Abstract-Quantum-Enhanced Second-Order Nonlinearity in Graphene: The Role of Wave Momentum and DC Biasing

Raeis-Zadeh, S.M. ;  Strickland, D. ; Safavi-Naeini, S.

 Department of Electrical and Computer EngineeringCenter of Intelligent Antenna and Radio Systems (CIARS), University of Waterloo, Waterloo, ON, Canada

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=7360105

A comprehensive and rigorous analysis is presented for the study of terahertz photomixing process in a biased graphene layer, when two obliquely incident waves are used as primary excitation. The second-order nonlinearity tensor of graphene associated with the difference frequency generation (DFG) is calculated to evaluate the amount of induced terahertz current density. In this analysis, we are calculating the significant contribution of the photon drag effect to the DFG and consequently to the terahertz wave generation. We also examine the effect of DC current biasing on the DFG as the Fermi energy level of graphene changes. Our results show that the DFG in graphene can be enhanced by at least two orders of magnitude when the Fermi energy level of graphene becomes equal to the energy of incident photon. This paper provides more insight into the contributing factors in the DFG process and allows the realization of more optimal graphene-based photomixing devices.

Abstract-Numerical simulation of high impedance T-match antennas for terahertz photomixers

Lars Juul; Martin Mikulics; Michel Marso; Mauro F. Pereira

http://spie.org/Publications/Proceedings/Paper/10.1117/12.2188020

This paper summarizes an efficient numerical method to design terahertz photomixers. The method is illustrated by comparisons with designs in the literature. Next we deliver complementary results to the study of two recently introduced photomixer designs based on the high impedance T-match antenna. The estimated output power of the improved design is 9.0μW, which is an improvement of three times over reference photomixers .

Paper-A terahertz photomixer based on plasmonic nanoantennas coupled to a graphene emitter

Pai-Yen Chen¹ and Andrea Alù
http://iopscience.iop.org/0957-4484/24/45/455202;jsessionid=662617F0AD91E1046CDC2A989905027D.c2

pychen@utexas.edu alu@mail.utexas.edu
Department of Electrical and Computer Engineering, The University of Texas at Austin, 1 University Station C0803, Austin, TX 78712, USA

We propose the concept of a graphene-based nanoantenna-enhanced photomixer to realize wideband-tunable terahertz (THz) frequency generation. When two laser beams are focused on the graphene nanoemitter of a planar field-emission diode, THz current oscillations can be created at the emitter tip through the optical heterodyne. Graphene's optical transparency allows suitably designed plasmonic nanoantennas to boost the mixing of laser radiation at the emitter tip, significantly increasing the overall produced photomixing current. The THz wave generated at the graphene emitter is then coupled to a loading circuit, thanks to the THz wave confinement in the graphene nanostructures. Our design is ideally suited for THz sources that may be tuned from DC to 10 THz by simply shifting the frequency offset of two pumping lasers.