External Cavity Diode Lasers for Atom Gravimetry: A Review of Structures, Performance, and Miniaturization Strategies

External cavity diode lasers (ECDLs), with their narrow linewidth, high frequency stability, and tunable wavelengths, are key light sources in atom gravimeters (AGs). As these instruments evolve toward portable, vehicular, and space‐based deployments, their laser systems face increasing demands on integration, robustness, and power efficiency. This review examines four representative ECDL configurations—Littrow, Littman, volume holographic grating, and filter‐based types—analyzing their structural characteristics, performance trade‐offs, and suitability for miniaturization. The comparative assessment highlights inherent compromises among output power, tuning range, frequency stability, and system‐level integration. Miniaturization emerges as a pivotal enabler for AG engineering applications. Three primary approaches have gained traction: microelectromechanical system (MEMS) tuning offers a compact, low‐power solution ideal for portable quantum systems; waveguide feedback structures provide excellent spectral stability and fiber integration; and III–V/Si heterogeneous integration enables chip‐scale, high‐gain lasers for next‐generation precision measurement platforms.