25 October 2005 Thermo-opto-electrical analysis of an optical modulator integrated in a silicon planar structure
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Interest in silicon as a material for optoelectronics has increased year after year. We propose numerical analysis of an integrated waveguide-vanishing-based modulator realized by ion implantation in SOI wafer. The active region is 3×3 μm2 and the lateral confinement is guaranteed by two highly-doped As (8×1019cm-3) and B (2×1019cm-3) implanted regions 1-μm-deep. This type of structure allows to obtain a planar device, avoiding structural steps which are harmful for photolithography processes. The resulting channel waveguide shows single mode operation and propagation losses of about 1.8 dB/mm, which are acceptable for short structures. The modulation is based on a lateral p-i-n diode, which injects free carriers into the rib volume between the doped regions. We have optimized the device for maximum injection efficiency for a given applied voltage. The resulting optical behavior can be explained by the lateral confinement vanishing that transforms the rib waveguide in a slab waveguide, once the rib is full of free carriers. This phenomenon occurs at driving voltage of about 1.0 V, with electrical power consumption below 1 mW, and implies a rapid variation of the propagating characteristics, and as consequence an optical beam lateral redistribution into the structure. Results show that an optical modulation depth close to 100% can be reached with a switching time of about 30 ns. A set of numerical simulations has been performed in order to evaluate the thermal response of the device and thus to estimate the thermo-optic effect related to the biasing of the device itself. The main advantages of this device are the low cost and full integrability with electronic devices; thus the device can be suitable in many application fields.
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Rocco C. Zaccuri, Rocco C. Zaccuri, Giuseppe Coppola, Giuseppe Coppola, Mario Iodice, Mario Iodice, Antonella Sciuto, Antonella Sciuto, Sebania Libertino, Sebania Libertino, "Thermo-opto-electrical analysis of an optical modulator integrated in a silicon planar structure", Proc. SPIE 6013, Optoelectronic Devices: Physics, Fabrication, and Application II, 60130K (25 October 2005); doi: 10.1117/12.632085; https://doi.org/10.1117/12.632085

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