The simplest way to use a detector is with a receiver circuit. Here the quality is judged by the amount of noise produced. Our extremely low-noise silicon and InGaAs APDs (SARP-Series and IAG-Series) offer the optimal pre-requisites for detectors. For the entire system, however, the amplifier noise is the dominant source of noise.
To reduce the overall noise of the detector/amplifier module, the capacitance connected to the amplifier has to be as small as possible. This is achieved by making the connections as short as possible to minimise the parasitic capacitance together with the exceptionally low junction capacitance of our APDs.
H0 series: In our H0 series of APD receivers, the goal was to achieve low noise performance with high responsivity without the need for a TE cooler; only a thermistor would be required for stability. The inherent noise of the receivers should be zero. Although this is physically not possible, our developers came very close to meeting this goal. Depending on the integrated feedback resistor, a bandwidth from DC up to 80 MHz can be achieved. If the SAR500, our Si APD with a diameter of 500 µm, is integrated, the module has a noise equivalent power (NEP) of only 4.86 fW/√Hz at an amplification of 3 x 106 V/W without the need for an expensive and power hungry TE cooler. With the 80 µm or 20 0µm InGaAs APD of the IAG series, the following value can be achieved: 1.1 x 106 V/W @ 0.47 pW/√Hz.
Due to the very compact, modified TO-5 housing measuring ~ø5mm, the H0 series APD receivers can be integrated into small systems with which, for example, distances can be measured or the smallest light signals detected.
