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.

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In this work, we present on optical gain and lasing in an ultra-compact thulium-silicon hybrid microdisk resonator emits around 1.9 µm with an internal slope efficiency of 60% and > 1 mW on-chip output power.

Silicon photonics is an ideal platform for low-cost, energy-efficient, and high-performance optical microsystems. However, because silicon is an inefficient light emitting material, the development of simple, inexpensive, and scalable monolithic amplifiers and light sources has been a significant challenge. Here, optical gain and lasing in an ultra-compact hybrid rare-earth silicon microdisk resonator are reported. The microdisk design is straightforward and compatible with the fabrication steps and device dimensions available in all silicon photonics foundries, while the thulium-doped tellurite gain medium is added in a low-temperature single-step sputter deposition. This approach allows for low-cost and high-volume wafer-scale manufacturing and co-integration of rare-earth amplifiers and light sources with silicon passive and active devices with no adjustment to standard process flows. The hybrid laser is pumped at standard telecom wavelengths around 1.6 µm and exhibits stable single-mode emission at 1.9 µm, with an internal slope efficiency of 60% and >1 mW on-chip output power. The laser is highly promising for emerging communications and sensing applications and opens new possibilities for the development of monolithic rare-earth optical amplifiers and lasers directly on silicon.

We report on the fabrication and optical characterization of erbium-ytterbium co-doped aluminum oxide (Al2O3:Er3+:Yb3+) waveguides using low-cost, low-temperature deposition and etching steps. We deposited Al2O3:Er3+:Yb3+ films using reactive co-sputtering, with Er3+ and Yb3+ ion concentrations ranging from 1.4–1.6 × 1020 and 0.9–2.1 × 1020 ions/cm3, respectively. We etched ridge waveguides in 85% pure phosphoric acid at 60°C, allowing for structures with minimal polarization sensitivity and acceptable bend radius suitable for optical amplifiers and avoiding alternative etching chemistries which use hazardous gases. Scanning-electron-microscopy (SEM) and profilometry were used to assess the etch depth, sidewall roughness, and facet profile of the waveguides. The Al2O3:Er3+:Yb3+ films exhibit a background loss as low as 0.2 ± 0.1 dB/cm and the waveguide loss after structuring is determined to be 0.5 ± 0.3 dB/cm at 1640 nm. Internal net gain of 4.3 ± 0.9 dB is demonstrated at 1533 nm for a 3.0 cm long waveguide when pumped at 970 nm. The material system is promising moving forward for compact Er-Yb co-doped waveguide amplifiers and lasers on a low-cost silicon wafer-scale platform.

We report on low-temperature and low-pressure deposition conditions of 140 °C and 1.5 mTorr, respectively, to achieve high-optical quality silicon nitride thin films. We deposit the silicon nitride films using an electron cyclotron resonance plasma-enhanced chemical vapour deposition (ECR-PECVD) chamber with Ar-diluted SiH4, and N2 gas. Variable-angle spectroscopic ellipsometry was used to determine the thickness and refractive index of the silicon nitride films, which ranged from 300 to 650 nm and 1.8 to 2.1 at 638 nm, respectively. We used Rutherford backscattering spectrometry to determine the chemical composition of the films, including oxygen contamination, and elastic recoil detection to characterize the removal of hydrogen after annealing. The as-deposited films are found to have variable relative silicon and nitrogen compositions with significant oxygen content and hydrogen incorporation of 10–20 and 17–21%, respectively. Atomic force microscopy measurements show a decrease in root mean square roughness after annealing for a variety of films. Prism coupling measurements show losses as low as 1.3, 0.3 and 1.5 ± 0.1 dB/cm at 638, 980 and 1550 nm, respectively, without the need for post-process annealing. Based on this study, we find that the as-deposited ECR-PECVD SiOxNy:Hz films have a suitable thickness, refractive index and optical loss for their use in visible and near-infrared integrated photonic devices.

We demonstrate 5 dB of net gain at 1558 nm in a 6.7 cm long erbium-doped tellurium- oxide-coated silicon nitride waveguide, in a process compatible with silicon nitride photonic integrated circuits.

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