Thorlabs' PDA10JT-EC Amplified Detector is a thermoelectrically cooled photoconductive HgCdTe (mercury cadmium telluride, MCT) detector. It is sensitive to light in the mid-IR spectral range from 2.0 to 5.4 µm. Two rotary switches control the gain amplifier and detector package bandwidth, allowing performance to be optimized for a variety of applications. The gain switch features eight discrete steps from 0 - 40 dB, while the bandwidth switch provides eight discrete steps from 1.25 - 160 kHz. The thermoelectric cooler (TEC) uses a thermistor feedback loop to hold the temperature of the detector element at -30 °C, minimizing thermal contributions to the output signal.

For best results, we recommend connecting the output cable (not included) to a 50 Ω termination. Because the detector is AC coupled, it requires a pulsed or chopped input signal. AC-coupled detectors will not see unchopped CW light because they are only sensitive to intensity changes, not absolute intensity.

The detector package incorporates many of the same mechanical features as our other mounted photodetectors. An internal SM1 (1.035"-40) threading allows Ø1" lens tubes to be mounted in front of the detector element. Two M4 tapped holes connect a Ø1/2" post to the housing in one of two perpendicular orientations, as shown in the image at the top of the page. The PDA10JT-EC includes a 100 - 240 VAC power adapter. If you require a different adapter plug, please contact Tech Support prior to ordering. An SM1RR Retaining Ring is also included.

This detector's output signal depends nonlinearly on the optical input power; for a plot of this, see the Graphs tab. Please note that inhomogeneities at the edges of the active area of the detector can generate unwanted capacitance and resistance effects that distort the time-domain response of the output. Thorlabs therefore recommends that the incident light is well centered on the active area. The SM1 (1.035"-40) threading on the housing can be connected to an SM1 lens tube; the lens tube can be used to mount an iris or pinhole in front of the detector element. Because the detector package protrudes 3.9 mm beyond the front of the threading, optics and optomechanics cannot be attached directly to the housing.

In addition to the HgCdTe detector sold here, Thorlabs manufactures a InAsSb detector with broader wavelength sensitivity and higher bandwidth at the expense of a higher NEP. If a more compact detector housing is desired, we also offer room-temperature amplified photodetectors.

One may consider interesting but largely abandoned research on Microwave Biased Photoconductors e.g.

"The photoconductive detector with microwave bias gives a high performance front end for optical receivers. Its advantage over other detectors is a high S/N at low light levels for information bandwidths approaching a gigahertz. The full potential is reached when the volume of the phototransducer can be very small, which means with intrinsic photoconductors and a diffraction-limited optical system. By definition, photoconductivity is the increase of conductivity of a material because of the absorption of electromagnetic radiation. In an appropriate circuit, this change in conductivity controls the delivery of signal power to an output circuit. In contrast, capacitive contacts can be used with a high-frequency bias supply. In principle, it can also perform well with extrinsic photoconductors in spite of the increased size needed to give reasonable optical absorption, but this application has not been studied in detail."

Article Chapter 11 Microwave-Biased Photoconduetive Detector

The photoconductive detector with microwave bias gives a high performance front end for optical receivers. Its advantage over other detectors is a high S/N at low light levels for information bandwidths approaching a gigahertz. The full potential is reached when the volume of the phototransducer can be very small, which means with intrinsic photoconductors and a diffraction-limited optical system. By definition, photoconductivity is the increase of conductivity of a material because of the absorption of electromagnetic radiation. In an appropriate circuit, this change in conductivity controls the delivery of signal power to an output circuit. In contrast, capacitive contacts can be used with a high-frequency bias supply. In principle, it can also perform well with extrinsic photoconductors in spite of the increased size needed to give reasonable optical absorption