Design of low-noise photodetector with a bandwidth of130 MHz based on transimpedance amplification circuit

A low-noise photodetector is a basic tool for the research of quantum information processing. We present a specially designed low-noise photoelectric detector with a bandwidth of 130 MHz, using a transimpedance amplification circuit. Based on the detailed calculation of the dependence on each parameter of the detector,a useful method of how to design a low-noise and broadband photodetector is provided. When the optical power is between 1.0 and 16 m W, the photodetector has a good linear response to the injected light. Its electronics noise power is below-77 d Bm, which is within the whole bandwidth. When the incident light power is 2 m W, the output noise powers are 10.0, 8.0, and 6.0 d B higher than the corresponding electronics noise within the bandwidth of 1–50, 50–90, and 90–130 MHz, respectively, which is in good agreement with the theoretical prediction.Thus, this photoelectric detector could have good application prospects in quantum communication and an optical cavity locking system.

255 W picosecond MOPA laser based on self-made Yb-doped very-large-mode-area photonic crystal fiber

We report on the amplification of high-average-power and high-efficiency picosecond pulses in a self-made verylarge-mode-area Yb-doped photonic crystal fiber（PCF）. The PCF with a core diameter of 105 μm and a core numerical aperture of 0.05 is prepared by the sol-gel method combined with the powder sintering technique. The fiber amplification system produces the highest average power of 255 W at a 10 MHz repetition rate with a 21 ps pulse duration corresponding to a peak power of 1.2 MW. This result exemplifies the high-average-power and high-peak-power potential of this specifically designed fiber.