[14p-B409-1~15] 3.8 Optical measurement, instrumentation, and sensor

[14p-B409-13] Intensity Noise Cancellation of White Pulsed Probe Light Based on Time Division Discrimination for Multi-Channel Spectroscopy in Pump/probe measurement

〇Keisuke Seto¹, Takayoshi Kobayashi², Eiji Tokunaga¹ (1.Tokyo Univ. Sci., 2.Univ. Electro-Commun.)

Keywords:Laser spectroscopy, Noise cancellation, Stimulated Raman

The spectral multi-channel lock-in detection with the supper continuum (SC) probe pulsed light enables one-shot molecular vibrational spectroscopy. However, the SC light has notorious intensity noise, and signal-to-noise ratio (S/N) is significantly degraded by the noise. In this study, we multiplex the probe and reference pulsed beams in the manner of time-division multiplexing. The reference pulsed beam is delayed by a half of the pulse repetition period and spatially superposed on the probe beam. They are demultiplexed after measuring a sample and took the difference to cancel the intensity noise. We demonstrate a near shot-noise-limited S/N performance (4-dB inferior to the shot noise) based on this technique with 1-μW average power of the probe and reference lights.