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

Abstract

Silicon nitride Si 3 N 4-on-SiO 2 attracts increasing interest in integrated photonics owing to its low propagation loss and wide transparency window, extending from ∼400 nm to 2350 nm. Scalable integration of active devices such as amplifiers and lasers on the Si 3 N 4 platform will enable applications requiring optical gain and a muchneeded alternative to hybrid integration, which suffers from high cost and lack of high-volume manufacturability. We demonstrate a high-gain optical amplifier in Al 2 O 3 :Er 3 monolithically integrated on the Si 3 N 4 platform using a double photonic layer approach. The device exhibits a net Si 3 N 4-to-Si 3 N 4 gain of 18.1 0.9 dB at 1532 nm, and a broadband gain operation over 70 nm covering wavelengths in the S-, C-and L-bands. This work shows that rare-earth-ion-doped materials and in particular, rare-earth-ion-doped Al 2 O 3 , can provide very high net amplification for the Si 3 N 4 platform, paving the way to the development of different active devices monolithically integrated in this passive platform.

480 Gbps WDM Transmission Through an Al2O3:Er3+ Waveguide Amplifier

“…For a spiral input power of -28 dBm (light saturation region) and -10 dBm (deep saturation region) the total net gain was calculated to 8.5 dB and 6.5 dB respectively. By dividing these values to the 5.9 cm length of the spiral, the results are 1.44 dB/cm and 1.10 dB/cm gain, with similar values reported also from a passive characterization of a similar fabricated chip for a 10 cm long Al2O3:Er 3+ spiral [13]. For these two input powers the net losses of the chip were measured to 22.9 and 24.9 dB, respectively.…”

“…The Al2O3 waveguides were doped with erbium, with a targeted concentration of 1.7×10 20 cm -3 by RF reactive co-sputtering. Vertical adiabatic couplers [20], [13], were utilized to transfer the light from the Si3N4 waveguide to the active Al2O3 spiral and back to the passive Si3N4, inducing 0.5 dB losses per transition according to a reference die with 2-6-12 cascaded structures from the same wafer. In the adiabatic coupler the Si3N4 waveguide is vertically tapered from 200 nm to 30 nm, while the Al2O3 waveguide is horizontally tapered from 1.4 μm to 800 nm.…”

“…The active layer was design for monomode operation at signal and pump wavelength under transverse electric (TE) polarization in agreement with the design optimization of the MMI MUXs/DEMUXs. The length of the Al2O3:Er 3+ spiral was 5.9 cm for this experiment and more details about the fabrication process can be found in [13], [20], [21].…”

On‐Chip Integrated Waveguide Amplifiers on Erbium‐Doped Thin‐Film Lithium Niobate on Insulator

“…The essential advantages of rare‐earth‐ion‐doped materials at longer excited‐state lifetimes and less refractive index changes induced by excitations of doped ions compared to the electron–hole pairs in III–V semiconductors, also boost deep and extensive researches on the photonic integration of erbium‐doped waveguide amplifiers (EDWAs) and lasers with a variety of passive components on a single chip. [ 1 ] An abundance of host materials including crystalline materials like lithium niobate (LiNbO 3 , LN) [ 1 ] and amorphous materials like aluminum oxides (Al 2 O 3 ), [ 2–4 ] tellurium oxide (TeO 2 ), [ 5 ] and tantalum pentoxide (Ta 2 O 5 ), [ 6 ] are widely investigated to provide spatially and temporally stable gain by erbium doping for high‐bit‐rate optical communication and narrow‐linewidth laser source.…”

Poly-crystalline low-loss aluminium oxide waveguides

“…To fulfil the promise of higher data transmission densities and rates at lower energy expenditure by the inclusion of optical links at ever shorter distances such as in board and chip to chip, miniaturized versions of optical fibre components are needed. For erbium doped applications, aluminium oxide (Al2O3) has been shown great promise for the realization of on chip amplifiers 3 and lasers 4 . Integration with both the silicon-on-insulator 5 and silicon sitride 6 platforms has been shown, this last one in a double photonic layer configuration.…”