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Development of THz sources on nanostructured semiconductors and focusing elements on photonic crystals

Project information

Grant agreement ID: INTAS2005-104-7567

  • Start date

    1 April 2006

  • End date

    31 March 2008

Funded under:

IC-INTAS

  • Overall budget:

    € 65 000

  • EU contribution

    € 60 000

Coordinated by:

CHRISTIAN-ALBRECHTS UNIVERSITÄT

Germany

Objective

We propose to study the THz emission properties of electrochemically nanostructured layers and membranes of III-V compounds (InP, GaAs, InAs) under excitation by femtosecond laser pulses for the purpose of developing solid state sources of THz radiation, and to elaborate novel focusing elements for the THz region using properties of photonic crystals (PC). Stimulus for the initiation of the project was recent observation by the authors that (a) nanostructuring of InP leads to about two orders of magnitude increase of the radiated THz power as compared to bulk samples under excitation by 120 fs pulses of 800 nm laser radiation [Phys. Rev. B, Vol. 71, 081306 (2005); Appl. Phys. Lett., Vol. 86, 021904 (2005)], and (b) experimental demonstration of good focusing efficiency in the microwave region for a PC-based concave lens consisting of dielectric rods [Phys. Stat. Sol. A, Vol. 202, R35 (2005)]. Technological conditions for controllable nanostructuring of III-V compounds will be elaborated and optimized, including fabrication of 2D and 3D quasi-ordered porous structures based on self-arrangement phenomena, formation of pores with controllable orientation, transverse sizes and shapes. To provide better conditions for giant spatial fluctuations of the electric field of electromagnetic radiation in the porous network, metal dots (Ag, Pt, Au) will be electrochemically deposited on the internal surface of porous structures. Study of the morphology features by scanning electron and atomic force microscopes as well as of optical transmission and Raman scattering will be carried out. Energy dispersive x-ray analysis will de used to characterize the chemical composition of the fabricated nanostructures. A systematic study of the influence of sample morphology and excitation conditions upon the efficiency of THz emission will be undertaken, the experiments being performed as a function of temperature, polarization, excitation power density, crystallographic orientation and doping level of samples. To discriminate between the nonlinear contribution and architecture-related modification of the transient currents to the resultant THz radiation, experimental terahertz time domain spectroscopy study as well as a theoretical Monte Carlo simulation of hot carrier dynamics and THz emission from photoexcited semiconductors will be performed. The elaboration of novel THz focusing elements relies on computer calculations of the photonic band structure and simulations of the spatial distribution of the electromagnetic fields. The design of the PC-based lenses will be optimized in respect to the material used, PC lattice symmetry, geometrical shapes, in order to reach good focusing properties in wide frequency ranges. Dielectric rods, metallo-dielectrics and semiconducting silicon will be used to fabricate and test PC-based lenses. Possibilities for developing other PC-based THz components such as beam splitters, filters and antennas will be explored.

Coordinator

CHRISTIAN-ALBRECHTS UNIVERSITÄT

Address

Kaiserstrasse, 2
Kiel

Germany

Participants (2)

OXFORD UNIVERSITY

United Kingdom

TECHNICAL UNIVERSITY OF MOLDOVA

Moldova

Project information

Grant agreement ID: INTAS2005-104-7567

  • Start date

    1 April 2006

  • End date

    31 March 2008

Funded under:

IC-INTAS

  • Overall budget:

    € 65 000

  • EU contribution

    € 60 000

Coordinated by:

CHRISTIAN-ALBRECHTS UNIVERSITÄT

Germany