Poly(aryleneethynylene)s: Syntheses, Properties, Structures, and Applications

Spiropyrans and Spirooxazines for Memories and Switches

A series of rigid microporous poly(aryleneethynylene) (PAE) networks was synthesized by Sonogashira−Hagihara coupling chemistry. PAEs with apparent Brunauer−Emmet−Teller surface areas of more than 1000 m2/g were produced. The materials were found to have very good chemical and thermal stability and retention of microporosity under a variety of conditions. It was shown that physical properties such as micropore size, surface area, and hydrogen uptake could be controlled in a “quantized” fashion by varying the monomer strut length, as for metal−organic and covalent organic frameworks, even though the networks were amorphous in nature. For the first time, it was demonstrated that these properties can also be fine-tuned in a continuous manner via statistical copolymerization of monomer struts with differing lengths. This provides an unprecedented degree of direct synthetic control over micropore properties in an organic network.

Synthetic Control of the Pore Dimension and Surface Area in Conjugated Microporous Polymer and Copolymer Networks

The principles and most-recent results of high-power THz generation through optical rectification using a tilted optical pulse front are described. Single-cycle THz pulses of multimicrojoule energies are generated at kHz repetition rates, and average THz power levels exceeding 1 mW can be generated at kHz-MHz repetition rates. Applications in nonlinear THz spectroscopy and THz coherent control are discussed.

Generation of high-power terahertz pulses by tilted-pulse-front excitation and their application possibilities

Cascading is the process by which the exchange of energy between optical beams interacting via second order nonlinearities (χ(2)) leads to various effects such as nonlinear phase shifts, the generation of new beams, all-optical transistor action, the formation of soliton-like (solitary) waves, etc. Here we review the fundamentals of the processes and discuss experimental verification of the effects and various related applications.

χ(2) cascading phenomena and their applications to all-optical signal processing, mode-locking, pulse compression and solitons

We show that the organic salt 4‐N,N‐dimethylamino‐4′‐N′‐methyl‐stilbazolium tosylate (DAST) is a very interesting material for electro‐optic applications in the near infrared. The electro‐optic coefficients, namely r111, r221, r331, r113, r223, and r333, were determined in the spectral range of 700 up to 1535 nm using optical samples cut from large high quality bulk crystals. DAST combines large electro‐optic coefficients, e.g., r111=77±8 pm/V at λ=800 nm and r111=47±8 pm/V at λ=1535 nm, with low dielectric constants, e.g., e1=5.2±0.4. This combination leads to large polarization‐optical coefficients.

Electro‐optic properties of the organic salt 4‐N,N‐dimethylamino‐4′‐N′‐methyl‐stilbazolium tosylate

Solid State Physics, ETH Zu ¨rich, CH-8093 Zurich, Switzerland~Received 31 May 2001; revised manuscript received 27 December 2001; published 26 November 2002!We use infrared spectroscopy and Raman scattering to show that molecular vibrations considerably contrib-ute to the linear electro-optic effect in the highly nonlinear optical organic crystal 4-N,N-dimethylamino-4

Infrared and Raman spectroscopy of the organic crystal DAST: Polarization dependence and contribution of molecular vibrations to the linear electro-optic effect

We show both theoretically and experimentally that the combined processes of optical rectification and the linear electro-optic effect lead to an effective nonlinear refractive index ${n}_{2}$ in noncentrosymmetric materials. This cascaded second-order nonlinear optical effect arises in addition to the well-known contribution due to second-harmonic generation and difference-frequency mixing and is of comparable magnitude. However, it has the advantage of a broad acceptance angle because no precise phase matching is needed. Experimental results in KNb${\mathrm{O}}_{3}$ crystals are presented.

Kerr Nonlinearity via Cascaded Optical Rectification and the Linear Electro-optic Effect.

Structure‐property relationships in nonlinear optical tetraethynylethenes

We present a simple method to measure the contribution from acoustic phonons to the linear electro-optic effect. A step voltage with a short rise time (600 ps) is applied to the sample, and the electro-optic response is measured in the time domain. For the organic salt 4-N, N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST), we obtained a negative contribution of r111a=-1.0±0.1 pm/V to the overall electro-optic coefficient of r111=48±5 pm/V λ=1535 nm. The electro-optic response was limited only by the rise time of the applied voltage, which corresponds to a frequency of 1 GHz.

R. Spreiter

Papers

Electro‐optic properties of the organic salt 4‐N,N‐dimethylamino‐4′‐N′‐methyl‐stilbazolium tosylate

Infrared and Raman spectroscopy of the organic crystal DAST: Polarization dependence and contribution of molecular vibrations to the linear electro-optic effect

Kerr Nonlinearity via Cascaded Optical Rectification and the Linear Electro-optic Effect.

Structure‐property relationships in nonlinear optical tetraethynylethenes

High-frequency response and acoustic phonon contribution of the linear electro-optic effect in DAST.