Nonlinear Optical Polymer Film Of Bacteria Rhodopsin Gene Mutation And Applied Research In Holographic Storage

The content of this thesis consist of three parts. First part is the study of the absorption spectra and the photoinduced nonlinearity in a novel Bacteriorhodopsin mutant (BR-D96V/PVA). The holographic application of this BR mutant is discussed in the second part of this thesis. At last, a brand new design of the spectrometer with multiple functions is proposed and developed.First, the absorbance change of a polymeric film containing the BR mutant was induced by laser beam and the pertinent Z-Scan was performed. Optical nonlinearity was found, and accounted for by the optical and thermal effects. The single beam Z-Scan technology was applied to measure the nonlinearity of the BR film. By analyzing the complicated and varied results of the Z-Scan, we observed the regulations related to the wavelength and the intensity of the induced laser. A new physical model was suggested with the assumption that the BR photocycle is a multi-level process, and the experimental results of the nonlinearity by the Z-Scan method were fitted well. The results of simulation show the high nonlinear refraction coefficient and the corresponding to the range of optimal irradiation intensity. The simulations using the model reveal that the photo-induced nonlinear refraction and absorption of BR film are the combinations of both saturation effect and reverse saturation effect of the initial B-state and each intermediate state. Two nonlinear refractions, induced by two overlapped laser beam with different wavelength and formed at the same position of the BR sample, were demonstrated indifferent to each other. This result indicates that multiple refraction conformation could be structured at same area of film with different wavelengths. The index of nonlinear refraction of this sample are-3.7x10-3 cm2/W (633 nm),-7.8x10-2 cm2/W (476 nm), respectively for the intensity within 0.1 W/cm2. The quality factor of the reverse saturable absorption are 6.5 (633 nm) and 4.0 (476 nm), which indicates the existence of a relatively high optical limiter effect in the BR film.Second, we investigated the influence of the parameters in the holographic application with the BR-D96V/PVA film. Base on the experimental investigation, to obtain a better holographic image, several parameters are suggested as follows:the optical density of the BR film should be large enough, the violet laser (405 nm) should be used as the assistant, the intensity of the lasers (476 nm and 633 nm) should be fixed on the region where the violet laser enhances the signal, the ration of the lasers (probe, write and reference) should be around 1:100:100. Therefore, we performed the holographic experiment with suggested parameters. The refraction grating was established in the BR film with the lasers at 476 nm and 633 nm. The multiple diffracted results were obtained. With the enhancement of the laser at 405 nm, we achieved the holograph with the blue and the violet lasers for the first time. In addition, the multiple angle holographs with the blue and the violet lasers were obtained for the first time. With the laser at 405nm, the holographs with the lasers at 476 nm and 633 nm simultaneously at the same area of the sample were obtained for the first time.In the addendum, a novel design of the spectrometer with multiple functions was proposed. The electrical system design was nearly finished and the hardware of the electrical system was assembled. The debugging of the hardware and the development of the software was launched and the primary achievement was acquired.