RESUMEN
In silicon devices, the spectral bandwidth of coherent anti-Stokes Raman scattering (CARS) is limited by the narrowband nature of the Raman process in this medium. In this Letter, we report the observation of broadband wavelength conversion in silicon through CARS enhanced by the self-phase-modulation-induced spectral broadening of the optical pump. The CARS conversion over a bandwidth substantially greater than the intrinsic Raman linewidth is demonstrated yielding conversion efficiencies as high as 1%. Numerical simulations are performed to explain the spectral features observed in the spectrum of the anti-Stokes signal.
RESUMEN
Three-dimensionally (3-D) integrated photonic structures in multiple layers of silicon are reported. Implantation of oxygen ions into a silicon-on-insulator substrate with a patterned thermal oxide mask, followed by a high temperature anneal, creates photonic structures on 3-D integrated layers of silicon. This process is combined with epitaxial growth to achieve devices on three vertically integrated layers of silicon. As a demonstration vehicle, we report a multistage optical filter that comprises of coupled microdisks on two subsurface silicon layers with bus waveguides on the surface (3rd) layer. The optical filter shows extinction ratios in excess of 14 dB, with excess insertion loss of less than 1 dB.
RESUMEN
We describe the first observation of spontaneous Raman emission, stimulated amplification, and lasing in a SiGe waveguide. A pulsed optical gain of 16dB and a lasing threshold of 25 W peak pulse power (20 mW average) is observed for a Si1-xGex waveguide with x=7.5%. At the same time, a 40 GHz frequency downshift is observed in the Raman spectrum compared to that of a silicon waveguide. The spectral shift can be attributed to the combination of composition- and strain-induced shift in the optical phonon frequency. The prospect of Germanium-Silicon-on-Oxide as a flexible Raman medium is discussed.
RESUMEN
First demonstration of cross phase modulation based interferometric switch is presented in silicon on insulator waveguides. By using Mach-Zehnder interferometric configuration we experimentally demonstrate switching of CW signal ~25 nm away from the pump laser. We present the effect of free carrier accumulation on switching. Additionally, we theoretically analyze the transient effects and degradations due to free carrier absorption, free carrier refraction and two photon absorption effects. Results suggest that at low peak power levels the system is governed by Kerr nonlinearities. As the input power levels increase the free carrier effects becomes dominant. Effect of free carrier generation on continuum generation and power transfer also theoretically analyzed and spectral broadening factor for high input power levels is estimated.