Microwave variable delay line using dual-frequency switching-mode liquid crystal

Kuki, Takao; Fujikake, Hideo; Nomoto, Toshihiro

doi:10.1109/tmtt.2002.804510

Cited by 96 publications

(48 citation statements)

References 9 publications

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“…the diffusive Equations (15) and (27), one can obtain similar fast switching effect with the use of short intense laser induced thermal effect. From Equations (29)- (31), the interaction-time-dependent effective nonlinear index coefficient is similarly given in the form:…”

Section: Laser Induced Thermal-order Parameter Changes In Nlc For Ultmentioning

confidence: 91%

“…Figures 2(c)-(d), to millimeter-or bulkier microwave devices for tunable -delay line, -phase shifter, -wavelength selector and beam steering devices [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], to name a few. Nematic liquid crystals are uni-axial, characterized by refractive indices n and the n ⊥ , for light polarization parallel and orthogonal to the director axis, respectively.…”

Section: F Figures 2(a)-(b)mentioning

confidence: 99%

“…In absorbing NLC, or NLC's containing photo-excitable dopants, an impinging laser would create a temperature (ΔT ) change that is described by the following equation [2,3,68]: (27) Here C p is the specific heats, λ T the thermal conductivity, ρ 0 the unperturbed density of the liquid crystal, α the absorption constant, and I op the optical intensity. ΔT in turns gives rise to a change in the order parameter and consequently an index/birefringence change of the NLC.…”

Section: Laser Induced Thermal and Order Parameter Changesmentioning

confidence: 99%

See 2 more Smart Citations

MULTIPLE TIME SCALES OPTICAL NONLINEARITIES OF LIQUID CRYSTALS FOR OPTICAL-TERAHERTZ-MICROWAVE APPLICATIONS (Invited Review)

Khoo¹,

Zhao²

2014

PIER

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Abstract-We provide a critical account of the dynamics of laser induced refractive index changing mechanisms in nematic liquid crystals which may be useful for all-optical switching and modulation applications in the visible as well as the Terahertz and long-wavelength regime. In particular, the magnitude and response times of optical Kerr effects associated with director axis reorientation, thermal and order parameter changes, coupled flow-reorientation effects and individual molecular electronic responses are thoroughly investigated and documented, along with exemplary experimental demonstrations. Emphases are placed on identifying parameter sets that will enable all-optical switching with much faster response times compared to their conventional electro-optics counterparts.

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Section: Laser Induced Thermal-order Parameter Changes In Nlc For Ultmentioning

confidence: 91%

Section: F Figures 2(a)-(b)mentioning

confidence: 99%

Section: Laser Induced Thermal and Order Parameter Changesmentioning

confidence: 99%

See 1 more Smart Citation

MULTIPLE TIME SCALES OPTICAL NONLINEARITIES OF LIQUID CRYSTALS FOR OPTICAL-TERAHERTZ-MICROWAVE APPLICATIONS (Invited Review)

Khoo¹,

Zhao²

2014

PIER

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“…Recent advances in microwave and millimeter-wave devices which exploit the dielectric anisotropy of liquid crystal (LC) materials have mainly been accomplished using planar waveguide structures [1,2] and quasi-optical structures [3,4,5]. In the former, a microstrip delay line using dual-frequency switching mode LC [1] and a microstrip phase shifter using polymer-dispersed LC [2] have been developed to improve insertion loss and time response.…”

Section: Introductionmentioning

confidence: 99%

“…In the former, a microstrip delay line using dual-frequency switching mode LC [1] and a microstrip phase shifter using polymer-dispersed LC [2] have been developed to improve insertion loss and time response. Quasi-optical devices utilizing LC materials have been proposed to realize reconfigurable optics [3,4] and to generate an electronically tunable bandpass filter [5].…”

Section: Introductionmentioning

confidence: 99%

A millimeter-wave quasi-optical grid phase shifter using liquid crystal

Nozokido

Maede

Miyasaka

et al. 2010

IEICE Electron. Express

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Abstract:A new type of millimeter-wave quasi-optical variable phase shifter which exploits the dielectric anisotropy of liquid crystal (LC) materials is presented. The device is operated in transmission mode and consists of inductive and capacitive metal grids, each patterned on a dielectric substrate, which are separated by a thin layer of LC. The grids together with the LC form a parallel resonant circuit. Prototype devices with a 25-μm-thick LC layer for use at a millimeterwave frequency of 50 GHz were designed and fabricated. Experiments performed at U-band frequencies show that a phase shift of 7.8 • is obtained with a low insertion loss of ∼ 0.6 dB at the resonant frequency by applying a control signal of 20 V. Good time response for the device is demonstrated. It is suggested that the phase shift attainable with the device can be further enhanced by using LC materials with larger dielectric anisotropy and/or thinner dielectric substrates. Keywords: grid structures, liquid crystals, millimeter wave, phase shifters, quasi optics Classification: Microwave and millimeter wave devices, circuits, and systems References

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Liquid Crystals for Advanced Smart Devices with Microwave and Millimeter‐Wave Applications: Recent Progress for Next‐Generation Communications

Choi

Park

et al. 2023

Advanced Materials

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Liquid crystals (LCs) technology have a well‐established history of applications in visible light, particularly in the display industry. However, with the rapid growth in communication technology, LCs have become a topic of current interest for high‐frequency microwave (MW) and millimeter‐wave (mmWave) applications due to promising characteristics such as tunability, continuous tuning, low losses, and price compatibility. To improve the performance of future communication technology using LCs, it is not sufficient only with the perspective of radio‐frequency (RF) technology. Therefore, it is imperative to understand not only the novel structural designs and optimization of MW engineering but also the perspective of materials engineering when implementing advanced RF devices with maximum performance for next‐generation satellite and terrestrial communication. Herein, based on advanced nematic LCs, polymer‐modified LCs, dual‐frequency LCs, and photo‐reactive LCs, this article summarizes and examines the modulation principles and key research directions for the design strategies of LCs for advanced smart RF devices with improved driving performance and novel functionality. Furthermore, the challenges in development of state‐of‐the‐art smart RF devices that use LCs are discussed.

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Microwave variable delay line using dual-frequency switching-mode liquid crystal

Cited by 96 publications

References 9 publications

MULTIPLE TIME SCALES OPTICAL NONLINEARITIES OF LIQUID CRYSTALS FOR OPTICAL-TERAHERTZ-MICROWAVE APPLICATIONS (Invited Review)

MULTIPLE TIME SCALES OPTICAL NONLINEARITIES OF LIQUID CRYSTALS FOR OPTICAL-TERAHERTZ-MICROWAVE APPLICATIONS (Invited Review)

A millimeter-wave quasi-optical grid phase shifter using liquid crystal

Liquid Crystals for Advanced Smart Devices with Microwave and Millimeter‐Wave Applications: Recent Progress for Next‐Generation Communications

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