Depth-dependent Detection Mechanisms of Coherent Phonons in n-type GaAs

Ishioka, Kunie; Basak, Amlan Kumar; Petek, Hrvoje

doi:10.1051/epjconf/20134104018

Cited by 1 publication

(1 citation statement)

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“…Several groups have recently turned to time-resolved studies of the LOPC effect, with two main experimental thrusts. Petek and co-workers have demonstrated that the coupled LPP modes, owing to their Raman activity, can manifest as coherent oscillations observed through transient reflectivity measured with visible pulses. − In a second thrust, several groups have measured the transient IR reflectivity from thicker films of SPhP materials, for which the LOPC effect appears as marked modifications to the Reststrahlen band and SPhP resonances. ,,, …”

Section: Resultsmentioning

confidence: 99%

Ultrafast Active Tuning of the Berreman Mode

et al. 2019

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The Berreman effect, by which thin films of polar dielectric materials exhibit strong, narrow resonances near their longitudinal optic (LO) phonon frequency, results in strong material interactions with infrared radiation and offers tremendous potential for infrared nanophotonics. We report the first implementation of the LO-phonon-plasmon-coupling (LOPC) effect to actively tune the Berreman mode of a semiconductor thin film. Using time-resolved ultraviolet pump, infrared probe reflectance spectroscopy, we excite free carriers in a sub-infraredwavelength film of GaN and observe substantial shifts of the Berreman mode as a new, simple version of LOPC-based polariton tuning. We demonstrate resonance shifts (Δω) comparable to the resonance width (δω), realizing a respectable tuning figure of merit Δω/δω ≈ 0.7, and show that the shift can be modulated on a sub-nanosecond time scale. These results provide substantial promise for future ultrafast, wavelength-tunable infrared photonic devices and novel experimental designs for understanding phonon−polariton free-carrier interactions.

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