Nanophotonic resonator

A nanophotonic resonator or nanocavity is an optical cavity which is on the order of tens to hundreds of nanometers in size. Optical cavities are a major component of all lasers, they are responsible for providing amplification of a light source via positive feedback, a process known as amplified spontaneous emission or ASE. Nanophotonic resonators offer inherently higher light energy confinement than ordinary cavities, which means stronger light-material interactions, and therefore lower lasing threshold provided the quality factor of the resonator is high.[1] Nanophotonic resonators can be made with photonic crystals, silicon, diamond, or metals such as gold.

For a laser in a nanocavity, spontaneous emission (SE) from the gain medium is enhanced by the Purcell effect,[2][3] equal to the quality factor or -factor of the cavity divided by the effective mode field volume, . Therefore, reducing the volume of an optical cavity can dramatically increase this factor, which can have the effect of decreasing the input power threshold for lasing.[4][5] This also means that the response time of spontaneous emission from a gain medium in a nanocavity also decreases, the result being that the laser may reach lasing steady state picoseconds after it starts being pumped. A laser formed in a nanocavity therefore may be modulated via its pump source at very high speeds. Spontaneous emission rate increases of over 70 times modern semiconductor laser devices have been demonstrated, with theoretical laser modulation speeds exceeding 100 GHz, an order of magnitude higher than modern semiconductor lasers, and higher than most digital oscilloscopes.[2] Nanophotonic resonators have also been applied to create nanoscale filters [6][7] and photonic chips [6]

  1. ^ Akahane, Yoshihiro; Asano, Takashi; Song, Bong-Shik; Noda, Susumu (2003). "High-Q photonic nanocavity in a two-dimensional photonic crystal". Nature. 425 (6961). Springer Science and Business Media LLC: 944–947. Bibcode:2003Natur.425..944A. doi:10.1038/nature02063. ISSN 0028-0836. PMID 14586465. S2CID 4415688.
  2. ^ a b Altug, Hatice; Englund, Dirk; Vučković, Jelena (2006). "Ultrafast photonic crystal nanocavity laser". Nature Physics. 2 (7). Springer Science and Business Media LLC: 484–488. Bibcode:2006NatPh...2..484A. CiteSeerX 10.1.1.162.2125. doi:10.1038/nphys343. ISSN 1745-2473.
  3. ^ Purcell, E. Spontaneous emission probabilities at radio frequencies. Phys. Rev. 69, 681 (1946).
  4. ^ Painter, O. (1999-06-11). "Two-Dimensional Photonic Band-Gap Defect Mode Laser". Science. 284 (5421). American Association for the Advancement of Science (AAAS): 1819–1821. doi:10.1126/science.284.5421.1819. ISSN 0036-8075. PMID 10364550. S2CID 6627734.
  5. ^ Lončar, Marko; Yoshie, Tomoyuki; Scherer, Axel; Gogna, Pawan; Qiu, Yueming (2002-10-07). "Low-threshold photonic crystal laser" (PDF). Applied Physics Letters. 81 (15). AIP Publishing: 2680–2682. Bibcode:2002ApPhL..81.2680L. doi:10.1063/1.1511538. ISSN 0003-6951.
  6. ^ a b Noda, Susumu; Chutinan, Alongkarn; Imada, Masahiro (2000). "Trapping and emission of photons by a single defect in a photonic bandgap structure". Nature. 407 (6804). Springer Science and Business Media LLC: 608–610. Bibcode:2000Natur.407..608N. doi:10.1038/35036532. ISSN 0028-0836. PMID 11034204. S2CID 4380581.
  7. ^ Song, B.-S. (2003-06-06). "Photonic Devices Based on In-Plane Hetero Photonic Crystals". Science. 300 (5625). American Association for the Advancement of Science (AAAS): 1537. doi:10.1126/science.1083066. ISSN 0036-8075. PMID 12791984. S2CID 7647042.