Development of New Types of Linear Photo Detectors

点击翻译按钮获取中文摘要

We have built a test setup to measure the linearity with the precision of 0.1%. By using the system, we have evaluated the linearity of the following new types of photo detectors.*Avalanche type photo diodeA bias voltage of about 1500V-2400V is applied on an avalanche photo diode (APD). A photon entering the p-type silicon forms an electron-hole pair. The electron is accelerated by the voltage, and produce another pairs, thereby amplifies the signal. The nonlinearity at the gain of 200 was less than 0.1% up to 140 thousand incident photons.*Hybrid type photomultiplier with Si diodeThis detector consists of cathode and PIN diode, and a voltage of about 10kV is applied between them. Photoelectrons from the cathode is accelerated, and produce about 2500 electorons per photoelectron when they hit the diode. The signal is detected by the PIN diode. This detector has an excellent linearity because of simple electron trajectory, and the good linearity of the PIN diode. The measured non-linearity was less than 0.1% up to 140 thousand incident photons.*Hybrid type photomultiplier with avalanche type Si diodeThis detector is same as the above except that it uses APD instead of PIN diode, to obtain higher gain. The measured non-linearity was about 6% at the gain of 5000, for 14 thousand incident photons. This large non-linearity was due to the avalanche photo diode itself, and it should in principle be more linear with a better APD.