A Stimulated Raman Scattering CMOS Pixel Using a High-Speed Charge Modulator and Lock-in AmplifierReportar como inadecuado




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1

Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Nakaku, Hamamatsu, Shizuoka 432-8011, Japan

2

Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan





*

Author to whom correspondence should be addressed.



Academic Editor: Vittorio M. N. Passaro

Abstract A complementary metal-oxide semiconductor CMOS lock-in pixel to observe stimulated Raman scattering SRS using a high speed lateral electric field modulator LEFM for photo-generated charges and in-pixel readout circuits is presented. An effective SRS signal generated after the SRS process is very small and needs to be extracted from an extremely large offset due to a probing laser signal. In order to suppress the offset components while amplifying high-frequency modulated small SRS signal components, the lock-in pixel uses a high-speed LEFM for demodulating the SRS signal, resistor-capacitor low-pass filter RC-LPF and switched-capacitor SC integrator with a fully CMOS differential amplifier. AC modulated components remained in the RC-LPF outputs are eliminated by the phase-adjusted sampling with the SC integrator and the demodulated DC unmodulated components due to the SRS signal are integrated over many samples in the SC integrator. In order to suppress further the residual offset and the low frequency noise 1-f noise components, a double modulation technique is introduced in the SRS signal measurements, where the phase of high-frequency modulated laser beam before irradiation of a specimen is modulated at an intermediate frequency and the demodulation is done at the lock-in pixel output. A prototype chip for characterizing the SRS lock-in pixel is implemented and a successful operation is demonstrated. The reduction effects of residual offset and 1-f noise components are confirmed by the measurements. A ratio of the detected small SRS to offset a signal of less than 10−5 is experimentally demonstrated, and the SRS spectrum of a Benzonitrile sample is successfully observed. View Full-Text

Keywords: stimulated Raman scattering; CMOS image sensor; lock-in amplifier; low frequency noise; double modulation; Raman shift stimulated Raman scattering; CMOS image sensor; lock-in amplifier; low frequency noise; double modulation; Raman shift





Autor: De Xing Lioe 1, Kamel Mars 1, Shoji Kawahito 1,* , Keita Yasutomi 1, Keiichiro Kagawa 1, Takahiro Yamada 2 and Mamoru Hashimoto 2

Fuente: http://mdpi.com/



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