GHz Compact Laser Enabled by GaSb Nanowires as Saturable Absorbers

Abstract

Owing to the narrow bandgap and excellent optoelectronic properties, III‐Sb nanowires (NWs) enable efficient optical response from near‐infrared to mid‐infrared, making them ideal candidates for broadband optical modulation. Herein, high‐purity GaSb NWs with controlled density are prepared on the transparent substrates of glasses. The phase purity and crystallinity of as‐prepared GaSb NWs are verified by X‐ray diffraction. Z‐scan and I‐scan techniques are adopted to investigate the nonlinear optical modulation properties, displaying a high modulation depth of 40% (at 1 μm wavelength) for the GaSb NWs with growth time of 30 min. Furthermore, the as‐prepared GaSb NWs are used as the saturable absorber elements in a waveguide laser cavity, demonstrating efficient Q‐switched mode‐locked lasers with a repetition rate of 8.2 GHz and a pulse duration of 31 ps (operating at 1 μm wavelength). All results show the great potential of GaSb NWs for the ultrafast laser and nonlinear optical applications.