Fecha de publicación: -- Fuente: PubMed "swarm" Opt Lett. 2026 Oct 15;51(20):5818-5821. doi: 10.1364/OL.614924. Epub 2026 Sep 30.ABSTRACTWe demonstrate a compact, foundry-compatible silicon thermo-optic phase shifter (TOPS) based on a substrate-undercut doped-silicon heater, achieving a π-phase-shift power of P π =0.74 mW at a drive voltage of only V π =0.91 V. Prior low-power phase shifters reach comparable or lower P π only by extending the heated length, enlarging the footprint, and none report CMOS-compatible drive voltages. Here, both the heater and the 2×2 multimode interference (MMI) couplers are optimized using particle swarm optimization (PSO), the former to jointly minimize P π and optical loss at a fixed 100 µm length in a compact 240×73 µm2 footprint. Integrated into a Mach-Zehnder switch, the device shows an insertion loss of 0.90 dB, an extinction ratio of 23 dB, and rise/fall times of 1.38/1.02 ms. To our knowledge, this is the first foundry-fabricated TOPS to combine sub-milliwatt P π , a compact low-latency arm, and a sub-1-V CMOS-compatible V π , offering a scalable route to low-energy programmable silicon photonic meshes.PMID:42900128 | DOI:10.1364/OL.614924