A 1625 nm Q‐Switched All‐Fiber Laser

Abstract

A Q‐switched all‐fiber Er‐doped laser operated at a wavelength up to 1625 nm is proposed and demonstrated. A self‐developed, element hybridization (Al, Ge, La, P, and Er in the core, Si and P in the cladding region) glass fiber with gain extended to U‐band is employed as gain medium. The compact laser cavity contains a fiber Bragg grating which was manufactured by means of point‐by‐point femtosecond laser inscription technique. Stable Q‐switched laser pulse train is successfully achieved using a semiconductor saturable absorber mirror at a low pump threshold of 29 mW. The laser has a maximum single pulse energy of 746 nJ and a minimum pulse duration of 26.8 μs. The pulse repetition rate can be gradually tuned from 6.47 to 11.87 kHz by increasing the pump power. In particular, the laser wavelength of the Q‐switched all‐fiber laser can be as long as 1625 nm. This is, to the best of our knowledge, the longest wavelength for the Q‐switched Er‐doped fiber lasers at this waveband.