Photopolymers are appealing materials for many optical applications. For most of them, shrinkage plays an important role in the final properties of the display, especially in holographic data storage applications. In this paper, we demonstrate that to quantify correctly the shrinkage, it is mandatory to measure the angle of propagation for both diffracted orders ± 1, so that an accurate value o...

Organic photorefractive polymer composites can be made to exhibit near 100% diffraction efficiency and fast writing times, though large external slants are needed to project the applied field onto the grating vector. We show here that the use of interdigitated electrodes on a single plane provides similar performance to these standard devices and geometries but without a external slant angle. T...

We have developed a self-aligned external cavity laser with a non-dispersive volume holographic grating (VHG) as the output coupler. The resulting external cavity is tunable by rotating the VHG. We have demonstrated tunable single mode longitudinal operation at 405 nm and 785 nm wavelength. The passive alignment of the novel tunable laser is the main driver for achieving low cost manufacturing....

The proposed thesis is to build a power build-up cavity pumped by a laser diode. In Raman spectroscopy there is a need for high power laser diode sources to be used in Raman gas monitoring applications. A high power laser source will allow the development of compact and low cost systems for use in any gas monitoring application where detection into the ppb is necessary. Gas detection can be acc...

Wavelength-locking by a volume holographic grating (VHG) is reported for a diode laser bar with 49 single mode emitters, fitted with a dual-axis collimation phase-plate for smile elimination and excellent beam pointing correction. The much-improved VHG feedback with the ultra-collimated array beam gives 100% wavelength locking at 975 nm over a 17°C temperature range and external cavity lengths ...

In this paper, we propose a method for efficient gonio-imaging of optically variable devices (OVDs), which are applied as a counterfeit deterrence for valuable documents. A compound-eye image-capturing system composed by a microlens array, a signal separator, and an image sensor was used to capture directionally distributed light from OVDs after being collimated by a convex lens. Multiple image...

We demonstrate holographic recording in a new photopolymer system. The recording material is created by copolymerization of an optically inert monomer, methyl methacrylate, and a second monomer that is optically sensitive. On exposure of the recording material to light, a portion of the optically sensitive component detaches from the polymer matrix and causes hologram amplification through diff...

In this paper, we show that photosensitive azo-dye doped Blue-phase liquid crystals (BPLC) formed by natural molecular self-assembly are capable of high diffraction efficiency holographic recording with memory that can be prolonged from few seconds to several minutes by uniform illumination with the reference beam. Operating in the Bragg regime, we have observed 50 times improvement in the grat...

During polarization holographic recording in azopolymer thin films, usually together with the volume anisotropic grating, a surface relief grating (SRG) is also formed. By using two consecutive exposures, it possible to obtain two-dimensional (2D) grating. To best of our knowledge, properties such gratings have not been studied yet. determine influence on selectivity 2D gratings, we propose met...

The experimental comparison between two concave holographic gratings with identical recording geometries and different exposure conditions demonstrates some possibilities for the optimization of the integral diffraction efficiency.