The aim of this thesis is to contribute to the understanding of the dynamics of semiconductor lasers on a 10 to 100 ps time scale when their output is altered by external feedback. The optimization of parameters involved in optoelectronic feedback results in a reduction in the measured minimum pulse FWHM relative to previous work, and gives the conditions necessary to produce 25 ps FWHM optical pulses using this technique. To aid in the understanding of the modelocking of diode lasers, the CW spectral and threshold characteristics of a diode laser coupled to a mirror external cavity are examined. It is found that multiple reflections in the compound cavity cause an increase:). in mode linewidth with increasing bias current up to a maximum for a particular level of feedback for an external mirror coupled laser, but not for a grating coupled laser. As a result of the CW optical feedback analysis, grating feedback is utilized as a probe of the laser gain in a refinement of a previously reported technique for direct gain measurement. Also, the total loss reduction induced by external optical feedback is found to be made up of the sum of mirror loss and mode propagation loss reductions. This has significance in simulations of active modelocking and injection locking tuning characteristics carried out in this work. Simulations for active modelocking of a diode laser with low residual facet reflectivity in. an external mirror cavity account for the previously unexplained extreme sensitivity of the modelocking process to oscillator stability. Grating external cavity injection locking experiments and simulations present a new scheme for obtaining nearly transform limited optical pulses using semiconductor lasers. / Thesis / Master of Engineering (ME)

No description available.

by Ho Wai Hung. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1988. / Bibliography: leaves 81-83.

A densely and monolithically integrated photonic chip on indium phosphide is greatly in need for data transmission but the present day’s level of integration in InP is very low. Silicon enjoys a unique position among all the semiconductors in its level of integration. But it suffers from its slow signal transmission between the circuit boards and between the chips as it uses conventional electronic wire connections. This being the bottle-neck that hinders enhanced transmission speed, optical-interconnects in silicon have been the dream for several years. Suffering from its inherent deficient optical properties, silicon is not supposed to offer this feasibility in the near future. Hence, integration of direct bandgap materials, such as indium phosphide on silicon, is one of the viable alternatives. This thesis addresses these two issues, namely monolithic integration on indium phosphide and monolithic integration of indium phosphide on silicon. To this end, we use two techniques, namely selective epitaxy and heteroepitaxy by employing hydride vapor phase epitaxy method. The first part deals with the exploitation of selective epitaxy for fabricating a discrete and an integrated chip based on InP. The former is a multi-quantum well buried heterostructure laser emitting at 1.55 µm that makes use of AlGaInAs and InGaAsP as the barrier and well, respectively. We demonstrate that even though it contains Al in the active region, semi-insulating InP:Fe can be regrown. The lasers demonstrate threshold as low as 115A/cm2/quantum well, an external quantum efficiency of 45% and a characteristic temperature of 78 K, all at 20 oC. Concerning the integrated device, we demonstrate complex and densely packed buried arrayed waveguide (AWG) structures found in advanced systems-on-the-chip for optical code-division multiple-access (O-CDMA). We present a case of an error-free 10 Gb/s encoding and decoding operation from an eight-channel AWGs with 180 GHz channel spacing. Selective epitaxial growth aspects specific to these complicated structures are also described and guidance on design implementation of these AWGs is given. Mass transport studies on these AWGs are also presented. The second part deals with various studies on and relevant to epitaxial lateral overgrowth (ELOG) of high quality InP on silicon. (i) ELOG often encounters cases where most part of the surface is covered by mask. From the modeling on large mask area effects, their impact on the transport and kinetic properties has been established. (ii) It is known that ELOG causes strain in the materials. From synchrotron X-ray measurements, strain is shown to have large effect on the mask edges and the underlying substrate. (iii) The combination of strain and the influence of image forces when reducing the opening dimensions in ELOG has been modeled. It is found to be very beneficial to reduce openings down to ~100 nm where effective filtering of dislocations is predicted to take place even in vicinity of the openings. We call it nano-ELOG. (iv) By combining the modeling results of nano-ELOG and of a pre-study of ELOG on pure InP, a novel net pattern design is invented and experimented for nano-ELOG of InP on Si. PL measurements together with transmission electron microscopy observations indicate beneficial effects of small size openings (200 nm) compared to 1000 nm openings. (v) ELOG of InP on silicon-on-insulators together with a multi-quantum well structure grown on it has been demonstrated for the first time. This is particularly interesting for integrating silicon/silicon dioxide waveguides with InP. / QC 20100902

Thesis (M.S.) in Electrical Engineering--University of Maine, 2001. / Includes vita. Includes bibliographical references (leaves 74-77).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph.D.)--McMaster University, 2004. / Advisor: Daniel T. Cassidy. Includes bibliographical references (p. 124-127).

published_or_final_version / Business Administration / Master / Master of Business Administration

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 44-48). Also available in electronic version. Access restricted to campus users.

Thesis (M.S.)--Oregon Graduate Center, 1988.