High-performing nonlinear visualization of terahertz radiation on a silicon charge-coupled device.

Mostafa Shalaby,Christoph P Hauri,Carlo Vicario

doi:10.1038/ncomms9439

Mostafa Shalaby, Christoph P Hauri + Show 1 more

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https://doi.org/10.1038/ncomms9439

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Abstract

Photoinduced electron transitions can lead to significant changes of the macroscopic electronic properties in semiconductors. This principle is responsible for the detection of light with charge-coupled devices. Their spectral sensitivity is limited by the semiconductor bandgap which has restricted their visualization capabilities to the optical, ultraviolet, and X-ray regimes. The absence of an imaging device in the low frequency terahertz range has severely hampered the advance of terahertz imaging applications in the past. Here we introduce a high-performing imaging concept to the terahertz range. On the basis of a silicon charge-coupled device we visualize 5–13 THz radiation with photon energy under 2% of the sensor's band-gap energy. The unprecedented small pitch and large number of pixels allow the visualization of complex terahertz radiation patterns in real time and with high spatial detail. This advance will have a great impact on a wide range of terahertz imaging disciplines.

Highlights

Photoinduced electron transitions can lead to significant changes of the macroscopic electronic properties in semiconductors
Our work introduces the well-established Charge-coupled devices (CCDs) concept to the THz regime, allowing for THz recording on a large size 1,360 Â 1,024 standard silicon chip with a very small pixel size of 4.65 mm
Some reports extended the use of the CCD sensors into the mid-infrared range, exploiting multi-photon absorption of intense radiation[22,23]

Summary

Introduction

Photoinduced electron transitions can lead to significant changes of the macroscopic electronic properties in semiconductors. The response time is slow, the read-out time is long and the thermal sensor is highly sensitive to fluctuation of the ambient temperature, as the associated thermal energy is in the range of the THz photon energy to be detected (E25 meV at 290 K, E6 THz) This gives rise to a detector background radiation which can vary during exposure time. The unprecedented small pitch and large number of pixels allow visualizing complex terahertz radiation patterns in real time and with high spatial detail While such technology was available in the mid-infrared range (3–15 mm) a corresponding imaging technique in the THz range (15–1,000 mm) has so far been lacking. This process is effective only when certain radiation intensity is reached, it is followed by a dramatic increase in free carrier generation efficiency, which leads to a very high measured sensitivity

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