On the Stability of Spatially Distributed Cavity Laser and Boundary of Resonant Beam SLIPT

TL;DR

This work tackles the fundamental limitation of long-range spatially distributed cavity (SDC) lasers for SLIPT, arising from cavity stability and manufacturing tolerances that amplify diffraction losses over distance. It develops a comprehensive ABCD-matrix-based stability framework and two tolerance-analysis methods—a binary-search-based Monte Carlo (BMC) approach and a linear approximation—that quantify the maximum allowable tolerances for stable operation. The authors demonstrate that the stable region contracts rapidly with transmission distance and show that incorporating adjustable elements (e.g., the telescope interval $d_{ m t}$) enables stable operation up to several meters; experiments extend the range to $2.8$ m. The results provide design guidelines and practical strategies for realizing long-range SDC systems suitable for mobile IoT, WPT, and SLIPT applications.

Abstract

Spatially distributed cavity (SDC) lasers are a promising technology for simultaneous light information and power transfer (SLIPT), offering benefits such as increased mobility and intrinsic safety, which are advantageous for various Internet of Things (IoT) devices. \mll However, achieving beam transmission over meter-level long working distances presents significant challenges from cavity stability constraints, manufacturing/assembly tolerances, and diffraction losses\mrr. This paper conducts a theoretical investigation of the fundamental restrictions limiting long-range resonant beam generation. We investigate cavity stability and beam characteristics, and propose a binary-search-based Monte Carlo simulation algorithm as well as a linear approximation algorithm to quantify the maximum acceptable tolerances for stable operation. \mll Numerical results indicate that the stable region contracts sharply as distance increases. For fixed-component systems, an acceptable tolerance of 0.01 mm restricts the achievable transmission distance to less than 2 m. \mrr To address this limitation, we also prove the feasibility of long-range beam formation using precision adjustable elements, paving the way for advanced engineering applications. \mll Experimental results verified this assumption, demonstrating that by tuning the stable region during assembly, the transmission distance could be extended to 2.8 m. \mrr This work provides essential theoretical insights and practical design guidelines for realizing stable, long-range SDC systems.

Figures (15)

• Figure 1: SDC application scenario diagram (a) indoor smart living (b) industrial intelligence.
• Figure 2: Spatially distributed cavity laser for mobility enhanced SLIPT. (Tx: transmitter; Rx: receiver; PV: photovoltaic cells; PD: photodiode)
• Figure 3: System design of the duplex simultaneous light information and power transfer system based on a coupled spatially distributed cavity: (a) fundamental deployment, (b) cavity with internal telescope, (c) common telecentric cat's eye retroreflector, (d) retroreflector with focusing ability. M1, M2: mirrors; L1--L4: lenses; $d1$, $d2$, $f1$--$f4$, $d_w$: intervals between elements; $f1$--$f_4$ are also focal lenses of L1--L4, respectively
• Figure 4: Stability parameter $g$ under different ($d_1,d_{\rm t}$): (a)--(d) shows different working distance $d_{\rm w}$, and (e)--(f) shows different deviation $\delta d_{\rm g}$.
• Figure 5: Stable region width under different working distance $d_{\rm w}$ (solid line: $\mathcal{D}_{d_1}$; dash line: $\mathcal{D}_{d_{\rm t}}$; $d_{\rm g}=f_1+f_3$).