Product/Service

Avalanche Photodiode (APD) LLAM Series

Source: Excelitas Technologies

Excelitas Technologies’ LLAM series of Silicon and InGaAs avalanche photodiodes (APD) receiver modules feature an APD, thermoelectric cooler (TEC) and a hybrid, all in the same hermetically-sealed modified 12-lead TO-66 flange package for increased heat sinking. The use of a TEC ensures lower noise and constant responsivity over a 5⁰C to 40⁰C ambient temperature range.

The LLAM series modules are specifically designed for the detection of high-speed, low-light analog signals. The Si APDs used in these devices are the same as used in Excelitas’ C30902EH and C30954EH products, while the InGaAs APDs are used in the C30645EH and C30662EH products. These detectors provide very good response between 830 and 1550 nm and very fast rise- and fall-times at all wavelengths. The preamplifier section of the module uses a very low noise GaAs FET front end designed to operate at higher transimpedance than Excelitas’ regular C30950 Series.

An emitter follower is used as an output buffer stage. To obtain the wideband characteristics, the output of these devices should be capacitively- or AC-coupled to a 50 Ω termination. The module must not be DC-coupled to loads of less than 2,000 Ohms. For field use, it is recommended that a temperature-compensated HV supply be employed to maintain a constant responsivity over temperature.

Excelitas’ InGaAs LLAM-1550E Preamplifier Modules, with 1550 nm peak response, are designed to exhibit higher damage thresholds, thus providing greater resilience when exposed to high optical power densities.

The LLAM series modules are offered as standard, RoHS-compliant, commercial off-the-shelf (COTS) products. Excelitas offers customized modules tailored for your specific needs; modifications include bandwidth and gain optimization, use of different APDs, FC-connectorized packaging.

Key Features

  • System bandwidth of 50 MHz and 200MHz
  • Ultra low noise equivalent power (NEP)
  • Spectral response range:
    • Si APD: 400 to 1100 nm
    • InGaAs APD: 1100 to 1700 nm
  • Typical power consumption: 150 mW (without TEC powered on)
  • ±5 V amplifier operating voltages
  • 50 Ω AC load capability (AC-Coupled)
  • Hermetically-sealed TO-66 flange package for additional heat sinking
  • High reliability
  • Light entry angle, over 130°
  • Model 1550E exhibits enhanced damage threshold
  • RoHS-compliant
  • Available in both COTS and custom variations

Applications

  • LIDAR
  • Range finding
  • Confocal microscopy
  • High-speed, extreme low-light detection
  • Distributed temperature sensing (DTS)
  • Analytical instrumentation
  • High-speed, free-space optical communication