LAUSR

Nanoscale laser sources with downscaled device footprint, high energy efficiency and operation speed are pivotal for a wide array of opto-electronic and nanophotonic applications ranging from on-chip interconnects, nano-spectroscopy, sensing to optical communication. The capability of on-demand lasing output with reversible and continuous wavelength tunability over broad spectral range enables key functionalities in wavelength-division multiplexing (WDM) and finely controlled light-matter interaction, which remains an important subject under intense research. In this study, we demonstrate an electrically controlled wavelength-tunable laser based on CdS nanoribbon (NR) structure. Typical 'S'-shaped characteristics of pump power dependence was observed for dominant lasing lines, with concomitant line width narrowing. By applying an increased bias voltage across the NR device, the lasing resonance exhibits a continuous tuning from 510 nm to 520 nm for a bias field ranged within 0 kV/cm - 15.4 kV/cm. Systematic bias-dependent absorption and time-resolved photoluminescence (PL) measurements were performed, revealing a red-shifted band edge of gain medium and prolonged PL lifetime with increased electric field over the device. Both current-induced thermal reduction of band gap and Franz-Keldysh effect were identified to account for the modification of lasing profile, with the former factor playing the leading role. Furthermore, dynamical switching of NR lasing was successfully demonstrated, yielding a modulation ratio up to ~ 21 dB. The electrically tuned wavelength-reversible CdS NR laser in this work, therefore, presents an important step towards color-selective coherent emitters for future chip-based nano-photonic and opto-electronic circuitry.