Tuneable photonic crystal lasers and a method of fabricating the same
First Claim
1. A waveguide for conducting light comprising:
- a substrate;
a high refractive index waveguiding membrane disposed over the substrate forming an air cavity therebetween, the waveguiding membrane confining the light propagating therein by way of total internal reflection, the waveguiding membrane thickness as measured by the wavelength of light propagating in the waveguiding membrane is less than one wavelength thick;
a photonic bandgap (PBG) crystal being defined in said waveguiding membrane by a periodic array of holes defined through the waveguiding membrane; and
an optical cavity being defined in the photonic bandgap (PBG) crystal by means of a defect in the periodicity of the array of holes in said waveguiding membrane, the optical cavity confining light therein, and having a mode volume on the order of one cubic wavelength or less.
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Abstract
Room temperature lasing from optically pumped single defect in a two-dimensional photonic bandgap crystal is illustrated. The high Q optical microcavities are formed by etching an array of air holes into a half wavelength thick multiquantum well waveguide. Defects in the two-dimensional photonic crystal or used to support highly localized optical modes with volumes ranging from 2 to 3 (λ/2n)3. Lithographic tuning of the air hole radius and the lattice spacing is used to match the cavity wavelength to the quantum well gain peak, as well as to increase cavity Q. The defect lasers were pumped with 10-30 nsec pulse of 0.4-1 percent duty cycle. The threshold pump power was 1500 milliwatts. The confinement of the defect mode energy to a tiny volume and the enhancement of the spontaneous emission rate make the defect cavity an interesting device for low threshold, high spontaneous emission coupling factor lasers, and high modulation rate light emitting diodes. Optic structures formed from photonic crystals also hold promise due to the flexibility of their geometries. Lithographic methods may be employed to alter the photonic crystal geometry so as to tune device characteristics. The integration of densely packed photonic crystal waveguides, prisons, and light sources integrated on a single monolithic chip is made possible. Lithographically defined photonic crystal cavities may also find use in some material systems as an alternative to epitaxially grown mirrors, such as for long wavelengths vertical cavity surface emitting lasers (VCSEL) and GaN based devices.
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Citations
52 Claims
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1. A waveguide for conducting light comprising:
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a substrate;
a high refractive index waveguiding membrane disposed over the substrate forming an air cavity therebetween, the waveguiding membrane confining the light propagating therein by way of total internal reflection, the waveguiding membrane thickness as measured by the wavelength of light propagating in the waveguiding membrane is less than one wavelength thick;
a photonic bandgap (PBG) crystal being defined in said waveguiding membrane by a periodic array of holes defined through the waveguiding membrane; and
an optical cavity being defined in the photonic bandgap (PBG) crystal by means of a defect in the periodicity of the array of holes in said waveguiding membrane, the optical cavity confining light therein, and having a mode volume on the order of one cubic wavelength or less. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
epitaxially grown p- and n-doped contact layers;
a self-aligned electrical pumping aperture between said epitaxially grown p- and n-doped contact layers, wherein selective oxidation through said holes which define said photonic crystal electrically isolate said p- and n-doped regions within said photonic crystal; and
a ring contact to electrically pump said aperture layer.
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28. A method of fabricating a waveguide for propagating light comprising:
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providing a high refractive index waveguiding membrane to confine the light propagating therein by way of total internal reflection, the waveguiding membrane disposed over a substrate forming an air cavity therebetween;
providing said waveguiding membrane with a thickness as measured by the wavelength of light propagated in the waveguiding membrane of less than the wavelength;
providing a photonic bandgap (PBG) crystal in said waveguiding membrane by defining a periodic array of holes through the waveguiding membrane; and
defining a defect in the periodicity of the array of holes to define an optical cavity in the photonic bandgap (PBG) crystal, the optical cavity confining light therein and having a mode volume on the order of one cubic wavelength or less. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
epitaxially growing p- and n-doped contact layers;
defining a self-aligned electrical pumping aperture between said epitaxially grown p- and n-doped contact layers;
selectively oxidizing through said holes which define said photonic crystal to electrically isolate said p and n doped regions within said photonic crystal; and
disposing a ring contact on said contact layers to electrically pump said layer.
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Specification