CTT offers a wide range of frequency selective devices for the terahertz region of the electromagnetic spectrum - between 30 GHz and 30 THz. Our products can operate at ambient or cryogenic temperatures.
Our technology is remarkably versatile and the examples shown here are intended to give a sense of what we can offer. You are not likely to find exactly what you're looking for displayed here, but don't worry, we've built thousands of devices of wide ranging characteristics. We're confident we have a solution to suit your needs.
Here we show the measured performance of single devices. For sophisticated applications a combination of items may well be needed. The design and implementation of such schemes is our strength and our heritage.
Contact us to discuss your needs.
Low-pass edge filters
In a typical low-pass device (lower frequencies are transmitted) average in-band transmission efficiency is ~90% while attenuation at frequencies above the transition will be typically -25dB (0.3 %).
We have made such devices with edge frequencies between 25 GHz and 31.5 THz (the latter being the highest achievable with this technology). So we cover more than three orders of magnitude in frequency.
High-pass edge filters
In a high-pass device (higher frequencies are transmitted) the transmission window is limited to a range of about one octave above the edge frequency.
Here we present the measured transmission spectra of three variations on our recipe for a 3 THz high-pass device. Note the fine tunability of the edge that can be deliberately achieved. These devices are designed to transmit radiation between 3 and 6 THz.
Out of band attenuation at frequencies below the transition is better than -40dB.
We have made high-pass devices with edge frequencies between 50 GHz and 12 THz (covering more than two orders of magnitude in frequency).
Band-pass filters
The peak transmission efficiency of a band-pass structure will vary with frequency and bandwidth requirement. Here is an example centred at 3.4 THz (about 90 microns in wavelength).
Let us know what you need in terms of:
(i) centre frequency
(ii) bandwidth (the frequencies at which transmission drops to half-maximum)
(iii) attenuation
(iv) the range of frequencies over which attenuation is to be achieved
We have made band-pass devices between 70 GHz and 12 THz (more than two orders of magnitude in frequency).
Notch Filters
Below we present the measured transmission performance of a 183 GHz notch filter. It is designed to cut out a spectral line associated with water, operating essentially as an inverse band-pass filter. We present its transmission on both linear and logarithmic scales in order to spotlight the in-band attenuation and the efficiency of transmission either side of the stop band.
The attenuation is -25dB at the desired frequency, but frequencies either side of the stop band are efficiently transmitted.
Dichroics
Dichroic beam-splitters are available in both low-pass and high-pass configuration.
On the right we present an example which is high-pass in transmission with an edge at 140 GHz. The device is designed to separate frequency bands centred at 70 GHz (reflected) and 200 GHz (transmitted). The device operates at 22.5 degrees to the broadband incoming radiation.
Devices can be manufactured at up to 700 mm in diameter.
We recommend that you contact us to discuss your application in advance.
Photolithographic Polarisers
Our polarisers use a single ultra-thin polymer substrate on which a fine pattern of metal strips is deposited. The result is a low-loss device with excellent polarisation performance over a broad range of frequencies.
Pattern repeat distances vary from 1 to 20 microns offering excellent performance at frequencies as high as 30 THz. Devices are available at diameters up to 800 mm.
Other Products
Our versatile technology can create solutions to your terahertz application. For example we offer:
Anti-reflection coatings
Waveplates
Flat lenses
If we can't solve your problem, we may well know someone who can. Get in touch by clicking on the button below.
