High-speed and high-bandwidth avalanche photodiodes added to family of infrared sensors

Phlux Technology has announced a 30µm optical window version of the Aura family of 1550nm Noiseless InGaAs APDs.

The sensors, which are also available in 80µm and 200µm versions, are 12 times more sensitive than conventional InGaAs APDs and have an inherently fast impulse response and short diffusion tails. The new 30µm version features lower capacitance, ranging from 0.15pF to 0.4pF, which increases the cut-off frequency to 3.5GHz, compared to the 80µm version at 1.8GHz and the 200µm version at 0.7GHz. This makes it excellent for high-speed, time-critical applications, such as those found in gigabit-speed optical communications, including free-space applications and OTDR test equipment.

The 30µm Aura offers an excess noise factor of <3.5 at a gain of 100 with low dark current and sensitivity 12X that of traditional APDs. The spectral noise current at a gain of 50 is 260pA/RtHz, which is 5.2fW/RtHz at R=1.0A/W. Additionally, the damage threshold of 30MW/cm², combined with fast recovery characteristics that minimise attenuation and event dead zones, delivers optimal performance in OTDR and fibre sensing applications. A high optical dynamic range and the ability to operate across a wide range of pulse widths mean that OTDRs can test longer or more lossy fibres.

The high sensitivity of the company's APD sensors extends the range of infrared systems by up to 50% for a given laser power. Alternatively, they can allow for substantial reductions in the laser power required, lowering system costs by up to 40% and reducing size and weight by up to 30%. When laser power is reduced, thermal management is less challenging, and system reliability is enhanced. Aura APDs will operate at temperatures of up to +85C with minimal performance degradation, which is significantly higher than that of traditional sensors. They are designed to meet MIL-STD-883 and are qualified to Telcordia GR-468, making them drop-in replacements for existing surface-mount or TO-packaged components. The sensors will also be offered as bare die later this year.

Phlux CEO Ben White said, "We're seeing growing demand for these high-speed, precision versions of our Aura Noiseless InGaAs APDs, particularly from the optical communications sector but in other areas such as optical test equipment and LiDAR. The expanded product family allows our customers to choose the optimum device characteristics for their application. Whichever product they select, they're guaranteed industry-leading sensitivity and performance."

Noiseless InGaAs APD technology was developed by adding an antimony alloy to the compound semiconductor manufacturing process. The resulting devices operate with an internal gain of up to 120, allowing the detection of even the smallest signals above the noise floor.