All-optical data inverter based on free-carrier absorption induced cross-gain modulation in Si quantum dot doped SiOx Waveguide
Journal
IEEE Journal on Selected Topics in Quantum Electronics
Journal Volume
20
Journal Issue
4
Date Issued
2014
Author(s)
Abstract
The Si quantum dot (Si-QD) doped SiO x waveguide based all-optical cross-gain data inverter is demonstrated. The data inversion response of the probe at 1550 nm depends on the dispersed carrier lifetime in Si-QD, which is strongly correlated with the intensity of pulsed pump at wavelength of 405 nm. The free-carrier absorption cross-section of Si-QD is determined as 3.1 �� 10 -17 cm 2 by fitting with four-level rate equations. Decreasing the pump power could maintain the band-filling effect in small Si-QDs and suppress the filling and scattering of excited free carriers to lower energy states in larger Si-QDs. This causes the carrier lifetime of Si-QD as well as the data inversion speed shortened from 35 to 19 �gs by reducing pump power from 240 to 66 mW. Shrinking the Si-QD size and narrowing its size distribution is beneficial to the carrier lifetime shortening and dispersion by overlapping the electron-hole wave functions under strong quantum confinement. The modulation bandwidth can be enhanced by releasing the heating effect in Si-QDs, which further shortens the free carrier absorption induced data inversion response to 9 �gs by shortening the pump duty-cycle from 10 to 0.5 �gs. The all-optical SiO x :Si-QD waveguide cross-gain data inverter with a pulsed on-off keying data rate of 200 kbit/s is reported.
SDGs
Type
journal article