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.

A hybrid structure gaseous detector for ion backflow suppression

A new concept for a hybrid structure gaseous detector module with ion backflow suppression for the time projection chamber in a future circular collider is presented.It is a hybrid structure cascaded Gas Electron Multiplier（GEM） with a Micromegas detector.Both Micromegas and GEM have the capability to naturally reduce most of the ions produced in the amplification region.The GEM also acts as the preamplifer device and increases gas gain together with the Micromegas.Feasibility tests of the hybrid detector are performed using an ^（55）Fe X-ray source.The energy resolution is better than 27% for 5.9 keV X-rays.It is demonstrated that a backflow ratio better than 0.2% can be reached in the hybrid readout structure at a gain of 5000.