Ultrafast Modulators for 100GHz and 140GHz wave sources

Many of our scientific customers are well aware of the whole Terasense product line, including our ultrafast modulators we usually offer together with our fixed-frequency terahertz wave sources. However, despite the fact we’ve been successfully selling these modulators -also known as switches- for a number of years, and have an elaborate datasheet/promotion brochure for them, they haven’t been added as a stand-alone product and there is no dedicated product web-page at our web-site.  Well, it’s time to fix it and this article will surelybe instrumental in putting our ultrafast modulators into the spotlight. Below you will find some of the most essential information complemented with key specs of ultrafast modulators.

The ultrafast waveguide modulator on PIN diode is designed for fast switching of the input microwave signal off. The device is reciprocal (S21 = S12). The modulator consists of a waveguide section (Mod) and a sub-modulator (SubMod). A silicon PIN diode with a thin base (i-layer) is used as an active element in the waveguide section.

The p-type and n-type regions of the PIN diode are typically heavily doped because they are used for ohmic contacts. The wide intrinsic region (i-layer) makes the PIN diode an inferior rectifier (one typical function of a diode), but it makes it suitable for attenuators, fast switches, photodetectors, and high voltage power electronics applications. The scheme of switching the diode into a waveguide line is resonant. The sub-modulator is made based on the wiring scheme that ensures fast relaxation of the space charge in the base of the PIN diode. 

SPECIFICATIONS

Base frequency, GHz 85 – 100, 140

Bandwidth, GHz ±1

Insertion loss, dB ≤ 1.5

Attenuation, dB ≥ 25

Switching time, ns < 2

Maximum input microwave power, W 0.6

It’s critical to keep in mind that our ultrafast modulators are fully compatible with our 100 GHz and 140 GHz generators (IMPATT diodes) which  TERASENSE offers. So, there is an opportunity of up-selling and cross-sales. Moreover, our modulators can be used as RF switches and attenuators. Most importantly, these modulators can be sold as external or built-in devices, depending on the customer preferences or specifics of the THz setup in question. At times Terasense engineers can do real miracles of customization. The pic below shows our ultrafast waveguide (external) connected to our 100GHz wave source.

We have to admit that this product can potentially kindle the interest of only R&D or scientific clients, while other Terasense products like THz imaging cameras/sensor arrays can be interesting for both research and industrial sectors.

If you have any questions, you are welcome to contact Terasense.