Two Dimensional Silicon Photonic Crystal Band Gap Applications for Optical Bio-sensing and Modulation

Kılıç, Selahattin Cem
In this thesis, we presented mainly two applications that utilize two dimensional Silicon photonic crystals. One application is an optical refractive index based gas/bio-sensor. The device is constructed by rod-type square lattice photonic crystal cavity. The rod-type is chosen to confine the electric field in the low-index medium and maximize the light-matter interaction. The resonance characteristics is selected as Fano-like resonance due to its sharp and asymmetric shape that is suitable for such an application. The rods are sandwiched between two metal plates so that the out-ofplane light confinement is achieved by reflection. First the theory of the design is described and numerical analysis and characterization of the device is conducted. An air gap is introduced on top of the rods which acts like a slot structure to confine the light a spatially small region, decreasing the mode-volume and also increasing the sensitivity by amplifying light-matter interaction further. By introducing an internal tuning mechanism the size of the air gap is externally controlled by an electrical signal. This results in the resonance frequency of the device is externally controlled so that the design is highly suitable for different operation regions, environmental and fabrication errors. Another application is the experimental confirmation of a two dimensional photonic crystal Mach-Zehnder interferometer that is being utilized as an optical modulator. The modulation is done by optical carrier injection method by utilizing plasma dispersion effect and taking advantage of the negative refractive index phenomenon which achieves a much smaller phase-shifter length compared to the similar devices in the literature.


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Erdil, Mertcan; Kocaman, Serdar; Department of Electrical and Electronics Engineering (2020)
In this thesis, we presented a refractive index based optical bio-sensor, utilizing a slot mode one dimensional photonic crystal cavity as a transducing element. We benefited from the suitability of slotted one dimensional photonic crystal cavities for optical bio-sensing applications, owing to their capability of confining the light strongly in the low dielectric media. We described the theory behind the design, and also provided numerical analyses, characterizing the device performance. We also demonstrat...
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Photonic integrated circuit components with amorphous structures
Sarıhan, Murat Can; Kocaman, Serdar; Department of Electrical and Electronics Engineering (2018)
In this thesis work, amorphous photonic materials, which are an alternative to photonic crystals and offering flexibility and comparable performance, are designed for photonic integrated circuits and analyzed. A design guideline is presented for the first time with experimental verification in telecommunication wavelengths. Amorphous photonic materials are artificially designed materials that possessing random refractive index distributions and has photonic band gaps due to the inherent short-range order. F...
Tunable integrated optical modulator with dynamical photonic band transition of photonic crystals
GÖVDELİ, ALPEREN; Kocaman, Serdar (2019-01-01)
A Mach-Zehnder Interferometer based optical modulator composed of photonic crystals as phase shifters is presented. The switching process relies on the phase modulation along the arms of interferometer resulted from the photonic band shift of the photonic crystal regions. A small bulk index change leads to a large effective index difference between two arms of the interferometer and a small foot-print device can operate as a modulator. Presented MZI-based optical modulator is shown to have tunable bandwidth...
Rigorous designs of nano-optical couplers and absorbers with photonic crystals involving irregular arrays and nonidentical elements
Yazar, Şirin; Ergül, Özgür Salih; Department of Electrical and Electronics Engineering (2021-9)
This thesis presents design and analyses of compact and effective nano-optical couplers and absorbers based on photonic crystals. Single-input and double-input nano-optical couplers that provide electromagnetic wave transmission in desired directions are designed, and important parameters regarding their transmission efficiency are investigated. These designs are further cascaded by adding one after another to create nano-optical transmission systems, whose transmission characteristics are also examined. In...
Citation Formats
S. C. Kılıç, “Two Dimensional Silicon Photonic Crystal Band Gap Applications for Optical Bio-sensing and Modulation,” M.S. - Master of Science, Middle East Technical University, 2021.