Analysis and characterization of slab-coupled optical waveguide amplifiers and lasers

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 136-140).Semiconductor optical devices are important in the photonics industry due to their significant advantages in size, weight, and power consumption (SWAP) and to their capability for photonic integration. However, these devices traditionally suffer from low fiber coupling efficiency and have been limited to relatively low power applications. This thesis explores the potential of the slab-coupled optical waveguide (SCOW) semiconductor gain medium for use in high power optical amplifiers and external cavity lasers. The thesis begins by introducing the SCOW concept and describing the benefits of utilizing a low optical confinement design for high power operation. Detailed analysis and measurements of the output power, gain, and noise properties of slab-coupled optical waveguide amplifiers (SCOWAs) and slab-coupled optical waveguide external cavity lasers (SCOWECLs) are also presented. It will be shown that these devices not only exhibit Watt class output power with high coupling efficiency (> 90 %) but also demonstrate the capability for low noise operation.by William Loh.S.M

Signal and filtering using microwave-photonic generation links

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 283-291).The spectral purity of every oscillator system is limited by noise. This thesis explores the physics and measurements of noise fundamental to oscillators operating in the electrical and optical domains. Our analysis leads to a unified theory of phase noise applicable to perturbations whose characteristics are both white and colored. To minimize phase noise, the oscillator delay length must be made long. This principle motivates us to study a recent class of hybrid optoelectronic oscillators (OEOs) that operate based on concepts of microwave-photonic (MWP) gain. The delay of an OEO is made long (1-15 km) by taking advantage of the low losses afforded by optical fiber. Furthermore, the additional sidemodes are suppressed by a process of superhomogeneous gain exhibited by the MWP link. In this work, we demonstrate an OEO comprising of high-power low-noise slab-coupled optical waveguide (SCOW) components. The use of SCOW technology enables low-noise oscillation without the need for additional external amplification. We also show results of a similar system based on a SCOW coupled optoelectronic oscillator (COEO) configuration whose operation resembles that of a regeneratively modelocked laser. Both oscillators achieve phase noise significantly lower than that of conventional free-running microwave oscillators. Our ultimate goal is the monolithic integration of the OEO onto a single chip of InP. Towards that end, we will show our development of a SCOW distributed feedback laser (DFB) as a replacement to the bulky pump laser currently employed in the OEO.by William Loh.Ph. D