DocumentCode :
2534575
Title :
Resonant crossover of terahertz loss to gain in a Bloch oscillating InAs/AlSb super-superlattice
Author :
Savvidis, Pavlos G. ; Kolasa, Borys ; Allen, S. James ; Lee, Greg
Author_Institution :
Center for Terahertz Sci. & Technol., California Univ., Santa Barbara, CA, USA
fYear :
2004
fDate :
16-19 Aug. 2004
Firstpage :
405
Abstract :
Summary form only given. Terahertz absorption in waveguides loaded with InAs/AlSb super-superlattice mesas reveals a frequency dependent cross over from loss to gain that is related to the Stark ladder produced by an applied DC electric field. Resonant crossover is indicated by an increase in terahertz transmission as the Stark splitting or Bloch frequency determined by the applied DC electric field exceeds the measurement frequency. The measurements are carried out at room temperature. Super-superlattice mesas are loaded into a terahertz waveguide, 10 μm high and ∼300 μm wide, defined by photonic band gap side walls and metallic ceiling and floor. Terahertz radiation (1.5-2.6 THz) from the UCSB free-electron lasers is focused on the entrance and guided to a detector. Electric field domains appear to be suppressed in the super-superlattice comprised of many very short segments of superlattice, interrupted by heavily doped InAs regions. Scaling of the crossover voltage by the terahertz frequency indicates that ∼75% of the super-superlattice participates in the Stark ladder. These results indicate that super-superlattices in terahertz waveguides as described here can provide a terahertz gain medium without population inversion and a resonator for a terahertz Bloch oscillator.
Keywords :
III-V semiconductors; Stark effect; aluminium compounds; electromagnetic wave absorption; electromagnetic wave transmission; heavily doped semiconductors; indium compounds; semiconductor superlattices; submillimetre wave oscillators; waveguides; 1.5 to 2.6 THz; 10 micron; 293 to 298 K; 300 micron; Bloch frequency; Bloch oscillating InAs-AlSb super-superlattice; InAs-AlSb; Stark ladder; Stark splitting; applied DC electric field; crossover voltage scaling; electric field domains; free-electron lasers; frequency dependent crossover; heavily doped InAs regions; metallic ceiling; photonic band gap sidewalls; resonant crossover; room temperature; terahertz Bloch oscillator; terahertz absorption; terahertz gain; terahertz loss; terahertz radiation; terahertz transmission; terahertz waveguide; Absorption; Electric variables measurement; Frequency dependence; Frequency measurement; Loaded waveguides; Photonic band gap; Resonance; Submillimeter wave measurements; Temperature; Waveguide discontinuities;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Nanotechnology, 2004. 4th IEEE Conference on
Print_ISBN :
0-7803-8536-5
Type :
conf
DOI :
10.1109/NANO.2004.1392365
Filename :
1392365
Link To Document :
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