Erbium-doped TeO₂-coated Si₃N₄ waveguide amplifiers with 5  dB net gain

Abstract

We demonstrate 5 dB net gain in an erbium-doped tellurium-oxide-coated silicon nitride waveguide. The amplifier design leverages the high refractive index and high gain in erbium-doped tellurite glass as well as the ultra-low losses and mature, reliable, and low-cost fabrication methods of silicon nitride waveguide technology. We show that the waveguide platform demonstrates low background propagation losses of 0.25 dB/cm based on a ring resonator device with a Q factor of 1.3 × 10 6 at 1640 nm. We measure 5 dB peak net gain at 1558 nm and > 3 dB of net gain across the C band in a 6.7 cm long waveguide for 35 mW of launched 1470 nm pump power. Gain per unit length of 1.7 and 1.4 dB/cm is measured in a 2.2 cm long waveguide for 970 and 1470 nm pump wavelengths, respectively. Amplifier simulations predict that > 10 dB gain can be achieved across the C band simply by optimizing waveguide length and fiber-chip coupling. These results demonstrate a promising approach for the monolithic integration of compact erbium-doped waveguide amplifiers on silicon nitride chips and within silicon-based photonic integrated circuits.

High-gain waveguide amplifiers in Si3N4 technology via double-layer monolithic integration

“…Amorphous host materials can typically be deposited at the wafer level leading to simpler fabrication and integration schemes. Several host materials have been demonstrated, including Ta 2 O 5 doped with both Er 3 and Yb 3 [30], TeO 2 doped with Er 3 [31] and Tm 3 [32], and Al 2 O 3 doped with Nd 3 , Yb 3 , Er 3 , Tm 3 , and Ho 3 [19,25,[33][34][35] to achieve emission at different wavelengths. Those materials are mainly deposited by reactive co-sputtering, although recent studies on rare-earth-ion-doped Al 2 O 3 deposited by atomic layer deposition have shown very high gain per unit length (i.e., 20.1 7.31 dB∕cm net modal gain in Al 2 O 3 :Er 3 ) [23] thanks to the control of Al 2 O 3 and Er 2 O 3 at the sub-atomic level.…”

“…In this work, we present an integrated high total gain (i.e., from passive waveguide to passive waveguide) optical amplifier in Al 2 O 3 :Er 3 monolithically integrated onto the Si 3 N 4 platform via a double-layer platform [38]. Different from previous integration methodologies in which the Al 2 O 3 :RE 3 material was directly deposited onto Si 3 N 4 elements [20,21,23,31] or sputtered into SiO 2 trenches within the Si 3 N 4 platform [19,22], in our approach the Al 2 O 3 :RE 3 and the Si 3 N 4 waveguides are located in two individual layers separated by a thin SiO 2 film. The optical modes are therefore guided independently in each of the photonic layers permitting their independent optimization to minimize losses and to maximize the overlap between pump and signal modes on the active waveguides.…”

Nonlinear silicon photonics on CMOS-compatible tellurium oxide

“…Such a device not only is useful as a stand-alone highly nonlinear system but can also enhance the nonlinearity of the existing Si 3 N 4 waveguides postfabrication. Together with the emerging integrated lasers and amplifiers on TeO 2 and other rare-earth media [47][48][49]24,25], this work paves the way for a monolithic TeO 2 -based nonlinear silicon photonics platform.…”

Erbium-doped hybrid waveguide amplifiers with net optical gain on a fully industrial 300 mm silicon nitride photonic platform

“…To optimize the performance of erbium-based integrated amplifier devices, various host materials and different fabrication methods have been studied to achieve high erbium-incorporation inside different compounds [7][8][9][10][11][12][13][14][15][16][17][18][19]. Additionally, unique waveguide geometries have also been proposed to maximize the interaction of the guided beams with the active layer [20][21][22][23][24][25]. Despite the recent progress in the field, there is still a relatively long way to go before erbium-based integrated devices can be established as fundamental active building blocks in the silicon photonics industry.…”