Polydiacetylene , nonlinear optics

The above conclusions introduce intrinsic limitations to the use of the ID conjugated systems in nonlinear optical devices. Although these may benefit (38) from the high nonlinearities,their response speed will be limited by the motion of such defects. These may also be formed by other means than light and this will clearly have implications on photoelastic, pyroelectric and piezoelectric effects as well. We point out that materials like polydiacetylenes may show appreciable quadrupolar pyroelectric effect (39). 

The nonlinear optical properties of novel, soluble polydiacetylenes are reviewed and discussed. 

This paper will review the linear and nonlinear optical properties of polydiacetylenes with an emphasis on our work with the nBCMU polymers. The following section will discuss material... 

The aspects of nonlinear optics as applied to polydiacetylenes which will be discussed in this section include... 

We first discuss the materials research which includes monomer synthesis, growth of monomer crystalline structures and polymerization in the solid state, yielding the requisite polymer structures. Next, the nonlinear optical experimental research is discussed which includes a novel experimental technique to measure x (w). Linear and nonlinear optical data obtained for the polydiacetylene films is subsequently presented. Detailed theoretical analysis relating the data to x (< >) and subsequently to its molecular basis will be discussed in a later publication. 

For the elucidation of the optical and nonlinear optical properties of the polydiacetylene layers, we have employed a wave-... 

Linear and nonlinear optical properties of a class of polydiacetylenes that can be grown as large area and controlled thickness thin films have been investigated. This involved an integrated research effort including monomer synthesis, thin film growth and new measurement techniques. 

Nakanishi H, Katagi H (1998) Microcrystals of polydiacetylene derivatives and their linear and nonlinear optical properties. Supramol Sci 5 289-295... 

Polydiacetylenes are obtained as single crystals by topochemical solid-state polymerization of the monomer single crystal. These compounds have received considerable attention because of their one-dimensionally -conjugated structure. Their unique --electron structures, and therefore superior third-order nonlinear optical properties, have been extensively investigated. 

Huggins KE, Son S, Stupp SI. Two-dimensional suptamolecular assemblies of a polydiacetylene. 1. Synthesis, structure, and third-order nonlinear optical properties. Macromolecules 1997 30 5305-5312. 

Conjugated polymers, in the undoped state, present remarkable nonlinear optical properties23. The material which has been most thoroughly investigated ever since 197624 is polydiacetylene para-toluene sulfonate (PTS). The polydiacetylene backbone consists of a... 

The area of molecular nonlinear optics has been rejuvenated by efforts to investigate three-dimensional multipolar systems, functionalized polymers as optoelectronic materials, near infrared optical parametric oscillators and related aspects.71 There have been some advances in chromophore design for second-order nonlinear optical materials 72 these include onedimensional CT molecules, octopolar compounds and organometallics. Some of the polydiacetylenes and poly(/>-phenylenevinylene)s appear to possess the required properties for use as third-order nonlinear optical materials for photonic switching.73... 

Conjugated polymers satisfy these requirements and have thus emerged as the most widely studied materials for their susceptability. Some of the examples of conjugated polymers, that have been studied for their third order NLO properties, are polydiacetylenes, poly-p-phenylenevinylenes and polythiophenes. However, CVD has only been used in the case of poly-p-phenylenevinylenes (PPV) [section 3.4], although values have not been reported. An excellent review of third order nonlinear optical properties of PPV in general, can be found in literature. Recently, McElvain et al. ° reported the values of CVD polyazomethines to be... 

Studies of nonlinear optical phenomena in conjugated polymers date back to the earliest studies of the polydiacetylenes [219], The large oscillator strength associated with the p-p transition gives rise to a relatively large linear electronic polarizibility. The early work speculated that because of the implied delocalization of charge in the excited state, conjugated polymers would offer opportunities as NLO materials. 

Nonlinear Optical and Excited-State Processes in Polydiacetylenes... 

Camacho, M.A., Kar, A.K., Lindsell, W.E.. Murray, C., Preston, P.N., Wherrett, B.S. Synthesis and nonlinear optical properties of functionalized polydiacetylenes and their complexes with transition metals. J. Mater. Chem. 9, 1251-1256 (1999)... 

This reaction, called a four-center photopolymerization, is a typical example of topochemical reactions used to prepare polymer crystals.5 The changes in higher-order structure during the reaction are shown in Table 2.5 . Various polydiacetylene crystals have also been prepared by solid-state photopolymerization of diacetylene monomer crystals, such as 1,6-dicarbazoyl-2,4-hexadiene. These syntheses have attracted considerable interest, since they can lead to organic materials of high conductivity or of nonlinear optical properties. 

Sinclair and coworkersmeasured the third-order nonlinear optical susceptibility of rm 5 -polyacetylene. The measured susceptibility was 5 x 10 esu, which is comparable to the magnitude of the large nonlinear susceptibilities measured in the polydiacetylenes. 

---