title: A Stimulated Raman Scattering CMOS Pixel Using a High-Speed Charge Modulator and Lock-in Amplifier.
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.
authors.affiliation: Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Nakaku, Hamamatsu, Shizuoka 432-8011, Japan. lioe@idl.rie.shizuoka.ac.jp.
authors.forename: De Xing
authors.initials: de X
authors.lastname: Lioe
authors.affiliation: Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Nakaku, Hamamatsu, Shizuoka 432-8011, Japan. kamel@idl.rie.shizuoka.ac.jp.
authors.forename: Kamel
authors.initials: K
authors.lastname: Mars
authors.affiliation: Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Nakaku, Hamamatsu, Shizuoka 432-8011, Japan. kawahito@idl.rie.shizuoka.ac.jp.
authors.forename: Shoji
authors.initials: S
authors.lastname: Kawahito
authors.affiliation: Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Nakaku, Hamamatsu, Shizuoka 432-8011, Japan. kyasu@idl.rie.shizuoka.ac.jp.
authors.forename: Keita
authors.initials: K
authors.lastname: Yasutomi
authors.affiliation: Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Nakaku, Hamamatsu, Shizuoka 432-8011, Japan. kagawa@idl.rie.shizuoka.ac.jp.
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Kagawa
authors.affiliation: Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan. yamada@sml.me.es.osaka-u.ac.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan. mamoru@me.es.osaka-u.ac.jp.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Hashimoto
keywords: CMOS image sensor; Raman shift; double modulation; lock-in amplifier; low frequency noise; stimulated Raman scattering