Optoelectronics and Photonics Engineering MS Thesis Defense by Hüseyin Ozan Çirkinoğlu

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KOÇ UNIVERSITY

GRADUATE SCHOOL OF SCIENCES & ENGINEERING

OPTOELECTRONICS AND PHOTONICS ENGINEERING

MS THESIS DEFENSE BY HÜSEYİN OZAN ÇİRKİNOĞLU

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Title: Excitation of Silicon and Diamond Microsphere Whispering Gallery Modes by Femtosecond Laser Written Glass and Diamond Waveguides, and a Glass Fiber Coupler

Speaker: Hüseyin Ozan Çirkinoğlu

Time: August 21, 2017, 12:00

Place: ENG 120

Koç University

Rumeli Feneri Yolu

Sariyer, Istanbul

Thesis Committee Members:

Prof. Ali Serpengüzel (Advisor, Koc University)

Prof. Alper Kiraz (Koc University)

Assistant Prof. Onur Ferhanoğlu (Istanbul Technical University)

Abstract:

Whispering gallery modes (WGMs) are the optical resonances, where light is trapped inside a dielectric and symmetric cavity by total internal reflection (TIR) on the boundary facets. Due to the unique optical properties, such as very high quality factors, and very narrow linewidths, due to the long photon lifetime inside the cavity, and confinement of the field in very small mode volumes, resulting in high power densities; cavities of different geometries, supporting WGMs, have been extensively studied for more than four decades now. However, the efficient coupling to WGMs mostly rely on experimentally challenging schemes including prism coupling, optical fiber half coupling (OFHC) or free space coupling. This thesis consist of the excitation of silicon microsphere WGMs using an alternative coupling method: shallow waveguides fabricated by femtosecond laser inscription. The evanescent field coupling of the guided modes by the femtosecond micromachined glass and diamond waveguides have been used to excite microsphere WGMs. Furthermore, this thesis includes the excitation of a diamond sphere using an OFHC. Employment of diamond material in photonic applications is substantial, because among all materials, diamond exhibits unique optical properties such as its color centers, large band-gap, high Raman gain, as well as a unique crystal lattice, and robust physical properties. Utilizing diamond as an excitation waveguide material or the cavity material opens the way for combination of both diamond’s and WGMs’ unique properties for applications in electronics, quantum information processing, and sensing.