A Q-switched all-fiber laser utilizes a long period fiber grating (LPFG) modulator. The LPFG modulator is characterized by optical spectral characteristics that are controlled by application of stress via an actuator. In particular, the actuator applies stress to selected sections of the LPFG in order to modulate a light signal at a specified wavelength. Further, a controller is utilized to control the application of stress in the time domain, and thereby switch the Q-factor of the fiber laser cavity. In addition to the LPFG, the laser cavity comprises a pair of fiber Bragg gratings (FBGs) and a fiber gain medium.