A high beam quality, all-solid-state Nd:YAG laser system of high-repetition frequency has been built for Thomson scattering diagnosis. A 1.7 times diffraction limited output beam at a pulse energy of 5 J at 1064 nm is achieved for the first time with a pulse duration of 6.6 ns (FWHM) and a repetition rate of 200 Hz; the output energy stability is 4.9% peak-to-valley over 6000 shots.A novel pulsed laser system (Supplementary Fig. S1) with high average power and high beam quality has recently been built by Dr Zhong-Wei Fan's group at the Academy of Opto-Electronics, Chinese Academy of Sciences. Both the laser diode side-pumped rod and slab crystals are integrated into the amplifier (AMP) system. A 1.7 times diffraction-limited output beam at a pulse energy of 5 J at 1064 nm is achieved for the first time with a pulse duration of 6.6 ns (FWHM) and a repetition rate of 200 Hz; the output energy stability is 4.9% peak-to-valley over 6000 shots. The test results are shown in Figure 1a and 1b.The laser system is constructed in a master oscillator power amplifier (MOPA) configuration, as shown in Figure 1c, with four components: a single-frequency seed laser, pre-amplifier unit, beam control unit, and post-amplifier unit. The pre-amplifier consists of a three-stage, side-pumped rod amplifier. The dimensions of the rod crystals are φ3 mm × 67 mm with a Nd 3+ concentration of 0.8% for AMP1 and AMP2, and φ6.35 mm × 140 mm with a Nd 3+ concentration of 0.6% for AMP3 and AMP4. The techniques of the stimulated Brillouin scattering phase-conjugate mirror (SBS-PCM) and adaptive optics are implemented in the beam control unit to correct the wavefront distortion dynamically. The postamplifier unit is composed of a three-stage, large slab amplifier. The dimensions of the slab crystals are 138 mm (L) × 35 mm (W) × 7 mm (D) with a Nd 3+ concentration of 0.6% for AMP5, AMP6 and AMP7. The single-frequency seed laser produces an output power of 8.58 μJ with a pulse duration of 33.9 ns (FWHM) at a 200-Hz repetition rate. The root-mean-square (RMS) fluctuation in pulse energy is smaller than 1% and the beam quality is better than 1.12 times diffraction limited. The seed pulses first pass through the pre-amplifier and then through the control unit, at which the beam shaping is applied. The pulse energy is amplified to 300 mJ. The pulse duration is 30.5 ns and the beam quality is better than 1.4 times diffraction-limited. After passing through the post-amplifier, the pulse energy reaches 5 J with 3.2 times diffraction limited beam quality. An adaptive optics system is applied for wavefront correction, and the beam quality is improved to 1.7 times diffraction limited.The core parts of the laser system include the single-frequency laser source, slab amplifier module with high-energy storage efficiency, and the phase-conjugated, stimulated Brillouin scattering mirror. The single-frequency source is an active Q-switching laser utilizing acousto-optic modulation. Single-longitudinalmode operation is achieved by applying a Fabry-Pérot (FP) etalo...

In this paper, the design of miniaturized low-pass filter in a Low Temperature Co-fired Ceramic(LTCC) Technology is presented. The pass-band of the low-pass filter is from 900MHz to 1450MHz. The capacitor is constructed by multilayer MIM(Mental-Insulator-Mental) capacitor, and the inductor is fabricated by a narrow metal transmission line. The VSWR of input and output port is less than 1.6. The whole volume of final three-dimension model is 2.0mm 1.25mm 0.90mm.

No abstract