The optical detector used in pulsed LIDAR, range finding and optical time domain reflectometry systems is typically the limiting factor in the system’s sensitivity. It is well-known that an avalanche photodiode (APD) can be used to improve the signal to noise ratio over a PIN detector, however, APDs operating at the eye-safe wavelengths around 1550 nm are limited in sensitivity by high excess noise. The underlying issue is that the impact ionization coefficient of InAlAs and InP used as the avalanche region in current commercial APDs are very similar at high gain, leading to poor excess noise performance. Recently, we have demonstrated extremely low noise from an Al(Ga)AsSb PIN diode with highly dissimilar impact ionization coefficients due to electron dominated impact ionization. In this paper, we report on the first low noise InGaAs/AlGaAsSb separate absorption, grading and multiplication APDs operating at 1550 nm with extremely low excess noise factor of 1.93 at a gain of 10 and 2.94 at a gain of 20. Furthermore, the APD’s dark current density was measured to be 74.6 μA/cm2 at a gain of 10 which is competitive with commercial devices. We discuss the impact of the excess noise, dark current and responsivity on the APDs sensitivity and, project a noise-equivalent power (NEP) below 80 fW/Hz0.5 from a 230 μm diameter APD and commercial transimpedance amplifier (TIA). The prospects for the next generation of extremely low noise APDs for 1550 nm light detection are discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.