Ultrafast optical devices for photonic integrated circuit applications

The transmission bandwidth of a modern fiber-optic communication systems depends on the modulation bandwidth of optical signal transmitters, as well as the computation speed of photonic components for optical signal processing. Nowadays, the rapid development of various bandwidth-hungry network products urges the research on optical transmitters and photonic circuits that could support high bit-rate optical signal communication and computation. The objective of this dissertation is to investigate on laser transmitters that allow ultrafast modulations, as well as on photonic integrated circuits components in nonlinear chalcogenide glass substrates that are capable of ultrafast all-optical signal processing.;Vertical cavity surface emitting lasers (VCSELs) offers superior properties as signal transmitters in the fiber-optic communication network, such as large modulation bandwidth, low coupling loss with optical fibers, and low fabrication cost. As the modulation bandwidth of VCSELs are limited due to their relaxation modulation frequency up to 20GHz, transverse mode lock of VCSEL is proposed to reach modulation bandwidth beyond 100GHz. Both the static emission and ultrafast dynamics of VCSELs' transverse modes were studied to explore their potential for mode locking.;All-optical signal processing with nonlinear photonic integrated circuits (PIC) is an effective solution to overcome the speed limitation arising from opto-electronic conversions in the modern communication network. Performance of individual components in a PIC and its scale of integration are influenced by its substrate material and its fabrication method. In this dissertation, nonlinear PIC components written in ChG substrates by ultrafast laser writing are studied, taking advantages of the unique material traits of chalcogenide glasses (ChGs), and the capability of ultrafast laser writing to fabricate 3D arbitrary structures in nearly any transparent materials. The fabrication challenges arising from the laser-material interaction were overcome, and basic nonlinear PIC components including waveguide Bragg gratings, nonlinear directional couplers and one dimensional waveguide arrays were designed and fabricated. Functionalities of these devices were demonstrated at a reduced power required for nonlinear operations, as compared to similar devices in silica substrates.;The results presented in this dissertation provide the basics for the realization of on-chip optical network for largely increased data transmission bandwidth and signal processing speed.