Optical nonlinearities in hydrogenated-amorphous silicon waveguides

Abstract

We experimentally measure the optical nonlinearities in hydrogenated-amorphous silicon (a-Si:H) waveguides through the transmission of ultra-short pulses. The measured two-photon absorption coefficient beta is 4.1 cm/GW and we obtain a 3.5pi nonlinear phase shift at 4.1 W coupled input power corresponding to a nonlinear refractive index n(2) of 4.210(-13) cm(2)/W. The measured nonlinear coefficient gamma = 2003 (Wm)(-1) is at least 5 times the value in crystalline silicon. The measured free carrier absorption coefficient sigma = 1.910(-16) cm(2) agrees with the values predicted from the Drude-Lorenz model. It is seen that a-Si:H exhibits enhanced nonlinear properties at 1550 nm and is a promising platform for nonlinear silicon photonics.

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

“…Although initial measurements yielded a FOM no better than c-Si (~0.5) [120,121], more recent results have shown FOMs ranging from 1 [122] to as high as 2 [123,124], allowing very high parametric gain (+26dB) over the C-band [125]. While a key problem for this material has been a lack of stability [126], very recently a-Si nanowires were demonstrated [127] that displayed a combination of high FOM of 5, high n 2 (3-4 times that of crystalline silicon) and good material stability at telecom wavelengths.…”

Emerging heterogeneous integrated photonic platforms on silicon

“…Therefore, only small values of net gain in Raman amplifiers has been observed [115]. Several researchers have totally moved to other nonlinear materials such as hydrogenated amorphous silicon (a-Si:H) [116][117][118], silicon nitride (SiN) [119][120][121], Hydex TM [122,123], chalcogenide glass [124][125][126], and tantalum [131,132]. Table 1 summarizes n 2 and β TPA in all the materials discussed in the previous paragraph in comparison to SiO 2 , as a benchmark.…”

“…Table 1 summarizes n 2 and β TPA in all the materials discussed in the previous paragraph in comparison to SiO 2 , as a benchmark. The literature of a-Si:H is inconsistent and seemingly is very dependent on the deposition condition, but very high values of n 2 have been claimed [116,118]. However, a tradeoff between n 2 and β TPA is observable and overall the considerable value of β TPA (which can be much higher than crystalline Si [116]) limits the FOM (e.g., ∼5 in Ref.…”

Modification of surface properties of bell metal by radiofrequency plasma polymerization

“…In this work, optical fiber has been made form InGaAsP/InP [17][18][19]. The schematic diagram of an optical fiber ring resonator system is shown in Fig.…”