Q-Switched Erbium-Doped Fiber Laser Using Cadmium Selenide Coated onto Side-Polished D-Shape Fiber as Saturable Absorber

A stable Q-switched erbium doped fiber laser emitting at 1558 nm is demonstrated using a cadmium selenide (CdSe) material coated onto a side-polished D-shape fiber as the saturable absorber (SA). By elevating the input pump power from the threshold of 91 mW to the maximum available power of 136 mW, a pulse train with a maximum repetition rate of 57.44 kHz, minimum pulse width of 3.76 μs, maximum average output power of 7.99 mW, maximum pulse energy of 0.1391 \muJ, and maximum peak power of 36.99 mW are obtained. The signal-to-noise ratio of the spectrum is measured to be around 75 dB. This CdSe based SA is simple, robust, and reliable, and thus suitable for making a portable pulse laser source.