![]() When used with a 1xN cyclic demux or wavelength de-interleaver to create a parallel multi-wavelength transmitter with Nx25 GHz spacing, it becomes possible to use a single comb source and extend the bandwidth per wavelength to be side-band crosstalk-limited by the de-interleaved wavelength spacing of the comb for non-return-to-zero or multi-level amplitude modulation 28, 29, or OSNR-limited for coherent communication 30. Stable far-field output angles of 5°–7° and 27° in the slow- and fast-axes respectively, enable polarization-maintaining fiber-coupling efficiencies of approximately 75% of peak power after assembly into butterfly packages. At 25 GHz wavelength spacing, the O-band comb lasers achieve stable, CW performance across an operating bandwidth over 2 THz, Lorentzian linewidths of 140–170 kHz, peak PCE over 30% ex-facet at 25 ☌ at 200 mA drive current, and ex-facet power above 250 mW at 500 mA drive current (Fig. Here we show that passively mode-locked quantum-dot comb lasers with wavelength spacings in the range of 25–100 GHz can be operated the individual modes being phase correlated and exhibit excellent output power, efficiency, uniformity and spectral properties. However, a continuing challenge for comb lasers for short-distance communication and computing applications has been to concurrently achieve adequate power per line, uniform output power over a wide spectral range, low noise per line, narrow linewidth, and notably high energy efficiency-a key requirement for optics in computing systems 27. Passively mode-locked quantum-dot comb lasers 21, 22 together with silicon microring modulators have been investigated for optical interconnects with promising results 23, 24, 25, 26. Driven by applications in sensing, metrology, and optical communications, we have witnessed renewed interest in integrated, pulsed semiconductor mode-locked lasers 19, 20. Fabry–Perot lasers based on self-assembled InAs quantum dots grown on GaAs substrates demonstrated early potential for lasing over as many as 1000 wavelengths across 14 THz 18. Inspired by the promise of three-dimensional confinement of carriers 12, early work on room temperature quantum dot lasers showed potential for very low threshold currents 13, 14, 15, O-band operation 16, 45% power conversion efficiency (PCE) and up to 3.5 W of continuous-wave (CW) power 17. But an energy-efficient, reliable, high-power, scalable-wavelength comb source has proved elusive. Resonant silicon microring modulators, when cascaded on a waveguide bus, have demonstrated the ability for dense WDM links with bandwidth and energy-efficiency in the low picojoules/bit 7, 8, 9, 10, 11. A number of low-voltage, high-speed modulator array technologies, including silicon microring modulators 1, 2, 3, 4, 5 and lithium niobate on insulator modulators 6, have been developed to meet this challenge. The unabated growth in datacenter compute and switching bandwidth has driven an ever-increasing demand for reliable, energy-efficient and cost-effective optical interconnect.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |