Abstract: A low-level light detector includes an avalanche photodiode (APD) to which is applied a bias voltage adjusted to produce a multiplication factor of not more than 30, and a capacitor for accumulating carriers produced by light in the APD and multiplied using the APD characteristics, the capacitor being connected to the avalanche photodiode. The detector detects the intensity of light impinging on the avalanche photodiode by periodically reading the capacitor voltage and obtaining time-based differences in the voltage, or by resetting the capacitor voltage to a predetermined voltage each time the capacitor voltage is read.

Abstract: A laser device using two laser media includes an excitation light source, a first laser oscillator having a first solid-state laser medium excited by the excitation light source, a second solid-state laser medium disposed in the first laser oscillator and excited by light from the first solid-state laser medium and an output device for emitting light amplified by the second solid-state laser medium.

Abstract: A device that accepts input of asynchronously-arriving variable-length optical packets transmitted over a plurality of lightpaths, and outputs same to a single optical path, comprising: in order to prevent the optical packets from overlapping in the output lightpath, a controller that uses the delay times of the delay elements and the optical packet length and arrival gap time thus read to determine by computation the delay element used for temporary storage, where a plurality of stages of processors is provided. Thus, the processing required to determine the delay time is performed by parallel processing with the results of processing the prefix-sum operation used in parallel pipelined processing along with the queue length, optical packet length and arrival gap time of the buffering device.