Publications (3)1.49 Total impact
Conference Proceeding: Low loss amorphous silicon photonic wire and ring resonator fabricated by CMOS process[show abstract] [hide abstract]
ABSTRACT: We report low loss amorphous photonic wire loss of 3.5dB/cm. We also report compact racetrack ring resonators with Q factor greater than 20,000. The photonic circuit is fabricated with standard CMOS production tools.Optical Communication - Post-Deadline Papers (published 2008), 2007 33rd European Conference and Exhibition of; 10/2007
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ABSTRACT: We report low loss amorphous photonic wire loss of 3.5dB/cm. We also report compact racetrack ring resonators with Q factor greater than 20,000. The photonic circuit is fabricated with standard CMOS production tools. Introduction Silicon photonic integrated circuit is a very attractive platform for a wide range of application. High index contrast enables small bending radius subsequently resulting in a much denser circuitry. Crystalline SOI material is used in almost all silicon photonic circuitry . While it typically has exceptional material quality it limits the photonic circuit to a single layer. As an alternative, deposited silicon facilitates multi layer stacking of photonic layers and is CMOS compatible. However, for this the deposited material should have similar quality in terms of optical properties as the crystalline silicon. Various deposited silicon materials have already been explored, such as SiON, SiN, SiC, Poly-Si, a-Si. Si can be deposited using various deposition processes. The property of the film depends on the process used and process conditions. In this work we explore a low temperature plasma-enhanced CVD process to deposit high-quality amorphous silicon (a-Si). Other groups using similar processes have already demonstrated single-mode waveguides fabricated from hydrogenated a-Si have with a loss of 2 dB/cm (shallow etch)  and 6.5dB/cm (deep etch) . Design and fabrication Single mode operation and strong optical confinement is a prerequisite for high density photonic integrated circuitry. The strong confinement is necessary for making circuits with small (1-5μm) bending radius with low loss . Photonic wires of 220nm height and 500nm width can be used for this purpose . To measure the propagation loss wires of varying length are made by spiraling them with large bending radius (20μm). The length of the photonic wires varies between 0.5cm and 40cm. Along with the spirals all-pass notch filters with race track ring resonators were also added to the design. The bend radius is 4μm and coupling gap is 180nm. To build a-Si photonic circuitry we start with bare silicon wafers. An overview of the fabrication process is depicted in figure 1. A 2μm silicon dioxide is deposited by high density plasma. The deposition process is followed by chemical mechanical polish (CMP) to prepare the surface for a-Si deposition. The thickness loss due to CMP is compensated by an excess deposition in the first step.
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ABSTRACT: We report the fabrication of low-loss amorphous silicon photonic wires deposited by plasma enhanced chemical vapor deposition. Single mode photonic wires were fabricated by 193 nm optical lithography and dry etching. Propagation loss measurements show a loss of 3.46 dB/cm for photonic wires and 1.34 dB/cm for ridge waveguides.Optics Communications 282(9):1767-1770. · 1.49 Impact Factor