title: Lasing from dye-doped icosahedral quasicrystals in dichromate gelatin emulsions.
abstract: Lasing requires an active gain medium and a feedback mechanism. In conventional lasers the feedback is provided externally, e.g. by mirrors. An alternate approach is through Bloch waves in photonic crystals composed of periodic dielectric materials in which propagation of light in certain frequency ranges, known as photonic bandgaps, is forbidden. Compared to periodic crystals, quasicrystals have higher symmetry and are more favorable for the formation of photonic bandgaps. Hence quasicrystals are more efficient in providing the feedback mechanism for lasing. Here we report observation of lasing at visible wavelengths from dye-doped three-dimensional icosahedral quasicrystals fabricated in dichromate gelatin emulsions using a novel seven-beam optical interference holographic method. Multi-directional lasing exhibiting the icosahedral symmetry was observed. The lasing modes and pattern were explained by using the lasing condition expressed in the reciprocal lattice space of the icosahedral quasicrystal.
authors.affiliation: Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Mang Hin
authors.initials: MH
authors.lastname: Kok
authors.forename: Weixin
authors.initials: W
authors.lastname: Lu
authors.forename: Wing Yim
authors.initials: WY
authors.lastname: Tam
authors.forename: George K L
authors.initials: GK
authors.lastname: Wong
mesh_terms: D004396:Coloring Agents / Q000737:chemistry / Q000528:radiation effects; D017076:Computer-Aided Design; D003460:Crystallization / Q000379:methods*; D004655:Emulsions / Q000737:chemistry / Q000528:radiation effects; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005780:Gelatin / Q000737:chemistry / Q000528:radiation effects; D007834:Lasers; D008029:Lighting / Q000295:instrumentation*; D011192:Potassium Dichromate / Q000737:chemistry* / Q000528:radiation effects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D004396:Coloring Agents; D004655:Emulsions; D005780:Gelatin; D011192:Potassium Dichromate