High-power tunable low-noise coherent source at 106 μm based on a surface-emitting semiconductor laser

Abstract

Exploiting III-V semiconductor technologies, vertical external-cavity surface-emitting laser (VECSEL) technology has been identified for years as a good candidate to develop lasers with high power, large coherence, and broad tunability. Combined with fiber amplification technology, tunable single-frequency lasers can be flexibly boosted to a power level of several tens of watts. Here, we demonstrate a high-power, single-frequency, and broadly tunable laser based on VECSEL technology. This device emits in the near-infrared around 1.06 mu m and exhibits high output power (> 100 mW) with a low-divergence diffraction-limited TEM00 beam. It also features a narrow free-running linewidth of < 400 kHz with high spectral purity ( side mode suppression ratio > 55 dB) and continuous broadband tunability greater than 250 GHz (< 15 V piezo voltage, 6 kHz cutoff frequency) with a total tunable range up to 3 THz. In addition, a compact design without any movable intracavity elements offers a robust single-frequency regime. Through fiber amplification, a tunable single-frequency laser is achieved at an output power of 50 W covering the wavelength range from 1057 to 1066 nm. Excess intensity noise brought on by the amplification stage is in good agreement with a theoretical model. A low relative intensity noise value of - 145 dBc/Hz is obtained at 1 MHz, and we reach the shot-noise limit above 200 MHz. (C) 2018 Optical Society of America