Precise, low-noise terahertz measurements at room temperature? Gentec-EO’s T-RAD makes it possible!

22 Sep 2023

Terahertz sources are tricky to measure mostly because they require high sensitivity and flat spectral response from the detector. Previous technologies available on the market had to resort to cooling their devices to minimize the noise.  

As a pioneer of laser beam measurements, Gentec-EO remains ahead of the crowd with a complete line of room-temperature-operated THz detectors and T-RAD lock-in radiometers. This lineup of radiometers enable extremely low-noise, broadband terahertz measurements. They are compact, work at room temperature, and do not require any exterior source of cooling. They are also spectrally flat over the entire terahertz range, from 30 THz to 0.1 THz.

Versatility

To adapt to every situation, users can choose from different detectors that best fits their needs. The instrument comes in two parts; the first is the electronic module, and the second is the detector head.

The electronic module is called a T-RAD (or T-RAD-ANALOG depending on the desired read-out). The T-RAD model is a microprocessor-based lock-in amplifier that connects to a PC via USB. The T-RAD-ANALOG version is meant to be used directly with an oscilloscope or a lock-in amplifier with a BNC connector. Both solutions have their advantages.

T-RAD advantages:

• Connects to a PC via USB for a digital read-out
• Comes with free software, making it not only a more user-friendly experience but also enabling live data analysis in graphic and digital formats
• Addresses thermal drift
• Does not require extra electronics such as an oscilloscope or lock-in amplifier

T-RAD-ANALOG advantages:

• Higher sensitivity
• Even lower noise, down to 1 nW/Hz^1/2
• Less expensive (if you already have an oscilloscope or lock-in amplifier)

Choosing the appropriate detector

Both T-RAD versions can be paired with two different detector heads each. These heads can either be chosen with a 5-mm or 9-mm aperture. All heads come with a broadband absorber to give a smooth response across the whole operating spectral range while offering an impressively wide dynamic range, starting at a few nW and measuring up to 20 mW.

At these noise levels, they are a remarkably inexpensive solution compared to what’s out there, and don’t require cooling

Custom solutions

If you can’t find what you’re looking for in our off-the-shelf solutions, we will gladly work with you on a customized measurement system. Gentec-EO has a dedicated custom projects department to adapt to your exact needs, and is flexible enough to support any size order.

Calibrating in the THz region – a challenge

The calibrated range using typical traceable detector calibration methods is somewhat limited and doesn’t begin to cover the broad Terahertz wavelength range. Gentec-EO is proud to be working directly with NIST researchers and other well-known international laboratories to expand the calibration capabilities of both parties in the terahertz domain.

We have discovered a spectrally flat and very high absorption material for the THz range, from 10 µm to 440 µm (and up to 600 µm) that is now used as the THz absorber for one of our terahertz detector heads. This probe, model THZ12D-3S-VP, is believed to be the first low-uncertainty spectral reference in this portion of broad THz spectral range.

To learn more about terahertz measurements and the Gentec-EO T-RAD series, come see us at IRMMW-THz in Montréal from September 17^th to 22^nd. You’ll have the chance to chat directly with Don Dooley, our expert in terahertz measurement, and T-RAD designer. If you are not available to come meet us at the conference, you can also contact your local laser beam measurement expert.