Latest Bayfol HX® developments: ultrahigh index modulation and NIR recordable holographic films

Bayfol® HX photopolymer films prove themselves as easy-to-process recording materials for volume holographic optical elements (vHOEs) and are available in customized grades at industrial scale. Their full-color (RGB) recording and replay capabilities are two of their major advantages. Moreover, the adjustable diffraction efficiency, tunable angular and spectral selectivity of vHOEs recorded into Bayfol® HX as well as their unmatched optical clarity enables superior invisible “off Bragg” optical functionality. As a film product, the replication of vHOEs in Bayfol® HX can be carried out in a highly cost-efficient and purely photonic roll-to-roll (R2R) process. Utilizing thermoplastic substrates, Bayfol® HX was demonstrated to be compatible to state-of-the-art plastic processing techniques like thermoforming, film insert molding and casting, all enabled using a variety of industry-proven integration technologies for vHOEs. Therefore, Bayfol® HX made its way in applications in the field of augmented reality such as Head-up-Displays (HUD) and Headmounted- Displays (HMD), in free-space combiners, in plastic optical waveguides, and in transparent screens. Also, vHOEs made from Bayfol® HX are utilized in highly sophisticated spectrometers in astronomy as well as in narrow band notch filters for eyeglasses against laser strikes. Based on a well-established toolbox, Bayfol® HX can be adopted for a variety of applications. To further offer access to more applications in sensing and continuously improve the performance in existing applications, we recently extended our chemical toolbox to address both the sensitization beyond RGB into the Near Infrared Region (NIR) and increase the achievable index modulation Δn1 beyond 0.06. In this paper, we will report on our latest developments in these fields.