Photonics at Terahertz Frequencies

The terahertz (THz) frequency range has been termed the “THz gap” for a long time until efficient sources of THz radiation finally became available. Nevertheless, the nonlinear optical properties of materials at the THz frequencies remain largely unexplored due to many challenges of such experimental studies. Within this research direction, we study, both theoretically and experimentally, nonlinear optical properties of various materials at the THz frequencies.

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Our research group, working together with our uOttawa and international collaborators, made several significant contributions towards filling this knowledge gap. Specifically, we have demonstrated, by means of a simple analytical model based on anharmonic oscillator, that the nonlinear refractive index of some crystals is several orders of magnitude larger compared to its values in the visible spectral range. This result is of high fundamental and practical significance because it is a step towards the development of nonlinear optical devices for THz frequencies with applications in nonlinear spectroscopy, which holds promise in non-intrusive medical diagnostics.

Our on-going effort is the measurement of the nonlinear coefficients of various solids and water vapour at THz frequencies. Moreover, we explore how microstructuring can be used to enhance optical responses of materials at THz frequencies.