Abstract: A system 200 for altering laser pulse duration includes a chirped fiber Bragg grating (cFBG) 122, a Faraday rotator 230, a retroreflector 240, and a fiber-optic polarization combiner 210 coupled to the chirped fiber Bragg grating 122 via the Faraday rotator 230. The combiner 210 directs a laser pulse via the Faraday rotator 230 to a first reflection in the cFBG 122, then directs the laser pulse to the retroreflector 240, then directs the laser pulse via the Faraday rotator 230 to a second reflection in the cFBG 122, and then emits the laser pulse. A three-port fiber-optic circulator 250 may serve as an input/output interface. Another system for altering laser pulse duration includes a cFBG 122, a fiber-optic polarization combiner 210 coupled to the cFBG 122, and a four-port fiber-optic circulator 550 coupled to the combiner 210 to direct a laser pulse from through the combiner 210 to the cFBG 210 via two different paths. These systems passively achieve two passes through the same cFBG 210.