Waveguide displays based on a volume holographic grating (VHG) have the benefit of expanding the exit pupil. Exit pupil size and exit pupil uniformity are two important indicators of waveguide displays. Most current optimizations for exit pupil uniformity are based on the central viewing angle. However, this does not ensure satisfied exit pupil uniformity for other viewing angles. In this paper, a method based on a genetic algorithm to optimize the exit pupil uniformity under the whole horizontal field of view (HFOV) is proposed. First, the ray-tracing-based mathematical model to analyze the uniformity of the whole HFOV at all wavelengths is established. Based on the mathematical model, the objective function can be defined, which can optimize the refractive index modulation distribution on several regions of the out-coupling VHG. The simulation results show that for a holographic waveguide display with the exit pupil size of 16mm×12mm, the average exit pupil uniformity can reach 86.87% at a diagonal field of view (DFOV) of 30°, a 9.16% improvement over the previous method. The genetic-algorithm-based method proposed in the paper can effectively improve the exit pupil uniformity.

The two phosphate glasses with composition 17K2O−17Gd2O3−65P2O5−01Er2O3 and 17KF−17Gd2O3−65P2O5−01Er2O3 composition were synthesized by conventional-melt quenching techniques to study comparatively the spectroscopic, Judd–Ofelt (JO), radiative properties and NIR-luminescent properties. The Urbach energy of K2O−Er and KF-Er samples was 0.3547 and 0.4799 eV. The observed trend is Ω2>Ω4>Ω6 and Ω2>Ω6>Ω4 for JO-intensity-parameters for K2O−Er and KF-Er glasses. Moreover, K2O−Er has higher Ω4 and Ω6 values, thus having more rigidity and viscosity than KF-Er. The measured values of full-width-half-maximum (FWHM) for K2O−Er and KF-Er glasses 54.60 and 58.27, respectively. The measured values of FWHM for K2O−Er and KF-Er glasses were 54.60 and 58.27, respectively. The A R values are 417.61 and 3038 for K2O−Er and KF-Er glasses, respectively. The radiative lifetime (τ R ) for K2O−Er and KF-Er glasses is 2.39 ms and 3.18 ms, respectively. Utilizing McCumber theory the G(λ,β) is positive and population-inversion is more than 0.4 for both glasses. Both samples have flat gain-bandwidth in the range of 1505–1585 nm, which covers the S-, C-, and L-bands of the low-loss optical communication-window. It is evident from all these results that the prepared glass samples have the potential for a low-threshold and high gain NIR laser and optical-fiber amplifier.

Scannerless laser three-dimensional (3D) imaging relies on large-scale detector arrays to achieve high-resolution imaging and is one of the main technologies in light detection and ranging (LIDAR). However, the high production cost and complex manufacturing process is limiting the imaging resolution. In this paper, we demonstrate a subpixel 3D imaging method based on two-dimensional (2D) encoding and decoding. First, an LED array projects 2D spatio-temporal coded light beams onto the target space. Accordingly, an optical multiplexer separates and reconstructs the backscattered signals into a small-scale avalanche photodiode (APD) array. We designed a prototype with a 16×16 optical encoding and a 2×2 APD array. The scannerless imaging reconstructs 256 pixels per frame within the distance range of 39–68 cm.

In this study, we introduce what we believe is an innovative design for a plasmonic perfect absorber (PPA) that is based on half-cut disk resonator metamaterials. This design exhibits remarkable stability and versatility, demonstrating effective functionality across a wide range of incident angles for both transverse electric (TE) and transverse magnetic (TM) polarization. The distinct operational characteristics of the PPA are highlighted by the presence of two corresponding absorption peaks at wavelengths of 870 and 1599 nm, where it achieves outstanding maximum absorption rates of 98.99% and 97.5%, respectively. The design’s ultra-narrow resonance peaks are indicative of its high-quality factors, which are vital for enhancing sensitivity in plasmonic sensory applications. This characteristic renders our PPA an exceptional candidate for refractive index (RI) sensing, where precision is critical. The dual-band perfect absorber (PA)-based sensor demonstrates significant RI sensitivity, with values approximately equal to 365 nm/RIU at the first absorption peak and 733 nm/RIU at the second. Our findings elucidate the exceptional potential inherent in this novel dual-band perfect absorber design. The versatility and efficiency across varied applications not only contribute to the existing body of knowledge but also pave the way for future advancements in plasmonic sensor technologies and metamaterial research.