Net optical gain in a low loss silicon-on-insulator waveguide by stimulated Raman scattering

Abstract

We observe for the first time net optical gain in a low loss silicon waveguide in silicon-on-insulator (SOI) based on stimulated Raman scattering with a pulsed pump laser at 1.545 microm. We show that pulsed pumping with a pulse width narrower than the carrier recombination lifetime in SOI significantly reduces the free carrier generation rate due to two-photon absorption (TPA) in silicon. For a 4.8 cm long waveguide with an effective core area of ~1.57 microm2, we obtained a net gain of 2 dB with a pump pulse width of ~17 ns and a peak pump power of ~470 mW inside the waveguide.

A continuous-wave Raman silicon laser

“…Rates of mineral dissolution can be enhanced by biological processes 3 . But plants also take up considerable quantities of silica from soil solution, which is recycled into the soil from falling litter in a separate soil-plant silica cycle that can be significant in comparison with weathering input and hydrologic output [4][5][6][7][8] . Here we analyse soil water in basaltic soils across the Hawaiian islands to assess the relative contributions of weathering and biogenic silica cycling by using the distinct signatures of the two processes in germanium/silicon ratios.…”

“…Recently, stimulated Raman scattering has been used to demonstrate light amplification and lasing in silicon [4][5][6][7][8][9] . However, because of the nonlinear optical loss associated with two-photon absorption (TPA)-induced free carrier absorption (FCA) [10][11][12] , until now lasing has been limited to pulsed operation 8,9 .…”

New CMOS-compatible platforms based on silicon nitride and Hydex for nonlinear optics

“…That issue is the fact that bulk crystalline silicon suffers from high nonlinear absorption due to two-photon absorption (TPA) [23,43] in all telecommunications bands at wavelengths shorter than about 2000 nm. While the effect of TPA generated free carriers can be mitigated by the use of p-i-n junctions to sweep out carriers [44], for example, silicon's intrinsic nonlinear figure of merit (FOM = n 2 /β λ, where β is the TPA coefficient and  the wavelength) is only 0.3 near 1550 nm [45 -47].…”

Compound FDTD method for silicon photonics

“…[6][7][8][9] Nonlinear loss due to FCA is the central problem in silicon devices which operates using nonlinear optical effects. Wavelength converters and Raman amplifier 10,11 are example of such devices. Therefore, sweeping carriers away by introducing a reverse biased p-i-n diode embedded in a silicon waveguide 12 or by nonlinear photovoltaic effect 13,14 can eliminate the loss of FCA.…”