Electro-optical Simulation of a-Si Thin-Film-Transistor Liquid Crystal Display Pixels

An analysis of an amorphous silicon (a-Si) thin-film-transistor liquid-crystal display (TFT-LCD) pixel is presented. The electro-optical model combines the electrical properties of the switching element and the optical performance of a twisted nematic (TN) liquid-crystal cell.Publicad

Visible WDM System Design for Multi-Gbit/s Transmission over SI-POF

This proceeding at: SPIE Photonics West 2015. IX Conference Broadband Access Communication Technologies (SPIE).In order to increase the data rates of Multi-Gbit/s links based on large core step index (SI) plastic optical fibers (POF), different modulation scenes have been proposed. Another option is to use multiple optical carriers for parallel transmission of communication channels over the same fiber. Some designs to reach data rates of 14.77 Gb/s in 50 m, with 4 channels have been developed by off line processing. In this work, designs to test the potential of real Multi- Gbit/s transmission systems using commercial products are reported. Special care in designing low insertion loss multiplexers and demultiplexers is carried out to allow for greener solutions in terms of power consumption.This work has been sponsored by the Spanish institutions Ministerio de Economía y Competitividad under project TEC2012-37983-C03-02, Comunidad de Madrid under grant S2013/MIT-2790.Publicad

Efficient Multiplexer/Demultiplexer for Visible WDM Transmission over SI-POF Technology

A five channel step index plastic optical fiber proposal for a multiplexer/demultiplexer having insertion losses (IL) of 2.9-4 dB, pass bandwidths at -3 dB > 30 nm, crosstalk attenuation >30 dB and size of similar to ~65 mm x 55 mm, is demonstrated. It is based on a reflective diffraction grating with blazed profile and an aspheric lens. The theoretical analysis presented is used to further reduce the system size to similar to ~37 mm x 30 mm and to increase the number of channels to 8 keeping ILs < 4.5 dB. Experimental results have good agreement with theoretical expectations.This work was supported by the Spanish Ministry of Economy and by Madrid region under Grants TEC2012-37983-C03-02 and P2013/MIT-2790.Publicad

Evaluation of Electro-Optic Behaviour of Chiral Smetic Liquid Crystals Dispalys with V-shaped response

In the last years, chiral smectic liquid crystals with V-shaped electro-optic response have been reported as one of the most promising technologies for display applications. In this work,some experiments have been made in order to check electrooptical performance of this kind of materials. Particularly, frequency dependence of optical response and memory effect in transmission have been analyzed. Microscopic observations of intermediate transmission levels and measurements of apparent tilt angle and response time have been also carried out

Broadband 1x2 liquid crystal optical switch with low thermal dependence

The proceeding at: 22nd International Conference on Plastic Optical Fibers (POF 2013), took place in 2013 September,11-13, in Armação dos Buzios, Rio de Janeiro, (Brasil). The event Web site at: http://www.pof2013.org.br/ .In this work, the optimized design of a broadband 1×2 liquid crystal (LC) optical switch (OS) is presented. The design is based on a polarization rotator (PR), which is composed of two nematic LC cells. The azimuth angle and thickness of each LC cell is obtained with a simple computational optimization approach, with performance comparable with more complex existing procedures. The LC-OS is capable to route, in a uniform way, optical signals in the visible spectral range (400 nm - 700 nm) with low thermal dependence in the range from 15ºC to 40ºC, making it ideal for wavelength division multiplexing applications in POF systems.This work has been sponsored by the Spanish Economy and Education Ministries through grants (Ref. TEC2012-37983-C03-02 and Ref. PRX12/00007).Publicad

Visible WDM system for real-time multi-Gb/s bidirectional transmission over 50-m SI-POF

We report a 2 Gb/s bidirectional real-time data transmission with bit error rate (BER) < 1 x 10(-10) in a 50 m step-index polymer optical fiber link. The system is able to transmit 5 Gb/s using five channels. The system performance is tested using the most restrictive channels with the shortest and longest wavelengths in a real-time Ethernet link. The implementation takes an advantage of the PAM-16 modulation spectral efficiency and low loss multiplexers and demultiplexers, which provide an enhanced link power budget. The optical power per transmitted bit considering the BER implication for TCP/IP networks throughput is below 5.8 pJ/b. This is due to the low insertion losses <4 dB, in each five-channel multiplexer and demultiplexer.This work was supported in part by the Spanish Ministry of Economy under Grants TEC2012-37983-C03-02 and TEC2015-63826-C3-2-R, and in part by Madrid Region under Grant S2013/MIT-2790

Optical router for optical fiber sensor networks based on a liquid crystal cell

Optical fiber sensor networks are evolving rapidly. They are used because of the inert nature of optical fibers allowing no electromagnetic interference and safe applications in inflammable atmospheres; other relevant characteristics are their low weights and wide bandwidths as a transmission medium. In any case, it is very interesting to have specific components such as optical routers for selecting a certain path in a network with no optical to electrical and electrical to optical conversions. In this paper, we propose an all-optical router based on liquid crystals, polarizers, and a spatial split polarization beam splitter. The implemented device is designed to operate with visible light and it has been tested with plastic optical fibers. It has a crosstalk of 14 dB between selected ON channels and nonoperative OFF channels and 11-dB insertion losses. An average switch time of 100 ms is measured. The device checks the optical power level in each channel and, in case of failure, automatically switches to an operative channel while an alarm is activated.Publicad

Electro-optic system for online light transmission control of polymer-dispersed liquid crystal windows

Polymer-dispersed liquid crystals (PDLCs) are formed by micro droplets of liquid crystal embedded in a flexible matrix and sandwiched between transparent electrodes. Large area units (several square meters) can be easily prepared. Opaque, transparent, and intermediate light transmission states can be achieved by applying appropriate electric fields These features allow their use in active windows for illumination, greenhouse regulation, and privacy, both on buildings and vehicles. An electro-optic system based on a micro controlled driver was implemented for on-line control of PDLC windows. The system may self regulate daylight or may be used as remote control.Publicad

Diffraction grating-based demultiplexers for SI-POF networks

The proceeding at: 22nd International Conference on Plastic Optical Fibers (POF 2013), took place in 2013 September,11-13, in Armação dos Buzios, Rio de Janeiro, (Brasil). The event Web site at: http://www.pof2013.org.br/ .In this paper, the possibility of implementing low-loss demultiplexer devices based on diffractive elements for SI-POF networks is studied. Theoretical and experimental analyses of three different diffractive setups are reported. It is also presented a 3-channel demultiplexer proposal, based on a transmission diffraction grating, with experimental insertion loss from 3.6dB to 5.8dB and adjacent channel crosstalk from −16.4dB to −28.6dB. This proposal presents low losses and low crosstalk, and it is very easy to implement in a compact reflective setup.This work has been sponsored by Ministerio de Economia y Competitividad (TEC2012-37983-C03-02) and Ministerio de Educacion, Cultura y Deportes (PRX12/00007),Publicad

Demonstration of a Data Transmission system With Visible Wavelength Division Multiplexing at 3-Gbit/s over 50-m of Plastic Optical Fiber

In this paper, a real-time data communication system based on a step-index polymer optical fiber (SI-POF) link of 50 m and a 3-channel visible wavelength division multiplexing (visible WDM) scheme is demonstrated. Special care on implementing low insertion loss multiplexers/demultiplexers is carried out to allow for greener solutions in terms of power consumption. The system performance has been experimentally tested using the first and last channels of the 3-channel available grid. The results show that the system can establish a real-time link with connection speed of up to 2 Gb/s with bit error rate <1×10-10 over 50 m of SI-POF, and having the potential for expanding its data transmission speed up to 3 Gb/s.This work has been sponsored by the Spanish institutions Ministerio de Economía y Competitividad under project TEC2012–37983–C03–02, Comunidad de Madrid under grant S2013/MIT–2790