The response characteristics of avalanche photodiodes to ultrashort pulsed laser

• Theoretical model of APD response to ultrashort pulse is established.
• Response of APD to different pulse width, laser power and energy is investigated.
• Pulse width of an ultrashort pulse cannot be responded by conventional APD.
• Peak response voltages rise with the increase of laser power or pulse width.

The physical model of avalanche photodiode (APD) response to ultrashort pulsed laser is established. Numerical simulation of APD response characteristics is focused and presented. The simulated results show that the response peak voltage degrades approximately linearly with the laser pulse duration narrowing when the peak power of laser pulse keeps unchanged. Meanwhile, when the energy of input pulse laser is at the same quantity, the response peak voltage keeps invariably in different pulse duration. Moreover, the pulse duration of response voltage is determined by the sensitivity of APD itself, and the input duration of ultrashort pulsed laser could not be recognized by the APD. Experiments are carried out and the experimental results are in good agreement with simulated data.