3 more

Stimulated Raman spectroscopy has become a powerful tool to study the spatiodynamics of molecular bonds with high sensitivity, resolution, and speed. However, the sensitivity and speed of state-of-the-art stimulated Raman scattering spectroscopy are currently limited by the shot-noise of the light beam probing the Raman process. Here, we demonstrate in a proof-of-principle experiment an enhancement of the sensitivity of continuous-wave stimulated Raman spectroscopy by reducing the quantum noise of the probing light below the shot-noise limit by means of amplitude squeezed states of light. Probing polymer samples with Raman shifts around 2950 c m − 1 with squeezed states, we demonstrate a quantum enhancement of the stimulated Raman signal-to-noise ratio (SNR) of 3.60 dB relative to the shot-noise limited SNR. Our proof-of-concept demonstration of quantum-enhanced continuous-wave Raman spectroscopy paves the way for more elaborate demonstrations using state-of-the-art stimulated Raman scattering microscopes, and thus constitutes the very first step towards a new generation of Raman microscopes, where weak Raman transitions can be imaged without the use of markers or an increase in the total optical power.