7 March 2005 All-optical modulation in thin film silicon-based waveguiding structures
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Abstract
Infrared absorption photoinduced by visible light in a-SixC1-x:H is characterized by in guide pump and probe measurements in order to test its applicability to a low-cost micromodulator, fully integrable as a post-processing on-top of a standard microelectronic chip. The Photoinduced Absorption phenomenon in amorphous silicon arises from an alteration of the defect state population by decay of carriers photogenerated by visible light. These levels, deep in the gap, are strongly involved in interactions with IR radiation, and then the VIS illumination modifies their optical properties by increasing the IR absorption coefficient value. Test waveguiding devices are fabricated by Plasma Enhanced Chemical Vapour Deposition on silicon wafers, at temperatures lower than 180°C, and consist of a a-SiC:H/oxide stack. In particular, devices having a-SixC1-x:H cores with different doping and different carbon concentration are characterized. The 1.55 μm probe radiation generated by a DFB laser diode is efficiently transmitted through the a-SixC1-x core thanks to the step index waveguide structure. The pump system consists of low cost AlInGaP LEDs pulsed by a function generator, for an illumination intensity ranging from 0.15 up to 0.85 mW/mm2. Results show that the modulation effect increase for longer pump penetration depth and for higher doping concentration. The phenomenon strongly depends on the carbon introduction in a-Si:H. Digital transmissions tests at 300 kbit/s were performed.
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Francesco Giuseppe Della Corte, Francesco Giuseppe Della Corte, Massimo Gagliardi, Massimo Gagliardi, Krzysztof Malecki, Krzysztof Malecki, Maria Arcangela Nigro, Maria Arcangela Nigro, Caterina Summonte, Caterina Summonte, } "All-optical modulation in thin film silicon-based waveguiding structures", Proc. SPIE 5730, Optoelectronic Integration on Silicon II, (7 March 2005); doi: 10.1117/12.590574; https://doi.org/10.1117/12.590574
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