In the present work, the hyper-branched (HB) polymer is utilized as a host material to efficiently incorporate the
nonlinear optical chromophore. The HB polymer and toluene diisocyanate (2, 4-TDI) formed 3-D networks, and the
typical FTC or CF3-Ph-FTC chromophores were introduced to investigate the electro-optic activity (r<sub>33</sub>). At the same
time, poling behavior of NLO chromophores in the traditional poly methyl methacrylate (PMMA) and Poly MMA-MOI
side-chain polymers were also included in this work for comparison. For FTC doped composites, the r<sub>33</sub> reached over 80
pm/V in 3-D network matrix, while the value of r<sub>33</sub> maximized at about 45 pm/V in traditional PMMA host and 70 pm/V
in side-chain polymers. In addition, the measurement of poling process, poling efficiency, and thermal stability for the
real application were also investigated.
We investigated the enhancement of the voltage-induced phase difference by embedding an electro-optic (EO) polymer
into a reflective planar microcavity in a reflection ellipsometric configuration. We fabricated the microcavity with
efficient light localization in the EO polymer and evaluated the resultant enhancement of voltage-induced phasedifference
between s- and p-polarized components. We obtained 48 times larger phase-difference than that for the EO
polymer only. The enhancement was attributed to the polarization-dependent local field effect for oblique incidence.
An ultra-compact Mach-Zehnder (MZ) electro-optic (EO) modulator composed of nanoscale metal gap waveguides has
been numerically demonstrated. Propagations of surface plasmon polaritons (SPPs) in nano-size channels and their EO
modulations are investigated by the finite difference time domain (FDTD) method considering the Lorentz-Drude (LD)
model. The half-wave voltage (Vπ) of the resulting MZ modulator for push-pull operation is 1.73 V using the
interference arm with a sub-micron length (500 nm).
We have successfully demonstrated enhancement of the two-photon excited fluorescence (TPEF) in a highly nonlinear
optical polymer two-dimensional (2D) photonic crystal (PhC) waveguide, arising from resonant coupling between the
external laser field and a photonic band mode. Moreover, we directly determine the experimental photonic band
dispersion structure of waveguiding modes under the light line in a 2D PhC waveguide by using angle-resolved
attenuated total reflection spectroscopy. Resonance coupling between the external evanescent wave from total reflection
within the prism and the waveguiding modes in the 2D PhC provides clear information on individual band components
by resolving the angle (i.e., wave vector <i>k</i>) and photon energy. The experimentally determined photonic band structure
is essential for understanding the novel light propagation and nonlinear optical properties of PhC systems. Good
agreement was obtained between the TPEF enhancements and features of the photonic band structure, indicating that
active manipulation of these nonlinear TPE processes is a realistic possibility through engineering the band dispersion
and band group velocity characteristics. Future work in this direction should lead to dramatic improvements in the
performance of TPE applications.
Organic nonlinear optical (NLO) materials have attracted much interest for their potential applications over the past two
decades mainly because of their faster electronic response and larger optical nonlinearities than the conventional
inorganic materials. Especially, electro-optic (EO) polymers have been promising candidates for fast and broadband EO
modulators as a result of the development of the 2nd-order NLO chromophore. In this manuscript, we report fabrication
and design of one dimensional (1D) polymeric photonic crystals (PCs) to additionally enhance the optical nonlinearities
of the organic NLO materials. We fabricated polymeric high-reflection mirrors for 1D PCs by a simple alternatively
spin-coating two polymers under control of their optical thickness, in which a novel polymer was applied to the higher
refractive index layer. We also designed defect-mode 1D polymeric PC for effective light-localization in the defect layer
and discussed their effect for enhancement of the 2nd-order optical nonlinearities.
We report a technique for embedding submicrometer-scale polymer defects in the interior of self-organized
two-dimensional photonic crystals by controlled two-photon induced polymerization. They demonstrate a rapid and
flexible technique for optical fabrication by creating polymer features in registration with a photonic crystal. Polymer
features were embedded in individual pores with a diameter of 100 nm by controlled photopolymerization under
confocal optical microscopy. Spectrum measurements confirm that the photonic stop band limits the light propagation
of the emission from the embedded polymer structures.
The growth and overlap of research in the fields of photonic crystals (PhCs) and nonlinear optics should lead to new exciting, active functions and high-efficiency nonlinear optical applications because nonlinear optical effects in PhCs may allow for significant advances in various optical processes by using resonantly stored light and anomalous band dispersions, in combination with nonlinear optical host materials. To show the experimental and theoretical evidences of great potentials of the nonlinear PhCs for the realization of the high-efficient and very compact nonlinear optical devices and applications, we have examined the typical second- and third-order nonlinear optical responses and the photonic band structure of the nonlinear two-dimensional (2D) PhC waveguides. We have demonstrated for the first time the second harmonic generation (SHG), the sum-frequency mixing (SFM) in the ultraviolet (UV) region, and the strong enhancement of the SHG intensity originating from the photonic band resonance in this waveguide. Moreover, by probing the nonlinear optical changes of the band resonances in angle-resolved reflectivity,we have shown direct evidence that the nonlinear optical changes arising from modifications of the photonic bands by purely optical means are dominated by the dispersion nature and the group velocity of the photonic bands, which are essential for the realization of desirable nonlinear applications, such as practical all-optical switching devices with very low operational power and ultra-small dimensions. These results agree well with the bhavior predicted from band structures, indicating that the design of nonlinear optical properties of material systems is realistically possible by band dispersion and group velocity engineering.