scholarly journals Layered THz waveguides for SPPs, filter and sensor applications

2019 ◽  
Vol 48 (4) ◽  
pp. 567-581 ◽  
Author(s):  
Jiamin Liu ◽  
Zia Ullah Khan ◽  
Siamak Sarjoghian
Keyword(s):  
Refractive Index ◽  
Layered Structure ◽  
Dielectric Slab ◽  
Low Loss ◽  
Sensor Applications ◽  
Te Mode ◽  
Tm Mode ◽  
Mode Characteristics ◽  
Plasmon Polaritons ◽  
Thz Waveguides

Abstract Theory of five kinds of layered structure THz waveguides is presented. In these waveguides, the modified and hybrid THz surface plasmon-polaritons (SPPs) are researched in detail. On these modes, the effects of material in each layer are discussed. The anti-resonant reflecting mechanism is also discussed in these waveguides. The mode characteristics of both TM mode and TE mode are analyzed for guiding TM mode with low loss and TE modes with huge loss in one waveguide: the TE modes filter application is put forward. The mode characteristics for one waveguide have useful sensor applications: for TE1 mode, we find that the low cut-off frequency has a sensitivity (S) to the refractive index of the dielectric slab. The highest S can be 666.7 GHz/RIU when n2 = 1.5, w = 0 and t = 0.1 mm. We believe these results are very useful for designing practical THz devices for SPPs, filter and sensor applications.

INVESTIGATION OF MATERIAL GAIN OF In0.90Ga0.10As0.59P0.41/InP LASING NANO-HETEROSTRUCTURE

2014 ◽  
Vol 28 (10) ◽  
pp. 1450068 ◽  
Author(s):  
RASHMI YADAV ◽  
PYARE LAL ◽  
F. RAHMAN ◽  
S. DALELA ◽  
P. A. ALVI
Keyword(s):  
Refractive Index ◽  
Communication Systems ◽  
Refractive Index Change ◽  
Single Quantum Well ◽  
Lasing Wavelength ◽  
Index Change ◽  
Te Mode ◽  
Tm Mode ◽  
Material Gain ◽  
Valence Bands

In this paper, we have proposed a step separate confinement heterostructure (SCH) based lasing nano-heterostructure In 0.90 Ga 0.10 As 0.59 P 0.41/ InP consisting of single quantum well (SQW) and investigated material gain theoretically within TE and TM polarization modes. In addition, the quasi Fermi levels in the conduction and valence bands along with other lasing characteristics like anti-guiding factor, refractive index change with carrier density and differential gain have also been investigated and reported. Moreover, the behavior of quasi Fermi levels in respective bands has also been correlated with the material gain. Strain dependent study on material gain and refractive index change has also been reported. Interestingly, strain has been reported to play a very important role in shifting the lasing wavelength of TE mode to TM mode. The results investigated in the work suggest that the proposed unstrained nano-heterostructure is very suitable as a source for optical fiber based communication systems due to its lasing wavelengths achieved at ~1.35 μm within TM mode, while ~1.40 μm within TE mode.

Multilayer porous waveguide for microwave low-loss applications

2011 ◽  
Vol 3 (4) ◽  
pp. 459-463
Author(s):  
Ebrahim Mortazy ◽  
Alireza Hassani ◽  
Francois Legare ◽  
Ke Wu ◽  
Mohamed Chaker
Keyword(s):  
Transmission Lines ◽  
Dielectric Waveguide ◽  
Low Loss ◽  
Air Gaps ◽  
Dielectric Substrates ◽  
Te Mode ◽  
Tm Mode ◽  
Rectangular Dielectric Waveguide ◽  
Electrical Permittivity ◽  
Lower Loss

A novel waveguide called multilayer porous waveguide (MPW) is proposed as microwave low-loss transmission lines. MPW is a fully rectangular dielectric waveguide composed of several periodically rectangular air gaps in a bulk dielectric that can be easily formed by placing several dielectric substrates in interval with air gaps. The loss and propagating characteristics of both TE and TM modes in MPW are studied. The TE mode confined in the air gaps has a lower loss than the TM mode spread out in air gaps and dielectric; however, the loss of TM mode is still less than that of conventional microwave waveguides. Finally, MPW is an artificial material with desirable electrical permittivity and loss that can be used in structure of conventional waveguides.

scholarly journals Optical Sensitivity of Waveguides Inscribed in Nanoporous Silicate Framework

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 123
Author(s):  
Zhong Lijing ◽  
Roman A. Zakoldaev ◽  
Maksim M. Sergeev ◽  
Andrey B. Petrov ◽  
Vadim P. Veiko ◽  
...  
Keyword(s):  
Refractive Index ◽  
Near Field ◽  
Experimental Studies ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Direct Writing ◽  
Sensor Applications ◽  
Refractive Index Contrast ◽  
Optical Sensitivity ◽  
Index Contrast

Laser direct writing technique in glass is a powerful tool for various waveguides’ fabrication that highly develop the element base for designing photonic devices. We apply this technique to fabricate waveguides in porous glass (PG). Nanoporous optical materials for the inscription can elevate the sensing ability of such waveguides to higher standards. The waveguides were fabricated by a single-scan approach with femtosecond laser pulses in the densification mode, which resulted in the formation of a core and cladding. Experimental studies revealed three types of waveguides and quantified the refractive index contrast (up to Δn = 1.2·10−2) accompanied with ~1.2 dB/cm insertion losses. The waveguides demonstrated the sensitivity to small objects captured by the nanoporous framework. We noticed that the deposited ethanol molecules (3 µL) on the PG surface influence the waveguide optical properties indicating the penetration of the molecule to its cladding. Continuous monitoring of the output near field intensity distribution allowed us to determine the response time (6 s) of the waveguide buried at 400 µm below the glass surface. We found that the minimum distinguishable change of the refractive index contrast is 2 × 10−4. The results obtained pave the way to consider the waveguides inscribed into PG as primary transducers for sensor applications.

scholarly journals Influence of Rugate Filters on the Spectral Manifestation of Tamm Plasmon Polaritons

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1282
Author(s):  
Victor Reshetnyak ◽  
Igor Pinkevych ◽  
Timothy Bunning ◽  
Dean Evans
Keyword(s):  
Refractive Index ◽  
Band Gap ◽  
External Medium ◽  
Metal Layer ◽  
Refractive Index Profile ◽  
Spectral Position ◽  
Index Profile ◽  
Reflection And Transmission ◽  
Rugate Filter ◽  
Plasmon Polaritons

This study theoretically investigated light reflection and transmission in a system composed of a thin metal layer (Ag) adjacent to a rugate filter (RF) having a harmonic refractive index profile. Narrow dips in reflectance and peaks in transmittance in the RF band gap were obtained due to the excitation of a Tamm plasmon polariton (TPP) at the Ag–RF interface. It is shown that the spectral position and magnitude of the TPP dips/peaks in the RF band gap depend on the harmonic profile parameters of the RF refractive index, the metal layer thickness, and the external medium refractive index. The obtained dependences for reflectance and transmittance allow selecting parameters of the system which can be optimized for various applications.

scholarly journals Low-loss ARROW waveguide with rectangular hollow core and rectangular low-density polyethylene/air reflectors for terahertz waves

2018 ◽  
Vol 27 (03) ◽  
pp. 1850029 ◽  
Author(s):  
Henri P. Uranus ◽  
B. M. A. Rahman
Keyword(s):  
Refractive Index ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Hollow Core ◽  
Terahertz Waves ◽  
Low Loss ◽  
Leakage Loss ◽  
Crystal Fiber ◽  
Air Core ◽  
The Waves

Designing low-loss waveguides for terahertz waves is challenging as most materials are very lossy in this frequency band. Most scientists simply consider transmitting the waves through low-loss air, which however also has its own difficulties as index-guiding is not possible. In this paper, we report on the design of low-loss waveguides for terahertz waves and associated results by using a finite element leaky mode solver. These results show that waveguides designed using ARROW (anti-resonant reflecting optical waveguide) approach yield a low combined absorption and leakage loss down to only 0.05[Formula: see text]dB/cm for the q-TE[Formula: see text] fundamental mode using realistic values of refractive index at 1 THz operating frequency. The structure employs rectangular hollow-core and low-density polyethylene/air anti-resonant reflecting bilayers, which can be easily fabricated. These results are compared with those of other structures, i.e., a photonic crystal fiber-like structures using the same materials with rectangular holes, which is shown to give a higher loss of 3[Formula: see text]dB/cm and a suspended air-core waveguide with TOPAS vein offering a loss of 1[Formula: see text]dB/cm.

Integrated (Pb,La)(Zr,Ti)O3 Heterostructure Waveguide Devices Fabricated by Solid-Phase Epitaxy

1999 ◽  
Vol 597 ◽  
Author(s):  
K. Nashimoto ◽  
S. Nakamura ◽  
H. Moriyama ◽  
K. Haga ◽  
M. Watanabe ◽  
...  
Keyword(s):  
Low Voltage ◽  
Solid Phase ◽  
Wet Etching ◽  
Propagation Loss ◽  
Beam Deflection ◽  
Solid Phase Epitaxy ◽  
Te Mode ◽  
Tm Mode ◽  
Electro Optic ◽  
Channel Waveguides

AbstractHeterostructures of a Pb(Zr,Ti)O3 (PZT) waveguide/(Pb,La)(Zr,Ti)O3 (PLZT) system buffer layer were grown on a Nb-doped SrTiO3 (Nb:ST) substrate by solid-phase epitaxy. The propagation loss in the PLZT heterostructure waveguides was on the order of I dB/cm. An electro-optic beam deflection device with an ITO prism electrode on the surface of the PLZT heterostructure waveguide presented efficient deflection of the coupled laser beam by applying a voltage between the electrode and the substrate. A beam deflection greater than 10 mrad at 5 V and frequency response as fast as 13 MHz were observed. An apparent electro-optic coefficient as large as 39 pmJV was estimated from the deflection characteristics for the TE mode and TM mode suggesting the polarization independent nature of the PZT waveguide. For integrating the electrooptic PLZT heterostructure waveguides, channel waveguides were fabricated in the PZT waveguides using a simple wet-etching process. Based on a low-voltage drive structure, lowloss waveguide process, and fine patterning process, a fabricated digital matrix switch showed a – 10 dB cross-talk at a voltage as low as 7.5 V.

Modelling of semiconductor rib wave guides by a finite difference method

1991 ◽  
Vol 69 (3-4) ◽  
pp. 512-519 ◽  
Author(s):  
A. Delâge
Keyword(s):  
Refractive Index ◽  
Boundary Conditions ◽  
Abrupt Change ◽  
Multiple Quantum Well ◽  
External Boundary ◽  
Multiple Quantum ◽  
Scalar Wave ◽  
Accurate Evaluation ◽  
Wave Guides ◽  
Mode Characteristics

The method of finite differences is used to solve the scalar wave equation for semiconductor rib wave guides. Boundary conditions derived from continuity relations are applied between regions of different refractive index, allowing more accurate evaluation of the propagation constants for ideal cases of abrupt change in the index. Also appropriate external boundary conditions alleviate the inaccuracy generally introduced by setting the field equal to zero on the external limit of the mesh. Our results agree with various other techniques when applied to typical guiding structures. As an example, we model a multiple-quantum-well structure by using an equivalent layered structure. Mode characteristics and confinement factors obtained by the method are of interest in understanding the behaviour of the lasers and modulators fabricated in our laboratory.

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