Abstract
We demonstrate reduction of the free-carrier lifetime in a silicon nanowaveguide from 3 ns to 12.2 ps by applying a reverse bias across an integrated p-i-n diode. This observation represents the shortest free-carrier lifetime demonstrated to date in silicon waveguides. Importantly, the presence of the p-i-n structure does not measurably increase the propagation loss of the waveguide. We derive a figure of merit demonstrating equal dependency of the nonlinear phase shift on free-carrier lifetime and linear propagation loss.
Highlights
Nonlinear optical processes in silicon such as Raman scattering [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] and oscillation [17,18,19,20,21], self- [22,23,24,25,26] and cross-phase modulation [27], and four-wave mixing [28,29,30,31,32,33,34,35,36,37] have enabled a number of demonstrations of devices that can operate at low powers, have small, micron-scale footprints, and can be fully integrated along with electronics in a CMOSplatform
The two major nonlinear optical loss mechanisms in silicon waveguides at communications wavelengths are two-photon absorption (TPA) and free-carrier absorption (FCA) [10,38]
Two-photon absorption is a result of the proximity of the band edge to communication wavelengths and is unavoidable when operating in this wavelength range
Summary
Nonlinear optical processes in silicon such as Raman scattering [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] and oscillation [17,18,19,20,21], self- [22,23,24,25,26] and cross-phase modulation [27], and four-wave mixing [28,29,30,31,32,33,34,35,36,37] have enabled a number of demonstrations of devices that can operate at low powers, have small, micron-scale footprints, and can be fully integrated along with electronics in a CMOSplatform. Received 29 Oct 2009; revised 15 Jan 2010; accepted 27 Jan 2010; published 4 Feb 2010 15 February 2010 / Vol 18, No 4 / OPTICS EXPRESS 3584 we derive a figure of merit for nonlinear optical processes in silicon waveguides, which shows the equal dependence of the maximum nonlinear performance on the free-carrier lifetime and propagation loss
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