title: Influence of carrier lifetime on performance of silicon p-i-n variable optical attenuators fabricated on submicrometer rib waveguides.
abstract: We investigated influence of carrier lifetime on performance of silicon (Si) p-i-n variable optical attenuators (VOAs) on submicrometer Si rib waveguides. VOAs were fabricated with and without intentional implantation of lattice defects into their intrinsic region. Carrier lifetime was measured by pulse responses for normal incidence of picosecond laser pulse of 775 nm to the VOA, as approximately 1 ns and approximately 7 ns for the VOAs with and without defects, respectively. Carrier lifetime is determined by the sum of surface recombination and Auger recombination for VOAs without defects, while Schockley-Read-Hall recombination is dominant for the VOA with defects. As a result, attenuation efficiency (dB/mA) is 0.2-0.7 and 0.04-0.1, while 3-dB bandwidth is 40-100 MHz and over 200 MHz for the VOAs with and without defects, respectively. There is a trade-off relation between attenuation and response speed of the VOAs with respect to carrier lifetime i.e., attenuation efficiency is linearly proportional to the carrier lifetime, whereas response speed is inversely proportional to it.
authors.affiliation: NTT Microsystem Integration Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa, 243-0198, Japan. psbong@aecl.ntt.co.jp
authors.forename: Sungbong
authors.initials: S
authors.lastname: Park
authors.forename: Koji
authors.initials: K
authors.lastname: Yamada
authors.forename: Tai
authors.initials: T
authors.lastname: Tsuchizawa
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shinojima
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Nishi
authors.forename: Rai
authors.initials: R
authors.lastname: Kou
authors.forename: Sei-ichi
authors.initials: S
authors.lastname: Itabashi
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012666:Semiconductors; D012680:Sensitivity and Specificity