Ultra‐Compact Beam Switching Nanolasers

The miniaturization and integration of beam control devices is a key focus in the field. Conventional methods alter the refractive index to modulate the eigenmode of optical cavities, but due to weak nonlinearity, large devices are needed for sufficient light modulation. Metasurfaces are currently an important solution for miniaturized devices, but in which the generation and modulation of light waves can only be performed separately. Here, a miniaturized beam switching device is proposed that utilizes phase change material (Sb2Se3) to select between different bound states in the continuum (BICs). This device achieves simultaneous light generation and beam switching (33°) in a compact size of 25 × 25 µm2, with a low threshold of 6.6 kW cm⁻2. It also offers dynamic wavelength tunability up to 296 nm. This method provides efficient control of light by dynamically manipulating topological properties, overcoming the challenges of weak nonlinearity in conventional systems. Additionally, integrating phase change materials with nanolasers enables direct modulation of lasing properties, presenting a new approach for dynamic light control at the nanoscale. The phase change material‐based process is simple, direct, and compatible, offering advantages for on‐chip optoelectronic integration.