Broadband parametric amplification in AlGaAs-on-insulator nanowaveguides

Abstract

Optical amplification is critical for optical signal transmission. While the emergence of erbium-doped fiber amplifiers has revolutionized optical communications in fiber-based systems, on-chip amplification remains essential for integrated optics. Nanoscale waveguides enhance nonlinearity by several orders of magnitude, making them promising candidates for optical parametric amplification. Using a pulsed pump at 1550 nm, broadband optical parametric amplification based on four-wave mixing is investigated in AlGaAs-on-insulator nanowaveguides. The strong nonlinearity enables an on-off gain as high as 58.4 dB. Meanwhile, the low propagation loss leads to a net on-chip gain of 56.2 dB. With further dispersion engineering, the net on-chip gain bandwidth extends beyond 415 nm, which is 2.3 times larger than previous reports pumped in the telecom band in integrated optics. These results represent the largest parametric gain and bandwidth reported for on-chip parametric amplifiers.

Figures (5)

• Figure 1: Nonlinear photonic chip for optical parametric amplification. (a) Schematic illustration of FWM-based parametric amplification. (b) Experimental setup of FWM-based parametric amplification. EDFA: erbium-doped fiber amplifier; WSS: wavelength selective switch; PC: polarization controller; VOA: variable optical attenuator; OSA: optical spectrum analyzer. (c) SEM picture of an AlGaAsOI nano-waveguide. The thin ridge cladding on top corresponds to the residual hydrogen silsesquioxane (HSQ) resist remaining after the etching process, originally used as a hard mask. (d) Dispersion of waveguides with different cross-sections.
• Figure 2: Spectra and net on-chip gain for optical parametric amplification. (a) Spectra with the signal on and off, and the input pump spectrum. (b) Net on-chip signal parametric gain (red circles) and idler translation gain (blue triangles).
• Figure 3: Performance characteristics of optical parametric amplification. (a) Output peak power of signal and idler pulses versus input signal power. (b) Net on-chip parametric and translation gain versus the peak power of the input pump pulse.
• Figure 4: Optical parametric amplification for the waveguide with a $630\times290$ nm cross section.
• Figure 5: Net on-chip gain bandwidth of integrated optical parametric amplifiers pumped in the telecom band. Red line: pump wavelength; blue region: reported spectral range where net on-chip gain is positive. The E-, S-, C-, L-, and U-bands are all WDM channels.