Widely tunable electroabsorption-modulated sampled-grating DBR laser transmitter

TLDR

The study presents a widely tunable transmitter comprising a sampled‑grating DBR laser monolithically integrated with a semiconductor optical amplifier and an electroabsorption modulator. Firmware‑controlled wavelength, power, and mode management provide long‑term stability for system deployment. The module delivers modulated powers above 5 dBm, RF extinction ratios exceeding 10 dB, and error‑free 2.5 Gb/s transmission over 350 km of SMF across a 40‑nm tuning range, while CW operation satisfies long‑haul criteria (stability, >10 mW output, RIN < –140 dB/Hz, linewidth < 2 MHz over 90 50‑GHz ITU channels) and shows median time‑to‑failure over 100 years for wavelength stability and power.

Abstract

We report on a widely tunable transmitter based on a sampled-grating distributed Bragg reflector (SG-DBR) laser monolithically integrated with a semiconductor optical amplifier (SOA) and an electroabsorption (EA) modulator. Modulated time-averaged powers in excess of 5 dBm, RF extinction ratios >10 dB, and error-free transmission at 2.5 Gb/s for 350 km of standard single-mode fiber have been demonstrated across a 40-nm tuning range. In CW mode of operation, the module meets all long-haul system requirements for externally modulated laser sources: stability, power (>10 mW), RIN (<-140 dB/Hz), and linewidth (<2 MHz) over 90 50-GHz spaced ITU channels. Implementation of wavelength, power, and mode control in module firmware ensures long-term stability for system deployment. Systematic investigations of accelerated aging performed on laser tuning and gain sections showed excellent wavelength stability and reliability with median times to failure of >100 yr for output wavelength stability and power across all channels.