Stimulated Raman scattering spectroscopy with quantum-enhanced balanced detection.

Area of Science:

• Quantum optics
• Spectroscopy
• Molecular imaging

Background:

• Quantum-enhanced stimulated Raman scattering (QE-SRS) offers enhanced sensitivity beyond the shot noise limit.
• Previous QE-SRS demonstrations were limited by low optical power, hindering practical applications.

Purpose of the Study:

• To demonstrate a quantum-enhanced balanced detection (QE-BD) scheme for stimulated Raman scattering (SRS) spectroscopy.
• To enable QE-SRS to operate effectively with high-power optical pulses.

Main Methods:

• Generated pulsed squeezed vacuum at 844 nm with a -3.28 dB squeezing level using a LiTaO3 waveguide.
• Integrated squeezed vacuum into an SRS spectrometer with a high-speed spectral scanner.
• Acquired QE-SRS spectra in the 2000-2280 cm⁻¹ range within 50 ms.

Main Results:

• Successfully obtained QE-SRS spectra using high-power SRS pump pulses (11.3 mW average power).
• Achieved a signal-to-noise ratio (SNR) improvement of 2.27 dB compared to classical SRS with balanced detection.
• Demonstrated the viability of QE-SRS with high optical power.

Conclusions:

• The QE-BD scheme effectively enhances SRS spectroscopy sensitivity even with high optical power.
• This advancement makes QE-SRS a more competitive technique for sensitive molecular vibrational analysis.
• The developed method paves the way for advanced spectroscopic applications.