title: Broadband multiple-cascaded integration of electroabsorption modulators and high impedance transmission lines by lowering standing-wave effect.
abstract: Standing wave effect of applied electrical field on optical modulation in multiple-cascaded integration (CI) electroabsorption modulator (EAM) and high-impedance transmission line (HITL) has been investigated in this paper. As modulation frequency is increased to the scale that electrical wavelength is in the order of optical modulator length, multiple electrical reflection and self-interference on impedance-mismatch boundaries becomes significant, leading to strong position-dependent field distribution and degrading modulation bandwidth. Sharp bandwidth roll of electrical-optical (EO) conversion by standing wave has been found experimentally in CI structure, consistent with simulation results. By comparing different segment number and length of CI- structure, larger section number of design can overcome such problem to get more flatten bandwidth response. Such simple CI for 300μm long EAM has been demonstrated with flat EO response of -3dB drop 45GHz and -10dB microwave reflection (up to 65GHz) in 6-segement device, suggesting this scheme design is quite useful for efficient broad band modulation.
authors.affiliation: Institute of Electro-Optical Engineering and Department of Photonics, Semiconductor Technology Research Development Center, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: Jui-Pin
authors.initials: JP
authors.lastname: Wu
authors.forename: Rui-Ren
authors.initials: RR
authors.lastname: Chen
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Chiu