A single-frequency pulsed all-fiber laser with a master oscillator power amplifier configuration is presented.While maintaining the properties of single mode,linear polarization,and narrow linewidth,a single-pulse energy of 260 μJ and over 500-W peak power is experimentally demonstrated at 1 kHz by employing tensile strain gradient and pulse-shape control methods.In addition,approximately 55 dB of optical signal to noise ratio is also achieved.