| 1. |
- Fazio, V. S. U., et al.
(författare)
-
Enhanced phase-matched second-harmonic generation in a ferroelectric liquid crystal waveguide
- 2001
-
Ingår i: Molecular Crystals and Liquid Crystals Science and Technology. - 1058-725X. ; 368, s. 4061-4070
-
Tidskriftsartikel (refereegranskat)abstract
- A binary mixture of crosslinkable ferroelectric liquid crystals (FLCs) was used for the design of a channel waveguide. The liquid crystal was aligned in layers parallel to the glass plates (homeotropic) in a sandwich geometry and then the arrangement was permanently fixed by photopolymerization which yielded a polar network possessing a high thermal and mechanical stability. The linear and nonlinear optical properties have been measured and all four independent components of the nonlinear susceptibility tensor d have been determined. The off-resonant d-coefficients are remarkably high and comparable to those of the best known inorganic materials. Phase-matching was achieved by taking advantage of the modal dispersion of the waveguide. A reversal of sign of chi ((2)) at the nodal plane of the electric field distribution of the first-order mode was needed to maximize the overlap. integral between the fundamental and the second-harmonic (SH) light. In samples with chi ((2)) inversion the SH Signal was 1000 larger that in samples without chi ((2)) inversion.
|
|
| 2. |
- Fazio, V. S. U., et al.
(författare)
-
Nonlinear optical properties of a channel waveguide produced with crosslinkable ferroelectric liquid crystals
- 2000
-
Ingår i: The European Physical Journal E Soft matter. - : Springer Science and Business Media LLC. - 1292-8941 .- 1292-895X. ; 3:3, s. 245-251
-
Tidskriftsartikel (refereegranskat)abstract
- A binary mixture of ferroelectric liquid crystals (FLCs) was used for the design of a channel waveguide. The FLCs possess two important functionalities: a chromophore with a high hyperpolarizability beta and photoreactive groups. The smectic liquid crystal is aligned in layers parallel to the glass plates in a sandwich geometry. This alignment offers several advantages, such as that moderate electric fields are sufficient to achieve a high degree of polar order. The arrangement was then permanently fixed by photopolymerization which yielded a polar network possessing a high thermal and mechanical stability which did not show any sign of degradation within the monitored period of several months. The linear and nonlinear optical properties have been measured and all four independent components of the nonlinear susceptibility tensor (d) over bar have been determined. The off-resonant d-coefficients are remarkably high and comparable to those of the best known inorganic materials. The alignment led to an inherent channel waveguide for p-polarized light without additional preparation steps. The photopolymerization did not induce scattering sites in the waveguide and the normalized losses were less than 2 dB/cm. The material offers a great potential for the design of nonlinear optical devices such as frequency doublers of low-power laser diodes.
|
|
| 3. |
- Fazio, V. S. U., et al.
(författare)
-
Phase-matched second-harmonic generation in a ferroelectric liquid crystal waveguide
- 2000
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 77:3, s. 319-321
-
Tidskriftsartikel (refereegranskat)abstract
- True phase-matched second-harmonic generation in a waveguide of crosslinkable ferroelectric liquid crystals is demonstrated. These materials allow the formation of macroscopically polar structures whose order can be frozen by photopolymerization. Homeotropic alignment was chosen which offers decisive advantages compared to other geometries. All parameters contributing to the conversion efficiency are maximized by deliberately controlling the supramolecular arrangement. The system has the potential to achieve practical level of performances as a frequency doubler for low power laser-diodes.
|
|
