A Global Approach for Modeling and Analysis of Edge-Coupled Traveling-Wave Terahertz Photoconductive Sources

Neshat, Mohammad; Saeedkia, Daryoosh; Rezaee, Leila; Safavi-Naeini, S.

doi:10.1109/tmtt.2010.2050379

Cited by 20 publications

(19 citation statements)

References 39 publications

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“…Acceleration of these photogenerated carriers by the built-in field is also modulated by the same frequency− i.e., E (x, y, t) = E (x, y) e jωt triggers radiation of the desired CW THz wave, in the absence of an external applied bias. Using the same procedure as reported in [19,20], in order to model the optical generation, we initially obtain the intensity distribution from the time-averaged Poynting vector. In simulating the optical characteristics of the individual Emitter structure, we used absorbing boundary conditions at all sides of the simulation domain.…”

Section: Cw Operation Of Thz Photomixer Emittersmentioning

confidence: 99%

Unbiased continuous wave terahertz photomixer emitters with dis-similar Schottky barriers

Mohammad-Zamani¹,

Moravvej-Farshi²,

Neshat³

2015

Opt. Express

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We are introducing a new bias free CW terahertz photomixer emitter array. Each emitter consists of an asymmetric metal-semiconductor-metal (MSM) that is made of two side by side dis-similar Schottky contacts, on a thin layer of low temperature grown (LTG) GaAs, with barrier heights of difference (ΔΦ(B)) and a finite lateral spacing (s). Simulations show that when an appropriately designed structure is irradiated by two coherent optical beams of different center wavelengths, whose frequency difference (∆f) falls in a desired THz band, the built-in field between the two dis-similar potential barriers can accelerate the photogenerated carriers that are modulated by ∆ω, making each pitch in the array to act as a CW THz emitter, effectively. We also show the permissible values of s and ΔΦ(B) pairs, for which the strengths of the built-in electric field maxima fall below that of the critical of 50 V/μm- i.e., the breakdown limit for the LTG-GaAs layer. Moreover, we calculate the THz radiation power per emitter in an array. Among many potential applications for these bias free THz emitters their use in endoscopic imaging without a need for hazardous external biasing circuitry that reduces the patient health risk, could be the most important one. A hybrid numerical simulation method is used to design an optimum emitter pitch, radiating at 0.5 THz.

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Section: Cw Operation Of Thz Photomixer Emittersmentioning

confidence: 99%

Unbiased continuous wave terahertz photomixer emitters with dis-similar Schottky barriers

Mohammad-Zamani¹,

Moravvej-Farshi²,

Neshat³

2015

Opt. Express

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“…The drift-diffusion model can explain physical phenomena such as optical generation of carriers and currents, and the field-screening effect. In addition, this model is sufficiently simple and therefore needs far less computational time as compared to other models [17].…”

Section: B Carrier Transport Modelmentioning

confidence: 99%

“…Substituting the current equations into the continuity equations from a set of the drift-diffusion equations, one can obtain three partial differential equations with the dependent variables of , and as follows [17]:…”

Section: B Carrier Transport Modelmentioning

confidence: 99%

Hybrid Computational Simulation and Study of Continuous Wave Terahertz Photomixers

Khabiri

Neshat

Safavi-Naeini

2012

IEEE Trans. THz Sci. Technol.

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A hybrid numerical simulation method is presented to model and analyze integrated terahertz (THz) photomixer antennas. The proposed computational method combines an optoelectronic solver and a full-wave electromagnetic solver to rigorously model continuous wave (CW) THz photomixer sources. In this hybrid computational approach, the photomixer source is modeled in a rigorous manner without any approximation. The optoelectronic solver is used to find absorbed optical intensity and optical carrier generation rate inside the fast photoconductive region through solving an optical scattering problem. Then, the equations governing the charge carrier transport inside the photoconductor are solved to give THz photo-current by considering realistic material parameters. Finally, through a full-wave electromagnetic solver, and using calculated photo-current from the optoelectronic simulator, antenna parameters and radiated THz power are obtained. Using the proposed hybrid simulation method the effects of photomixer parameters on the THz photo-current and radiated power is rigorously investigated for several geometries. Moreover, results of a parametric study on various factors such as carrier lifetime of material, incident optical power density, applied bias voltage, THz beat frequency, and the gap size are presented. The method can be used for accurate design refinement at pre-fabrication stage.

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“…For the net recombination rate in the drift-diffusion model, the Shockley-Read-Hall (SRH) and Auger processes are considered [17].…”

Section: B Modeling Of Optical Carrier Generation and Carriermentioning

confidence: 99%

“…In this regard, along the outer (non-contact) edges of devices, homogeneous (reflecting) Neumann boundary conditions are imposed so that current only flows out of the device through the contacts. In the absence of surface charge along such edges, the normal electric field component becomes zero [17]. At the interface of the metal and semiconductor, the boundary condition for the Schottky contact is based largely on the approach introduced by Crowell and Sze [18].…”

Section: B Modeling Of Optical Carrier Generation and Carriermentioning

confidence: 99%

Modeling and designing an unbiased CW terahertz photomixer emitters

Mohammad-Zamani

Moravvej-Farshi

Neshat

2014

2014 Third Conference on Millimeter-Wave and Terahertz Technologies (MMWATT)

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A Global Approach for Modeling and Analysis of Edge-Coupled Traveling-Wave Terahertz Photoconductive Sources

Cited by 20 publications

References 39 publications

Unbiased continuous wave terahertz photomixer emitters with dis-similar Schottky barriers

Unbiased continuous wave terahertz photomixer emitters with dis-similar Schottky barriers

Hybrid Computational Simulation and Study of Continuous Wave Terahertz Photomixers

Modeling and designing an unbiased CW terahertz photomixer emitters

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