Electro-optic Characteristics Of Organic Films Doped With DR1 And Its Applications In Electro-optic Probing

Electro-optic probing is an effective detecting method for internal fault of circuit. Using the electro-optic effect of electro-optic materials to convert the electric fields signal on the wire of IC to the laser intensity modulation, then the status of the work of the circuit could be determined. It was harmless on circuit so became a very hot research direction for recent scholars.The properties of probe materials are very important for electro-optic probing technology. The large dielectric constant, the low electro-optic coefficient and the complex process of preparation of inorganic crystals are not fit to be the probe, so the organic materials with small dielectric constant,large electro-optic coefficient and easy preparation have become a new type of electro-optic probe. The purpose of this thesis is to develop DR1 organic polymer-based electro-optical films used as the probe in electro-optic probing. A comprehensive study of the nature of the electro-optic materials has been done in this thesis, and the most important works are focused on the following areas:In this thesis, an electro-optic coefficients measurement formula includes the piezoelectric effect and elastic-optic effect has been concluded at first time. The most popular simple reflection formulas reported before have been amended and improved by 30%. Our calculation indicates that the refractive index of glass couldn't be ignored, otherwise the measurement results will not correct. According to the physical principles of inverse piezoelectric effect, we build the Mach-Zehnder interferometry measurement system to determine the piezoelectric coefficient of polymer, and using two kinds of PZT piezoelectric ceramics for experimental calibration. The measurement results indicate that the system can test the very small piezoelectric coefficient of about 0.04 pm/V. The piezoelectric coefficient in poled DR1/SiO₂ film is less than 0.04 pm/V, so the affect of inverse piezoelectric effect on electro-optic effect is less than 0.2 percent for the DR1/SiO₂ film which always has electro-optical coefficient of 20 pm/V.We developed a corona poling system which has two tungsten wires as the poling electrodes, gave a comprehensive introduction about this system. An instant poling theory has been presented which is very different from the traditional corona poling theories. And at the first time we predicted the electro-optic coefficient of polymer can be the function of intensity and frequency of modulation electric field in view of their physics principle. We have done a lot of experiments to prove the transient effects of in DR1/SiO₂ and DR1/DMF electro-optic films.We do a comprehensive characterization for poling DR1/SiO₂ films, solve the problem of film cracks, prove that the stir temperature of starting solution will be very important factor for the cracks and the varies of electro-optic coefficients. The relationship between the spectral absorption and the electro-optic coefficients of poled DR1/SiO₂ films have also been accounted and experimented. The orientation order parameter of the poled films is large to 0.66, which is far greater than the general polymer orientation order parameters (0.2-0.4). This large orientation order parameter makes the electro-optic coefficient of DR1/SiO₂ poled film up to 37 pm/V. Creative use of the grading method of the orientation order parameters to amend the relarionship between the electro-optic coefficientγ33 andγ13, to increase the accuracy of the measurement of electro-optic coefficient. Use the electrostatic interactions between the chromophore dipoles to explain the impact of the DR1 number density on the electro-optic coefficient. The experiment proved that the optimal number density of DR1 is in the order of 1021 cm-3, and the number density of DR1 is 1.1×1021 cm-3 at which the DR1/SiO₂ films have the largest electro-optic coefficient. Because of the instant poling of DR1, the electro-optic coefficients of DR1/SiO₂ films will depend on the intensity and frequency of modulation electric field. The electro-optical signal non-linear depending on the modulation signal hase been proved. For the first time we observed the surface melting phenomenon of the Al film in the unpoled DR1/SiO₂ film caused by the instant poling effect.Use the finite difference method and computer program to simulate the electric field distribution near the surface of Au electrode. And prove the application of DR1/SiO₂ film as an electric field sensor in the electro-optical probing. But its application must take into account the frequency of the electric field.According to the principle of instant poling, we invent a new technology of electro-optic probing by using the liquid DR1/DMF film as the probe, and realized the probing of the electric signal on Au electrode. The comprehensive study of electro-optic characteristics of DR1/DMF hase been done. For the first time we measured the changes of absorption spectrum under 1000 nm of DMF when applied the poling electric field 100 V/cm, and, with the electric field strength increases, the absorption became more strongly. The comprehensive analysis for absorption characteristics and a lot of experiments proved that the DR1 in DMF have very high poling efficiency and very short response time. Under the 360 V/cm of electric field strength and for 90 seconds, the orientation order parameters reached to 0.68, but under higher electric field intensity, the orientation order parameters began to saturation. compared with the poled DR1/SiO₂ film, the DR1/DMF have greater poling efficient and electro-optic coefficient, at 1k Hz,γ33 reached to 95 pm / V, and at 100 Hz,γ33 increased to 250 pm / V, but the electro-optic coefficient of DR1/SiO₂ just is only 3-10 pm/V with the same number deasity of DR1. Experiments indicated that the optimal number density of DR1 is in the order of 10¹⁹ cm^-3 in DMF. The hindering effect of DMF on the orientation of DR1 is small, so small number density of DR1 will be able to achieve great Electro-optic coefficient. On the other hand, the resisitance of DMF to electrostatic interactions is weaker than the SiO₂, so the doped level in DMF is lower than that in SiO₂. Based on the relationship among the coefficients,frequency and the number density of DR1, we map out the three-dimensional mapγ33-f-N of DR1/DMF to facilitate the promising special applications of such films in electro-optic probing.