Kilohertz external cavity laser with extended mode-hop-free tuning via thermally self-compensation

Semiconductor lasers offering kilohertz intrinsic linewidths in the C-band are indispensable for space coherent optical communications. However, conventional Fabry-Pérot external-cavity lasers (FP-ECLs) offer only modest mode-hop-free tuning, thereby limiting Doppler shift compensation. Here, we demonstrate a thermally self-compensated FP-ECL achieving a record-wide, mode-hop-free tuning range of 378 pm (47.25 GHz), the broadest reported for C-band FP-ECLs. Throughout this range, it sustains single-longitudinal-mode operation with an intrinsic linewidth below 2 kHz (minimum 436 Hz), an output power of above 20 mW (peak 25 mW), and a long-term wavelength drift of below 0.17 pm over 12 hours without active stabilization. These capabilities meet the stringent requirements of next-generation satellite coherent payloads, demanding wide tunability, spectral purity, and vibration-tolerant stability.