Digital twin embodied interactions design: Synchronized and aligned physical sensation in location-based social VR

Digital twin technologies have become increasingly relevant in virtual reality, offering precise 1:1 mapping between physical environments and their virtual counterparts. While previous work has focused on object interaction through passive haptics, little attention has been given to how such environments can support social and embodied interactions that feel natural and expressive. In this work, we extend the digital twin paradigm by integrating full-body avatars, hand tracking, and voice-driven facial animation into a location-based VR environment. To explore the interactive potential of this dual-realm environment, we propose three categories of cross-realm embodied interaction: (1) Tangible interaction, exemplified by spatially aligned object manipulation; (2) Social gesture, supported through expressive hand and body movement; and (3) Social touch, including co-located tactile actions such as handshakes and hugs. We developed a prototype system showing all three embodied interactions, supported by passive haptics, precise spatial alignment, and real-time multiplayer synchronization. We also introduced a low-cost, Wi-Fi-based motion tracking prototype to enhance interaction with movable physical elements. We evaluate the system through expert interviews, identifying key themes related to spatial trust, tactile realism, and interpersonal presence. Our findings suggested that precise alignment and embodied social cues significantly enhance immersion and social connectedness. This work contributes towards a replicable framework for designing socially immersive digital twin experiences and opens new directions for location-based VR in collaborative and educational contexts

Experimental Determination of Effective Minority Carrier Lifetime in HgCdTe Photovoltaic Detectors Using Optical and Electrical Methods

This paper presents experiment measurements of minority carrier lifetime using three different methods including modified open-circuit voltage decay (PIOCVD) method, small parallel resistance (SPR) method, and pulse recovery technique (PRT) on pn junction photodiode of the HgCdTe photodetector array. The measurements are done at the temperature of operation near 77 K. A saturation constant background light and a small resistance paralleled with the photodiode are used to minimize the influence of the effect of junction capacitance and resistance on the minority carrier lifetime extraction in the PIOCVD and SPR measurements, respectively. The minority carrier lifetime obtained using the two methods is distributed from 18 to 407 ns and from 0.7 to 110 ns for the different Cd compositions. The minority carrier lifetime extracted from the traditional PRT measurement is found in the range of 4 to 20 ns for x=0.231–0.4186. From the results, it can be concluded that the minority carrier lifetime becomes longer with the increase of Cd composition and the pixels dimensional area

Ultralow noise DFB fiber laser with self-feedback mechanics utilizing the inherent photothermal effect

Single frequency laser sources with low frequency noise are now at the heart of precision high-end science, from the most precise optical atomic clocks to gravitational-wave detection, thanks to the rapid development of laser frequency stabilization techniques based on optical or electrical feedback from an external reference cavity. Despite the tremendous progress, these laser systems are relatively high in terms of complexity and cost, essentially suitable for the laboratory environment. Nevertheless, more and more commercial applications also demand laser sources with low noise to upgrade their performance, such as fiber optic sensing and LiDAR, which require reduced complexity and good robustness to environmental perturbations. Here, we describe an ultralow noise DFB fiber laser with self-feedback mechanics that utilizes the inherent photothermal effect through the regulation of the thermal expansion coefficient of laser cavity. Over 20 dB of frequency noise reduction below several tens of kilohertz Fourier frequency is achieved, limited by the fundamental thermal noise, which is, to date, one of the best results for a free-running DFB fiber laser. The outcome of this work offers promising prospects for versatile applications due to its ultralow frequency noise, simplicity, low cost, and environmental robustness.</jats:p