Terahertz Signal Generation in 1-D Photonic Crystals

Theoretical and numerical results are presented to assure that a tunable, narrow-band, coherent THz radiation source can be based on parametric down-conversion in aphotonic crystal. Our proposal is based on down-conversion mixing and a local-field enhancement mechanism that is available by tuning each of the two driving laserfields either to band-edge or to a defect mode in the band gap. The frequency of the down-converted signal can be tuned by intersecting two non co-linear laser sources. The polarizations are degenerate at normal incidence and have sub-THz down-conversion maximum. For aspecific sample geometry we show that by changing the angle of incidence of one tunable laser to 30 degrees the THz frequency is about11.5 THz for p-polarization and 3.5THz for s-polarization, since the angle-dependent transmission spectrum is different for p- and spolarizations.The peak conversion efficiency for both polarizations is enhanced by over two orders of magnitude. Finally we also introduce some preliminary experimental results which agree with the numerical results we present here.

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A Generalized case of Electromagnetic Scattering from a finite number of Ferromagnetic cylinders

Advanced Electromagnetics ◽

10.7716/aem.v4i3.264 ◽

2015 ◽

Vol 4 (3) ◽

pp. 8 ◽

Cited By ~ 1

Author(s):

T. Kumar ◽

N. Kalyanasundaram ◽

B. K. Lande

Keyword(s):

Finite Number ◽

Electromagnetic Scattering ◽

Scattered Field ◽

Near Field ◽

Scattering Problem ◽

Normal Incidence ◽

Generalized Solution ◽

Numerical Results ◽

Infinite Length ◽

Angle Of Incidence

A generalized solution of the scattering problem from an array containing a finite number of axially magnetized ferromagnetic cylinders of infinite length placed in free space is presented in this paper. The analysis is carried out by matching the tangential boundary conditions at the surface of each cylinder to find the unknown expansion coefficients of the scattered field. Planar arrays consist of a finite number of ferromagnetic microwires are considered to obtain the numerical results for TMz and TEz polarizations in terms of the variation in scattered field components of the near field and scattering cross section (SCS) with respect to angle of incidence, radius of microwires, spacing among the microwires and operating frequency. For validation purpose, numerical results of the proposed analysis specialized for the case of single microwire and normal incidence for TMz polarization are compared with the results available in the literature for the specialized case and both are found to be matched completely.

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On resolving fine periodic microstructures in the optical microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153798 ◽

1989 ◽

Vol 47 ◽

pp. 364-365

Author(s):

W.S. Putnam ◽

C. Viney

Keyword(s):

Liquid Crystalline ◽

Numerical Aperture ◽

Polarized Light ◽

Normal Incidence ◽

Optical Microscope ◽

Angle Of Incidence ◽

Resolution Limit ◽

Crystalline Materials ◽

Periodic Microstructures ◽

Liquid Crystalline Materials

Many sheared liquid crystalline materials (fibers, films and moldings) exhibit a fine banded microstructure when observed in the polarized light microscope. In some cases, for example Kevlar® fiber, the periodicity is close to the resolution limit of even the highest numerical aperture objectives. The periodic microstructure reflects a non-uniform alignment of the constituent molecules, and consequently is an indication that the mechanical properties will be less than optimal. Thus it is necessary to obtain quality micrographs for characterization, which in turn requires that fine detail should contribute significantly to image formation.It is textbook knowledge that the resolution achievable with a given microscope objective (numerical aperture NA) and a given wavelength of light (λ) increases as the angle of incidence of light at the specimen surface is increased. Stated in terms of the Abbe resolution criterion, resolution improves from λ/NA to λ/2NA with increasing departure from normal incidence.

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Carbon isotopomers measurement using mid-IR tunable laser sources

Isotopes in Environmental and Health Studies ◽

10.1080/10256010500384325 ◽

2005 ◽

Vol 41 (4) ◽

pp. 293-302 ◽

Cited By ~ 6

Author(s):

Damien Weidmann ◽

Chad B. Roller ◽

Clive Oppenheimer ◽

Alan Fried ◽

Frank K. Tittel

Keyword(s):

Tunable Laser ◽

Laser Sources

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A 10Gbps optical burst switching network incorporating ultra-fast (5ns) wavelength switched tunable laser sources

International Conference on Space Optics — ICSO 2008 ◽

10.1117/12.2308209 ◽

2017 ◽

Author(s):

Neil Ryan ◽

Michael Todd ◽

Adrian Lavin ◽

Brian Corbett ◽

Tom Farrell ◽

...

Keyword(s):

Optical Burst Switching ◽

Tunable Laser ◽

Switching Network ◽

Burst Switching ◽

Laser Sources ◽

Optical Burst Switching Network ◽

Optical Burst

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Second Harmonic Generation from Phase-Engineered Metasurfaces of Nanoprisms

Micromachines ◽

10.3390/mi11090848 ◽

2020 ◽

Vol 11 (9) ◽

pp. 848 ◽

Cited By ~ 1

Author(s):

Kanta Mochizuki ◽

Mako Sugiura ◽

Hirofumi Yogo ◽

Stefan Lundgaard ◽

Jingwen Hu ◽

...

Keyword(s):

Second Harmonic Generation ◽

Harmonic Generation ◽

Second Harmonic ◽

Field Enhancement ◽

Normal Incidence ◽

Electrical Field ◽

Fundamental Wavelength ◽

Reflectivity Spectra ◽

Lift Off ◽

Second Order Nonlinearity

Metasurfaces of gold (Au) nanoparticles on a SiO2-Si substrate were fabricated for the enhancement of second harmonic generation (SHG) using electron beam lithography and lift-off. Triangular Au nanoprisms which are non-centro-symmetric and support second-order nonlinearity were examined for SHG. The thickness of the SiO2 spacer is shown to be an effective parameter to tune for maximising SHG. Electrical field enhancement at the fundamental wavelength was shown to define the SHG intensity. Numerical modeling of light enhancement was verified by experimental measurements of SHG and reflectivity spectra at the normal incidence. At the plasmonic resonance, SHG is enhanced up to ∼3.5 × 103 times for the optimised conditions.

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Other Tunable Laser Sources

Field Guide to Lasers ◽

10.1117/3.767474.p102 ◽

2009 ◽

Author(s):

Rüdiger Paschotta

Keyword(s):

Tunable Laser ◽

Laser Sources

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Tunable broadband plasmonic field enhancement on a graphene surface using a normal-incidence plane wave at mid-infrared frequencies

Scientific Reports ◽

10.1038/srep11195 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 18

Author(s):

Tian Zhang ◽

Lin Chen ◽

Bing Wang ◽

Xun Li

Keyword(s):

Plane Wave ◽

Field Enhancement ◽

Normal Incidence ◽

Mid Infrared ◽

Graphene Surface ◽

Incidence Plane ◽

Infrared Frequencies

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Enhanced harmonic generation by propagation of two-color p-polarized laser beams in plasma

Laser and Particle Beams ◽

10.1017/s0263034617000052 ◽

2017 ◽

Vol 35 (1) ◽

pp. 182-189 ◽

Cited By ~ 4

Author(s):

E. Agrawal ◽

N.K. Verma ◽

P. Jha

Keyword(s):

Plasma Density ◽

Normal Incidence ◽

Laser Beams ◽

Angle Of Incidence ◽

Arbitrary Integer ◽

Third Harmonic ◽

Harmonic Radiation ◽

Fundamental Frequencies ◽

Order Of Magnitude ◽

Spatially Varying

AbstractA theoretical model is developed for studying the generation of third-harmonic radiation by the interaction of obliquely incident, two-color p-polarized laser beams with spatially varying plasma density. The ratio of the fundamental frequencies of the two laser beams are considered to be an arbitrary integer. The amplitude of harmonic radiation obtained by oblique incidence of two-color laser fields propagating in homogeneous plasma is enhanced in comparison with that obtained by normal incidence of two-color laser beams. The periodicity of the plasma density allows the harmonic radiation to be phase-matched, leading to further increase in the amplitude of phase-matched harmonic radiation by an order of magnitude. The amplitude of the generated harmonic radiation increases with the increase in angle of incidence.

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