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Ultrafast opto-terahertz photonic crystal modulator
1Institute of Physics, Academy of Sciences of the Czech Republic, Prague.
Optics Letters
|February 20, 2007
Summary
We developed an agile optical switch for terahertz (THz) radiation using a photonic crystal. This device efficiently modulates THz beams with ultrashort laser pulses, showing a fast response time.
Area of Science:
- Optoelectronics
- Photonics
- Terahertz Science
Background:
- Terahertz (THz) radiation applications require efficient control methods.
- Photonic crystals offer unique properties for manipulating electromagnetic waves.
- Semiconductor materials can be optically modulated for device applications.
Purpose of the Study:
- To present an agile, optically controlled switch/modulator for terahertz radiation.
- To investigate the modulation efficiency of a photonic crystal with a defect layer.
- To determine the response time of the optically controlled THz modulator.
Main Methods:
- Fabrication of a one-dimensional photonic crystal with a gallium arsenide (GaAs) defect layer.
- Enhanced THz electric field localization within the photonic structure.
- Optical control using ultrashort 810 nm laser pulses to excite photocarriers in GaAs.
Main Results:
- Efficient modulation of the THz beam achieved via optical excitation.
- Effective modulation observed at low photocarrier concentrations (approx. 10^16 cm^-3).
- The switch demonstrated a response time of approximately 130 picoseconds (ps).
Conclusions:
- The proposed device serves as an effective and agile optically controlled THz switch/modulator.
- The design leverages enhanced THz fields in photonic crystals for efficient modulation.
- The fast response time makes it suitable for pulsed THz applications.
