Mid-infrared optical parametric amplifier using silicon nanophotonic waveguides

Abstract

All-optical signal processing is envisioned as an approach to dramatically decrease power consumption and speed up performance of next-generation optical telecommunications networks 1-3 . Nonlinear optical effects, such as four-wave mixing (FWM) and parametric gain, have long been explored to realize all-optical functions in glass fibers 4 . An alternative approach is to employ nanoscale engineering of silicon waveguides to enhance the optical nonlinearities by up to five orders of magnitude 5 , enabling integrated chip-scale all-optical signal processing.FWM within silicon nanophotonic waveguides has recently been used to demonstrate several telecom-band (λ~1550nm) all-optical functions, including wavelength conversion 6-9 , signal regeneration 10 , and tunable optical delay 11 . Despite these important advances, strong two-photon absorption 12 (TPA) of the telecom-band pump has been a fundamental and unavoidable obstacle, limiting parametric gain to values on the order of a few dB 13 . Here we demonstrate a silicon nanophotonic optical parametric amplifier exhibiting gain as large as 25.4 dB, by operating the pump in the mid-IR near one-half the band-gap energy (E~0.55eV, λ~2200nm), at which parasitic TPA-related absorption vanishes 12,14 . This gain is high enough to compensate all insertion losses, resulting in 13 dB net off-chip amplification. Furthermore, dispersion engineering 15 dramatically increases the gain bandwidth to more than 220 nm, all realized using an ultra-compact 4 mm silicon chip. Beyond its significant relevance to all-optical signal processing, the broadband parametric gain also facilitates the simultaneous generation of

Nonlinear silicon nanophotonics for mid-infrared applications

“…Moreover, a frequency up-shifted Raman anti-Stokes [15] peak at a wavelength of 1950 nm is visible. The visibility here of a strong MI background suggests that the on-chip mid-IR parametric gain available is far larger than demonstrated in previous studies [1], where MI was not observed. As illustrated in Fig.…”

“…Moreover, we demonstrate that on-chip gain can exceed 50 dB in narrow bands assisted by stimulated Raman scattering. In comparison with prior work [1], the peak operating pump power is reduced to less than half. At the same time, the maximum on-chip gain obtained using the 2 cm-long wire here shows an improvement of more than 25 dB, while the on-chip gain bandwidth (> 580 nm) is increased by more than 2.5x.…”

“…We have recently demonstrated the first silicon photonic wire mid-IR optical parametric amplifier (OPA) [1]. The OPA exhibits net off-chip gain of 13 dB in addition to on-chip gain as large as 25.4 dB (Fig.…”

“…Within the mid-infrared (mid-IR) spectral region near λ = 2200 nm, the silicon nanophotonic wire platform has potential to be used in constructing room temperature, highly efficient, ultra-compact devices for light generation and amplification through coherent nonlinear optical processes [1][2][3]. This platform could be an ideal host for a variety of mid-IR applications including molecular spectroscopy, free-space communication and environmental monitoring [4,5].…”

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

“…The fact that many impressive all-optical demonstrations have been made in silicon despite its low FOM is a testament to how exceptional its linear and nonlinear optical properties are. Nonetheless, the critical impact of silicon's large TPA was illustrated [48,49] in 2010 by the demonstration of high parametric gain at wavelengths beyond 2 µm, where TPA vanishes. Indeed, it is likely that in the midinfrared wavelength range where it is transparent to both one photon and two photon transitions -between 2 and 6 µm -silicon will undoubtedly remain a highly attractive platform for nonlinear photonics.…”