25 January 2024
Phlux unveils Noiseless InGaAs APDs as first products
Avalanche photodiode (APD) infrared sensor designer and manufacturer Phlux Technology (which was spun out of the UK’s Sheffield University, with a seed funding round of £4m led by Octopus Ventures in December 2022) has announced its first products, the Aura family of 1550nm infrared (IR) devices based on the firm’s Noiseless InGaAs APD technology. The sensors are claimed to be 12x more sensitive than traditional best-in-class indium gallium arsenide (InGaAs) APDs. As a result, the operating range of LiDAR, laser range-finders, and optical fiber test equipment can be extended by up to 50% with Phlux sensors, which are drop-in replacements for existing surface-mount or TO-packaged components.
In new designs, the Aura sensors can enable 12x greater LiDAR image resolution for a given laser power, up to 30% reduction in system size and weight, and up to 40% lower system costs. The size and cost reductions come from using lower-power lasers and smaller optical apertures without impacting system performance. Also, thermal management is simplified because Aura APDs operate at up to +85°C without performance degradation, which is a significantly higher temperature than traditional parts.
Picture: Phlux’s Noiseless InGaAs Aura APD.
“Our Noiseless APD technology is a step-function leap in performance and provides tangible benefits for any company involved with 1550nm lasers,” claims CEO Ben White. “Automotive LiDAR is an exciting application where the move from 905nm to 1550nm lasers is accelerating, not least because the latter is ’eye-safe’. But there are also huge opportunities for our products in telecommunications, laser range-finders, imaging, spectroscopy, gas sensing and optical fiber test equipment, particularly optical time-domain reflectometers,” he adds.
Phlux created its Noiseless InGaAs APD technology by adding an antimony alloy to the compound semiconductor manufacturing process. The resulting sensors can be operated with APD gains of up to 120, enabling even the smallest signals above the noise floor of a connected trans-impedance amplifier (TIA) to be amplified. A further benefit of Aura APDs is their rapid overload recovery, which means that weaker secondary pulses that closely follow a large pulse can be detected.
The Aura APD 200 (200µm optical aperture) and Aura APD 80 (80µm optical aperture) sensors are available as bare die or in industry-standard SMD, chip-on-sub-mount, and TO-46 packages designed to meet MIL-STD 883.
Typical parameters for both devices are responsivity of 0.98A/W at 1550nm, spectral range of 950–1700nm, and excess noise factor of 1.86 at an avalanche gain of 40, or 1.08 at an avalanche gain of 10.
At a gain of 10, the noise equivalent power for the Aura APD 200 diode is 17fW/Hz0.5, its capacitance is 2.4pF and its cut-off frequency is 0.7GHz. The equivalent figures for the Aura APD 80 are 11.1fW/Hz0.5, 0.6pF, and 1.8GHz.
Both devices have a typical operating voltage of –55V to –65V and breakdown voltage of –65V, and their operating temperature range is –40°C to +85°C.
The sensors are in production now and data sheets can be downloaded from the firm’s website.