D. Y. Chu

Double‐disk structure for output coupling in microdisk lasers

We report our experiment on the use of a double‐disk structure to couple light output from a microdisk laser which allows us to maintain a high Q value of the microdisk resonator. The small photon leakage rate from the lower lasing disk to the top waveguiding disk can be carefully controlled by choosing the distance between the two disks. Various structures can be fabricated on the top disk to couple the light out. In this letter, a simple opening in the top disk is used for output coupling.

Nanofabrication of 1-D photonic bandgap structures along a photonic wire

A strongly-guided one-dimensional (1-D) waveguide called a photonic wire has high spontaneous emission coupling efficiency, enabling one to realize low-threshold lasers. Combined with the use of 1-D photonic bandgap structures consisting of arrays of holes etched within the photonic wire, novel microcavity lasers can be realized. We report the nanofabrication of a photonic bandgap structure for 1.5 /spl mu/m wavelength along a InGaAsP photonic wire, and discuss numerical simulations for its electrodynamics.

Directional light output from photonic-wire microcavity semiconductor lasers

We have obtained directional light output from a recently realized InGaAsP photonic-wire microcavity ring lasers. The output was achieved by fabricating a 0.45-/spl mu/m-wide U-shape waveguide next to a 10-/spl mu/m diameter microcavity ring laser. The laser has a threshold pump power of around 124 /spl mu/W when optically pumped at 514 nm. It is comparable to the former structure without output coupling. The output coupling efficiency can be controlled carefully by choosing the spacing between the laser cavity and the waveguide.

1.5- mu m InGaAs/InAlGaAs quantum-well microdisk lasers

Microdisk lasers with three InGaAs/InAlGaAs quantum wells were demonstrated for the first time. The selective etching method used to fabricate the laser structure is discussed. Lasers 20 mu m in diameter lased with single mode at 1.5- mu m wavelength when optically pumped by a pulsed argon-ion laser at 80 K.<<ETX>>

Observation of enhanced photoluminescence in erbium‐doped semiconductor microdisk resonator

We report experimental results from an erbium‐doped gallium phosphide microdisk resonator pumped by a Ti‐sapphire laser at 980 nm. Fabrication and characterization of the microdisk resonator are discussed. Enhanced Er+3 intra‐4f‐shell photoluminescence was observed in the microdisk resonator due to microcavity effect and compared to a thin film sample. At low pumping power intensity, the photoluminescence from erbium‐doped gallium phosphide microdisks is an order stronger than that from a thin film sample.

Broadband Bragg filter in microfabricated AlGaAs waveguides

We report on the fabrication and characterization of broadband Bragg filters in microfabricated AlGaAs waveguides. Electron‐beam lithography and chemically assisted ion‐beam etching were used to fabricate first‐order gratings with 250 nm period. Bragg filters with rejection bandwidth ∼15 nm and centered at ∼1.6 μm are demonstrated.

All-optical switching with low-peak power in microfabricated AlGaAs waveguides

We report all-optical switching with low-peak power in a microfabricated AlGaAs waveguide operating at 1.6 /spl mu/m. We show that by using a 1-/spl mu/m long microfabricated strongly-guided waveguide with 0.8 /spl mu/m by 0.9 /spl mu/m mode cross-sectional area, switching is achieved with an average power of 1.2 mW for 82-MHz mode-locked 430 fs pulses. The estimated peak pump power and pulse energy inside the microfabricated waveguide were /spl sim/30 W and /spl sim/14.6 pJ, respectively, which is 5-10 times lower than the values needed with conventional waveguides. In terms of a practicality index defined via switching power times waveguide length, this waveguide has around the best value.<<ETX>>

Novel pulse-delayed scheme for degenerate optical parametric amplification in χ (3) waveguides

We describe a novel pulse-delayed scheme to realize degenerate optical parametric amplification in chi((3)) planar waveguides. The scheme utilizes two identical birefringent plates placed before and after a chi((3)) planar waveguide to implement a single-arm, pulse-multiplexed nonlinear Mach-Zehnder interferometer. Using this scheme, we demonstrate ultrafast degenerate optical parametric amplification in AlGaAs waveguides.

Enhanced Photoluminescence from Erbium-Doped Gap Microdisk Resonator

The fabrication and optical properties of an erbium-doped gallium phosphide microdisk resonator pumped by a Ti-sapphire laser at 980 nm were investigated. Enhanced Er 3+ intra-4f-shell photoluminescence was observed in the microdisk resonator compared to a thin film, and is attributed to a microcavity effect. At low pumping power intensity, the photoluminescence from erbium-doped gallium phosphide microdisks is an order of magnitude more intense than that from a thin film sample.