Mehmet Bütün | Searcharxiv

arXiv2026

Tailoring complex coupling for efficient synchronization of semiconductor lasers

A grand challenge for laser synchronization is the intrinsic frequency disorder. We build an experimental platform for programming the complex coupling coefficients of semiconductor lasers to promote frequency and phase locking. The coupling amplitude between every pair of lasers in an array is tuned to scale with their frequency difference. Coupling phases are scanned to meet the phase matching conditions for constructive interference of coupled fields. The minimum coupling budget for global synchronization is significantly reduced, as shown experimentally for three vertical-cavity surface-emitting lasers with intrinsic frequency detuning. The customized coupling offers an efficient approach to stable synchronization of semiconductor laser arrays for coherent beam combining.

physics.optics↗

arXiv2025

Subwavelength Phase Engineering Deep Inside Silicon

Recent advances in three-dimensional laser writing have enabled direct nanostructuring deep within silicon, unlocking a volumetric design space previously inaccessible to surface-bound nanophotonic devices. Here, we introduce subwavelength phase engineering inside crystalline silicon, offering a novel strategy for integrated photonics. We design and numerically demonstrate a volumetric metaoptic monolithically embedded within the bulk, achieving full 2$π$ phase control at telecommunication wavelengths, with simulated transmission efficiencies reaching 90 %. The architecture is guided by a semi-analytical Fabry-Perot model and validated through full-wave simulations. Arrays of 250-nm-wide metaatoms spaced at 300-410 nm pitch yield a focusing efficiency of 70 %. With the wafer surface left pristine, this platform can potentially enable co-integration with electronics, MEMS/NEMS, and conventional metasurfaces. Moreover, the method is directly transferable to other transparent dielectrics compatible with ultrafast laser writing. These results establish a CMOS-compatible blueprint for three-dimensional nanophotonics and multi-level integration within the wafer.

physics.optics↗