[11p-W935-1~11] 3.8 Optical measurement, instrumentation, and sensor

[11p-W935-6] Junction Capacitance Cancellation of Photodiode by Bootstrap Method in Noise Cancelling with Phase Detection Technique for Pump / probe Spectroscopy

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

Keywords:Laser spectroscopy, Noise cancellation, Stimulated Raman

In order to improve the signal-to-noise ratio (S/N) in a pump / probe method, which is used for such as an observation of stimulated Raman scattering, we have developed a phase detection technique to convert intensity change of probe light by sample measurement into pulse repetition phase modulation, independently of optical intensity noise. We found the S/N in the phase-detection technique was limited by the fluctuation of the junction capacitance of the photodiode due to the optical noise. In this research, we apply the bootstrap method to cancel the fluctuation of the junction capacitance. We achieve the shot noise limited performance. Additionally, we investigate the effect of the Q value of the resonance circuit used for the load of the photodiode.