• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 39
  • 15
  • 13
  • 10
  • 3
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 100
  • 100
  • 29
  • 26
  • 26
  • 20
  • 14
  • 14
  • 14
  • 13
  • 13
  • 12
  • 12
  • 12
  • 11
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthesis, decomposition and phase homogeneity of PLZT powder and microstructural evolution on densification

Akbas, Mehmet Ali January 1995 (has links)
No description available.
2

Electric field birefringence and light scattering of polydisperse colloids

Watson, Rupert M. J. January 1992 (has links)
No description available.
3

An optical sensor for the non-interactive detection of weak electric fields

Paton, C. R. January 1986 (has links)
No description available.
4

Novel optical fibres and their applications

Li, L. January 1989 (has links)
No description available.
5

Analysis of change in surface form using digital image processing

Koukash, M. B. Q. S. January 1987 (has links)
No description available.
6

Electro-Optic Polymers: Materials and Devices

DeRose, Christopher Todd January 2009 (has links)
Electro-optic (EO) polymers are an attractive alternative to inorganic nonlinear materials. EO polymers with a Pockel's coefficient, r33, greater than 320 pm/V have been recently demonstrated. In addition to their high EO activity, EO polymers have the additional benefit that their dielectric constants at optical and millimeter wave frequencies are closely matched which allow for bandwidths which are limited only by the resistive losses of traveling wave electrodes. The amorphous nature of the host polymer makes heterogeneous integration of the materials on any substrate possible. The devices which will have the most immediate impact based on these recent materials developments are EO waveguide modulators. Performance benchmarks of less than 6 dB insertion loss, sub-volt Vpi and greater than 100 GHz bandwidth have been achieved separately however, the challenge of achieving all of these benchmarks in a single device has not yet been met.The aim of this dissertation is to optimize passive materials to achieve efficient in device poling of EO polymers, optimize the chromophore loading of the active polymers and to optimize waveguide modulators for device performance within a particular system, analog RF photonic links. These optimizations were done by defining figures of merit for the materials and modulators. This research strategy has led to significant improvements in poling efficiency as well as modulators with record low insertion losses which maintain a low half-wave voltage; on the order of 1 - 2 Volts. Using this optimization strategy and state of the art EO polymers, devices which meet or surpass the benchmark performance values in all categories are expected in the near future.
7

Ferroelectric liquid crystal polymers

Verrall, Mark Andrew January 1999 (has links)
No description available.
8

Tunable erbium-doped fiber ring laser using an intra-cavity filter

Fadel, Hicham Joseph 15 November 2004 (has links)
Linear tuning the frequency of an erbium-doped fiber ring laser using both a Fabry-Perot filter and an electro-optic tunable filter has been experimentally demonstrated. The rate of frequency change is determined by monitoring the fringes produced by laser light transmitted through a fiber Fabry-Perot interferometer. The fiber ring laser has been tuned over a 50 nm spectral range when using the Fabry-Perot filter and a tuning rate of 16480 nm/s has been achieved. The spectral width of the laser is 0.049 nm and the nearest sidelobe to the main peak is more than 30 dB below the central lobe. When the electro-optic tunable filter is used, a spectral range of 11 nm is reached. The spectral width is 2.33 nm and is in close agreement with the filter theoretical results. The sidelobe to main peak difference is around 13 dB.
9

Tunable erbium-doped fiber ring laser using an intra-cavity filter

Fadel, Hicham Joseph 15 November 2004 (has links)
Linear tuning the frequency of an erbium-doped fiber ring laser using both a Fabry-Perot filter and an electro-optic tunable filter has been experimentally demonstrated. The rate of frequency change is determined by monitoring the fringes produced by laser light transmitted through a fiber Fabry-Perot interferometer. The fiber ring laser has been tuned over a 50 nm spectral range when using the Fabry-Perot filter and a tuning rate of 16480 nm/s has been achieved. The spectral width of the laser is 0.049 nm and the nearest sidelobe to the main peak is more than 30 dB below the central lobe. When the electro-optic tunable filter is used, a spectral range of 11 nm is reached. The spectral width is 2.33 nm and is in close agreement with the filter theoretical results. The sidelobe to main peak difference is around 13 dB.
10

Programmable two-port polarization independent electro-optically tunable wavelength filter in lithium niobate

Ping, Yang 15 May 2009 (has links)
Programmable two-port polarization independent electro-optically wavelength tunable filters based on asymmetric Mach-Zehnder structure in LiNbO3 substrate have been developed for 1.55 µm application. The operation principle is based on Mach-Zehnder interference and TE↔TM polarization conversion. Fabrication parameters for channel waveguides, polarization converters and bandpass filters have been optimized. Straight channel waveguides 7 µm in width were produced by diffusing 1116 Å thick Ti into LiNbO3 substrate at 1035°C for 10 hours. Single mode guiding has been realized for both TE and TM polarization. Insertion loss of 2.9 dB for TE polarization input and 3.3 dB for TM polarization input were achieved on a 46 mm long sample. Single sideband programmable polarization mode converters were produced with 16 electrode sets, each containing 64 grating periods. Programmability was achieved by applying spatially periodic weighted independent voltages to interdigital electrode sets, and controlled electronically via a personal computer through a digital-to-analog converter array chip. Maximum conversion efficiency of more than 99% was realized for both TM→TE and TE→TM, and was observed at 1530.48 nm. Two-port polarization independent electro-optically tunable wavelength filters were produced based on the results obtained above. The 3 dB bandwidth is 1.1 nm and the nearest side lobes to the main transmission are down by about 9 dB for uniform coupling. Side lobes are reduced to about 20 dB below peak transmission after apodization, and the 3 dB bandwidths increased to ~ 1.3 nm as a result. Seven channels (channel -4, -2, -1, 0, +1, +2 and +4) were selectable by programming the voltages on each electrode set. Channel spacing is 1.1~1.2 nm. The tuning ranges from 1524.04 to 1533.56 nm. Fiber-to-fiber insertion loss of the filter at center frequency is 4.3 dB for TE input and 4.2 dB for TM input. The polarization dependent loss is < 0.5 dB for all selectable channels. The temporal response to a 21 V step change in applied voltages was measured to be 586 ns for the 10%-90% rise time and 2.308 µs for the 90%-10% fall time. This research work provides a convenient scheme for making programmable two-port tunable bandpass filters and ROADMs.

Page generated in 0.0536 seconds