Photonic-well Microcavity light emitting devices
AssigneeNorthwestern University
InventorSeng-Tiong Ho
Life of this patent
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Abstract
A photonic light emitting device comprising a relatively high refractive index photonic-well semiconductor waveguide core in the form of an arcuate shape, linear shape and combinations thereof. The waveguide core is formed into a closed loop cavity for a light-emitting device or laser. The waveguide core is surrounded by relatively low refractive index medium and comprises an active medium having major and minor sides and semiconductor guiding layers proximate the major sides. The active medium and the guiding layers are so dimensioned in a transverse direction relative to the path of light propagation through the core to provide significantly increased spontaneous-emission coupling efficiency, leaading to low lasing threshold and high intrinsic modulation rates.
Claims43
A light emitting device comprising a relatively high refractive index photonic-well semiconductor waveguide core surrounded on opposite sides in a direction transverse to photon propagation direction by relatively low refractive index medium to spatially confine photons strongly in said direction transverse to their propagation direction in the waveguide core, said waveguide core being an annular waveguide core with an inner rim, said rim being rough for R less than 50 lamda/n.sub.core and said waveguide core comprising an optically active excitable medium having a major and minor sides and guiding semiconductor medium proximate said major sides, said active excitable medium and said guiding medium being so dimensioned in said transverse direction relative to the path of light propagation through the waveguide core as to provide significantly increased spontaneous-emission coupling efficiency for photons emitted into an electromagnetic field mode.
Light-emitting device comprising at least one waveguide element providing for spatially channeling a substantial fraction, characterized by Beta(space), of photons emitted from an excited medium into an electromagnetic field mode of interest using a photonic-well waveguide as said waveguide element, and one element for achieving a resonant optical cavity cooperating with said photonic-well waveguide, the electromagnetic field mode of interest being a TE or TM guided mode of said photonic-well waveguide, said photonic-well waveguide comprising a relatively high refractive index waveguide core with refractive index n.sub.core which is surrounded in a direction transverse to photon propagation direction by relatively low refractive index medium with refractive index n.sub.low to spatially confine photons strongly in the transverse direction perpendicular to their propagation direction, said waveguide core in another direction normal to said transverse direction being surrounded by relatively high refractive index material with refractive index n.sub.high, providing a relatively weak photon confinement in the said another direction, said n.sub.core adn n.sub.low having a ratio of larger than 1.3 and said n.sub.core adn n.sub.high having a ratio of larger than 1.001, said waveguide core having a dimension ds in said transverse direction and dw in said another direction, said dimension dw having a normalized value ds.sub.n larger than 0.1 and smaller than 4.0 where ds.sub.n =ds/ds.sub.lambda with ds.sub.lambda =Lambda/n.sup.s.sub.eff, where lambda is the active-layer emission wavelength in free space (vacuum or in the absence of material medium) and n.sup.s.sub.eff is the effective refractive index given by n.sup.s.sub.eff =Sqrt(n.sub.core.sup.2 -n.sub.low.sup.2), and Sqrt denotes square rooting, said dimension dw having a normalized value dw.sub.n larger than 0.1 and smaller than 1.1 for single-mode guiding and for Beta(space) value, where dw.sub.n ==dw/dw.sub.lambda with dw.sub.lambda =lambda/n.sup.w.sub.eff, where n.sup.w.sub.eff is the effective refractive index given by n.sup.w.sub.eff =Sqrt(n.sub.core.sup.2 -n.sub.high.sup.2).
Dependencies are inferred from the claim text.