Hologram recording in polyvinyl alcohol/acrylamide photopolymers by means of pulsed laser exposure

Abstract

The variation in transmittance produced when a photopolymer is irradiated with a pulsed laser is analyzed and experimental results obtained when diffraction gratings are stored using pulsed exposure are presented. In either case, the influence of the energy of the irradiation pulse, the number of pulses, and the pulse repetition rate were studied. The photopolymer used was an acrylamide͞polyvinyl alcohol dry film with a yellow eosin-thiethanol-amine mixture as a photoinitiator system. The recording of the gratings was performed by use of a holographic copying process. The samples were exposed and holograms recorded with a collimated beam from a frequency-doubled Nd:YAG ͑532 nm͒ Q-switched laser. Our initial results show that it is possible to obtain diffraction gratings with a diffraction efficiency of 60% and a refractive index modulation up to 2.8 ϫ 10 Ϫ3. The energetic sensitivities achieved are close to those obtained with the same material and continuous irradiation without a preprocessing of the gratings.

Temporal evolution of the angular response of a holographic diffraction grating in PVA/acrylamide photopolymer

“…The angular response of the same grating in the recorded direction is not possible due to the behavior in real time exhibited by photopolymerizable materials based on PVA/acrylamide. In such materials when exposure is discontinued in order to measure the angular response and the material is then exposed again to the laser, it does not react as it did before [9]. In other words, the behaviour of the photopolymer in the case of two nonconsecutive exposures is different to its behaviour in the case of one continuous exposure which is the sum of the former two.…”

Characterization and estimation of refractive index profile of laser-written photopolymer optical waveguides

“…− 3 was reported in [10], yet the peak modulation is estimated to be 1.3 × 10 − 3 using a 0.5 mW CW laser in this study.…”

“…Sensitivity of the procedure for peak index modulation may be obtained from this figure, as depicted for 5 × 10 − 5 peak index change; peak intensity of the first-order diffraction peak reveals this information. Correspondingly, for holographic grating methods, the first-order diffraction peak is generally considered for characterization as in [10]. The final plot for the multiple-pass waveguide structure is shown with the reconstruction curve in Fig.…”

A fiber-integrated optical component fabricated via photopolymerization: Mode-selective grating coupler

“…Photopolymerization is a popular research area and a practical tool for the fabrication of optical components; the focus is particularly common in creation of holographic memory systems [1,2]. The main reasons for the popularity are the low-cost material, simple handling and easy production.…”