A novel multiplexed THz spatial modulator for fast sub-wavelength imaging and spectroscopy

Szelc, Jedrzej, Rutt, H.N. and Moktadir, Z. (2009) A novel multiplexed THz spatial modulator for fast sub-wavelength imaging and spectroscopy. 2nd Annual Meeting on THz Measurement Techniques, London, UK. 28 Jun 2009.

Abstract

We report on the current state of the development of a sub-wavelength THz spatial modulator array - a multi-pixel THz imaging device. The modulator allows fast image acquisition with greatly improved spatial resolution. Additionally, it is expected that the modulator can be used for multiplexed Fourier Transform Spectroscopy enabling micro-spectroscopy characterization of samples within the THz regime.

The device consists of an array of sixteen THz transmission windows (pixels) of sub-wavelength diameter. The transmission of each of the sub-wavelength pixels can be varied electronically allowing amplitude modulation of the THz signal. The complete array of sixteen pixels is frequency multiplexed. The modulator can deliver a 4x4 pixel image within a single integration time of a photodetector. The array is mechanically scanned over the sample, yielding a factor of 16 improvement in the speed of image acquisition in comparison to a single hole, sub-wavelength scanning imaging technique.

Several variants of the device with varying pixel diameters were already fabricated and are currently tested and characterized. As such, we will present and discuss some of the experimental results. These include the characterization of the device within MWIR and LWIR bands as well as some calculations of the device's expected performance within the THz band.

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