14:45 〜 15:00
▲ [13p-2S-5] Observation of Raman Scattering in a silicon photonics crystal waveguide with p-i-n diode structure
キーワード：Raman scattering,Photonics crystal,Free carrier absorption
Raman scattering effect enables bulk silicon to generate coherent light. Photonics crystal (PhC) is one of promising structures to enhance Raman scattering and reduce the device size. Ultra-compact Raman laser with low threshold power has been demonstrated using a PhC nanocavity[1]. PhC waveguide is also attractive for Raman amplification using the slow light effect. Stimulated Raman scattering in PhC waveguides has been also observed [2,3]. However, at high pump powers, free carrier absorption (FCA) associated with two photon absorption (TPA) is a crucial obstacle for achieving the amplification. Adding a reverse bias through a p-i-n junction is known as an effective way to suppress the FCA effect [4]. Nevertheless, to date there is no report on Raman scattering in a silicon PhC WG with p-i-n diode structure. Here, we report the observation of Raman Stokes signal in silica-cladded Si PhC WGs with p-i-n structure.
An SEM image of the PhC WG used here shown in Fig. 1(a). A p-i-n junction was formed across the waveguide. Electrodes (not shown) were deposited to provide reverse bias through the junction. Figure 1 (b) shows the transmission spectra for both TE- and TM- polarizations of a sample with the i-region width of 0 mm. We utilized the band edge of the TE-like waveguide mode for pump and the fundamental index-guided TM-like mode for Stokes wave. Calculated field distributions of the TE- and TM-like modes are shown in Fig. 1 (c) and (d), respectively. I-V curves with various input pump powers (Fig. 2(a)) indicate that photo-excited carriers, which cause the FCA loss, are swept away from the waveguide region. Figure 2(b) shows the Stokes signal power as a function of pump power for various configurations. Compared to the Stokes signal in open-circuit condition, Stokes signals are improved in short-circuit and reverse-biased (-4V) conditions. Details will be discussed in the presentation
An SEM image of the PhC WG used here shown in Fig. 1(a). A p-i-n junction was formed across the waveguide. Electrodes (not shown) were deposited to provide reverse bias through the junction. Figure 1 (b) shows the transmission spectra for both TE- and TM- polarizations of a sample with the i-region width of 0 mm. We utilized the band edge of the TE-like waveguide mode for pump and the fundamental index-guided TM-like mode for Stokes wave. Calculated field distributions of the TE- and TM-like modes are shown in Fig. 1 (c) and (d), respectively. I-V curves with various input pump powers (Fig. 2(a)) indicate that photo-excited carriers, which cause the FCA loss, are swept away from the waveguide region. Figure 2(b) shows the Stokes signal power as a function of pump power for various configurations. Compared to the Stokes signal in open-circuit condition, Stokes signals are improved in short-circuit and reverse-biased (-4V) conditions. Details will be discussed in the presentation