Fiber-dispersive Raman spectrometer with single-photon sensitivity.

Area of Science:

• Spectroscopy
• Photonics
• Materials Science

Background:

• Raman spectroscopy faces challenges with low signal intensity and interfering luminescence.
• Existing detectors like avalanche single-photon detectors have limitations in spectral sensitivity and timing resolution.

Purpose of the Study:

• To develop a novel fiber-dispersive Raman spectrometer to overcome low signal intensity and luminescence interference.
• To enhance spectral resolution and sensitivity in Raman measurements.

Main Methods:

• Utilized a fiber-dispersive Raman spectrometer with pulsed excitation.
• Employed a superconducting nanowire single-photon detector (SNSPD) for high sensitivity and timing resolution.
• Exploited chromatic dispersion in optical fibers for time-domain separation of Raman scattering and luminescence.

Main Results:

• Achieved effective separation of Raman scattering and luminescence through time-correlated measurements.
• Demonstrated broad spectral sensitivity (UV to near-IR) and high timing resolution with SNSPDs.
• Estimated spectral resolution of 3-10 cm⁻¹ (785 nm excitation) and <5 cm⁻¹ (532 nm excitation) over a 4400 cm⁻¹ range.

Conclusions:

• The novel fiber-dispersive Raman spectrometer effectively addresses key limitations in spontaneous Raman scattering measurements.
• The use of SNSPDs significantly enhances spectrometer performance compared to avalanche single-photon detectors.
• This technology offers improved spectral resolution and sensitivity for advanced material characterization.