We are pleased to offer these APD photoreceivers for ultralow-light-level detection. The Model1647 Avalanche Photodiode Photoreceiver consists of a high-gain avalanche photodiode, followed by a low-noise amplifier and internal bias supply all in a compact module—no need for separate high-voltage input. We optimize the noise performance of these APDs while enhancing the overall sensitivity of the APD photoreceiver with the inclusion of a linear amplifier. The amplifier is AC-coupled to allow measurements of nW of modulation on large CW signals. The result is an APD and amplifier combination with a low noise-equivalent-power as low as 1.6 pW/√Hz (typical) with high conversion gain. The APD gain is adjustable so that you can optimize your signal-to-noise ratio for your particular optical power.

For your convenience, these APD photoreceivers have a built-in temperature-compensation bias circuit so you don’t need to worry about small temperature changes compromising your measurements. And, the DC current in the APD is limited so as to reduce damage to the amplifier and APD due to excessive currents.

These APD photoreceivers include both single-ended and differential outputs. When only one SMA output is used (single-ended), the photoreceiver operates like any of our other standard high-speed photoreceivers. When both SMA outputs are used (differential), each output is the opposite polarity of the other and can be used as a pair, e.g. on transmission line setups to minimize noise.

These APD photoreceivers come in an RF-shielded package with their own power and monitor cables. You’ll only need a ±15-V power supply such as our Model 0901 .

1647Frequency responsivity of the photodiode in the Model 1647 .1647Typical step and impulse response of the Model 1647.1647Typical responsivity of the Model 1647 .