All-optical amplification, modulation, and wavelength conversion based on the quantum confinement effect in the Si-QD doped SiOx/SiNx waveguide
Date Issued
2014
Date
2014
Author(s)
Wu, Chung-Lun
Abstract
All-optical amplification, modulation, and wavelength conversion have been demonstrated by using the Si-QD doped in SiOx/SiNx waveguide.
In the first part, the bandgap energy and radiative recombination rate of the Si-QD are theoretically simulated by the finite potential well approximation. The luminescent mechanisms, including NOV, E''d defect and Si-QDs related spontaneous emission, in SiOx:Si-QD are clearly distinguished by combining the PL with TRPL analysis. The small-signal gain of the SiOx:Si-QD waveguide is demonstrated by injecting the modulated probe signal into the optically pumped Si-QDs. The small-signal gain of 14.7 dB/6.5 dB at 785-/650-nm are measured in the SiO1.24:Si-QD/SiO1.42:Si-QD waveguide amplifiers. By considering the power-dependent gain coefficient in the Si-QD based waveguide amplifier, the peak power gain and saturation power in the Si-QD based waveguide amplifiers are determined.
In the second part, the free-carrier absorption in the Si-QD is utilized to demonstrate the all-optical FCA modulator. The FCA cross-section at 1550 nm is reduced from 2.8*10-17 cm2 to 8*10-18 cm2 with shrinking Si-QD size from 4.3 nm to 1.7 nm. Although the FCA cross-section is degraded when shrinking the Si-QD size, the free-carrier relaxation lifetime in SiOx:Si-QD waveguide is shortened from ~10 us to 0.48 us due to the increased momentum overlapping factor of electron-hole wave-functions in Si-QDs. The achievable bit rate of the inverted data modulation with RZ-OOK data format at 1550 nm has been significantly increased from 100 kbit/s to 2 Mbit/s by shrinking Si-QD size from 4.3 nm to 1.7 nm.
In the rest part, the nonlinearity of the Si-QD doped in SiNx matrix and corresponding applications are discussed. Based on the Z-scan measurement, the nonlinear refractive index at 800 nm for Si-rich SiNx film is increased from 5.7*10-13 to 9.2*10-12 cm2/W when increasing the excessive Si concentration from 16.3% to 23.4%. Such optical nonlinearity enhancement in the Si-rich SiNx film can be attributed to the strong quantum confinement effect in the Si-QD doped in the SiNx matrix. Then, the FWM has been firstly demonstrated by using the SiNx:Si-QD channel waveguide. The maximum conversion efficiency of -46 dB with the 3-dB bandwidth of 18 nm has been measured in the 8-mm long Si-rich SiNx channel waveguide. Furthermore, the all-optical data modulation in the SiNx based ring resonator has been achieved by using the nonlinear Kerr effect of the Si-QD. The refractive index change induced by the nonlinear Kerr effect is increased from 2*10-5 to 1.6*10-4 for SiNx R0.5 to R0.9 ring resonator under the pump pulse excitation with peak power of 3W. It indicates that the nonlinear refractive index at ~1550 nm are increased from 1.4*10-14 to 1.6*10-13 cm2/W by increasing the excessive Si concentration in SiNx films from 16.3% (R0.5) to 23.4% (R0.9). Finally, the 12 Gbit/s all-optical data conversion and inversion with NRZ-OOK data format has been firstly demonstrated by nonlinear Kerr effect in the SiNx based ring resonator.
Subjects
矽量子點
光波導
量子侷限效應
增強自發輻射
自由載子吸收
四波混頻
非線性克爾效應
Type
thesis
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