[en] The laser pulse waveform real-time precision measurement technology based on time division multiplexing (TDM) was developed for all fiber multi-beam high repetition frequency laser system. According to the characteristic of the system, we designed a kind of 1 × 8 optical time division multiplexer and a kind of 1×2 optical time division multiplexer with different time delay. Also we experimentally demonstrated the technology in the system, the results show that the pulse duration, pulse energy and rise time could be accurately measured, and meanwhile the system working status could be inspected in real time. (authors)

[en] In this paper we propose an efficient off-axis multi-pass Nd:glass amplifier with a birefringence crystal. By utilizing the optical principle of birefringence crystals and the angle differences of the input–output laser directions in a typical off-axis amplifier, the amplification-pass was extended from four-pass to eight-pass without increasing the off-axis angle. The detailed principles and amplifier parameter design are presented. Using the proposed off-axis eight-pass amplifier, a 1 Hz repetitive Nd:glass amplifier at several joules was experimentally demonstrated. A total transmission of 54% was achieved. At an input energy of 1.5 mJ and small-signal gain of 3.6, the output energy and the corresponding net gain were 2.5 J and 1667, respectively. The beam quality was good. The spatial intensity modulation index for 90% beam aperture was 1.29 and the 95% energy concentration of far field patterns was 2.77 times the diffraction limit. (paper)

[en] The frequency modulation to amplitude modulation (FM-to-AM) effect is one of the few remaining scientific issues in a large-scale laser facility which could prevent fusion ignition. A fiber-based polarization–rotation filter which consists of a fiber polarizer, a section of polarization-maintaining fiber, a half-wave plate and a polarization beam splitter is proposed to suppress the FM-to-AM effect. Theoretical analysis and experimental demonstration in the preamplifier module of the SG-III laser facility prove the effectiveness of this filter. (paper)

[en] Time division multiplexing technique was employed and a high repetition frequency of 160 MHz was obtained based on a mode-locked fiber laser with a repetition frequency of 80 MHz. Meanwhile, a high repetition frequency short pulse fiber laser system with an output average power of 105 W, a pulse duration of 12.4 ps and a repetition frequency of 160 MHz was presented experimentally and theoretically employed by large mode area fiber amplifier technique. (authors)