[PDF]    http://dx.doi.org/10.3952/lithjphys.49304

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 49, 299–303 (2009)

A. Urbanowicza, A. Geižutisa,b, and A. Krotkusa
aSemiconductor Physics Institute, A. Goštauto 11, LT-01108 Vilnius, Lithuania
E-mail: aurban@pfi.lt
bDepartment of Electronic Systems, Vilnius Gediminas Technical University, Naugarduko 41, LT-03227 Vilnius, Lithuania

Received 29 January 2009; revised 3 August 2009; accepted 15 September 2009

Various cw terahertz (THz) photomixers were investigated and compared. Beams of two cw, tunable, single mode DFB (distributed feedback) diode lasers were used for illumination of the devices. Simple photoexcited gap structure, spiral-type and dipole-type integrated antennae patterns photomixers were used while carrying out investigations. Cw THz radiation has been generated by photoconductive devices made using low-temperature-grown GaAs layers. Antennae fabricated on GaAs and GaBiAs layers were used for coherent detection of cw THz radiation. It was obtained that the sensitivity of GaBiAs detectors is more than two times higher than in the case of GaAs detectors. GaAs emitters with integrated spiral-type antennae were most efficiently emitting in the low frequency range; enhanced bias voltages of such devices result in generated THz power comparable with the photomixers with interdigitated contact structures.
Keywords: optical mixing, terahertz radiation, GaAs, GaBiAs
PACS: 42.65.Re, 72.30.+q, 78.47.+p

A. Urbanowicza, A. Geižutisa,b, A. Krotkusa
aPuslaidininkių fizikos institutas, Vilnius, Lietuva
bVilniaus Gedimino technikos universitetas, Vilnius, Lietuva

Ištirti ir palyginti skirtingi netrūkios terahercinės (THz) spinduliuotės fotomaišikliai, kurių žadinimui buvo naudojami du derinamo bangos ilgio vienamodžiai lazeriniai diodai. Atliekant tyrimus buvo naudojami dipolinių ir spiralinių antenų fotomaišikliai. Netrūkios THz spinduliuotės generavimui naudotos dipolinės arba spiralinės antenos, suformuotos ant žemoje temperatūroje (ŽT) auginto GaAs sluoksnio paviršiaus. THz spinduliuotė koherentiškai detektuota dipolinėmis antenomis, suformuotomis ant ŽT GaAs ir ŽT GaBiAs epitaksinių sluoksnių. Paaiškėjo, kad GaBiAs detektorių jautris du kartus didesnis nei GaAs detektorių. GaAs emiteriai su spiralinėmis antenomis efektyviausiai generuoja žemų dažnių srityje; didinant maitinimo įtampą šių maišiklių optinės galios vertimo į THz spinduliuotę efektyvumas siekia 2\cdot10–5.

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