Ultra-narrow-linewidth Al2O3:Er3 lasers with a wavelength-insensitive waveguide design on a wafer-scale silicon nitride platform
Optical Society of America (OSA)
Reason for embargo
Under indefinite embargo due to publisher policy.
We report ultra-narrow-linewidth erbium-doped aluminum oxide (Al2O3:Er3+) distributed feedback (DFB) lasers with a wavelength-insensitive silicon-compatible waveguide design. The waveguide consists of five silicon nitride (SiNx) segments buried under silicon dioxide (SiO2) with a layer Al2O3:Er3+ deposited on top. This design has a high confinement factor (> 85%) and a near perfect (> 98%) intensity overlap for an octave-spanning range across near infra-red wavelengths (950–2000 nm). We compare the performance of DFB lasers in discrete quarter phase shifted (QPS) cavity and distributed phase shifted (DPS) cavity. Using QPS-DFB configuration, we obtain maximum output powers of 0.41 mW, 0.76 mW, and 0.47 mW at widely spaced wavelengths within both the C and L bands of the erbium gain spectrum (1536 nm, 1566 nm, and 1596 nm). In a DPS cavity, we achieve an order of magnitude improvement in maximum output power (5.43 mW) and a side mode suppression ratio (SMSR) of > 59.4 dB at an emission wavelength of 1565 nm. We observe an ultra-narrow linewidth of ΔνDPS = 5.3 ± 0.3 kHz for the DPS-DFB laser, as compared to ΔνQPS = 30.4 ± 1.1 kHz for the QPS-DFB laser, measured by a recirculating self-heterodyne delayed interferometer (R-SHDI).
Defense Advanced Research Projects Agency (DARPA) E-PHI (grant no. HR0011-12-2-0007) project.
This is the author accepted manuscript. The final version is freely available on open access from Optical Society of America via the DOI in this record.
Vol. 25, Issue 12, pp. 13705-13713