Terahertz Room-Temperature Photonic Crystal Nanocavity Laser

We describe an efficient surface-passivated photonic crystal nanocavity laser, demonstrating room-temperature operation with 3-ps total pulse duration (detector response limited) and low-temperature operation with ultra-low-threshold near 9uW.Comment: 6 pages, 3 figure

Tailoring Chirp in Spin-Lasers

The usefulness of semiconductor lasers is often limited by the undesired frequency modulation, or chirp, a direct consequence of the intensity modulation and carrier dependence of the refractive index in the gain medium. In spin-lasers, realized by injecting, optically or electrically, spin-polarized carriers, we elucidate paths to tailoring chirp. We provide a generalized expression for chirp in spin-lasers and introduce modulation schemes that could simultaneously eliminate chirp and enhance the bandwidth, as compared to the conventional (spin-unpolarized) lasers.Comment: 4 pages, 3 figure

Photoluminescence measurements of quantum-dot-containing semiconductor microdisk resonators using optical fiber taper waveguides

Fiber taper waveguides are used to improve the efficiency of room temperature photoluminescence measurements of AlGaAs microdisk resonant cavities with embedded self-assembled InAs quantum dots. As a near-field collection optic, the fiber taper improves the collection efficiency from microdisk lasers by a factor of ~ 15-100 times in comparison to conventional normal incidence free-space collection techniques. In addition, the fiber taper can serve as a efficient means for pumping these devices, and initial measurements employing fiber pumping and collection are presented. Implications of this work towards chip-based cavity quantum electrodynamics experiments are discussed.Comment: 10 pages, 7 figure

Scaling of losses with size and wavelength in nanoplasmonics and metamaterials

We show that, for the resonant metal-dielectric structures with sub-wavelength confinement of light in all three dimensions, the loss cannot be reduced significantly below the loss of the metal itself unless one operates in the far IR and THz regions of the spectrum or below. Such high losses cannot be compensated by introducing gain due to Purcell-induced shortening of recombination times. The only way low loss optical metamaterials can be engineered is with as yet unknown low loss materials with negative permittivity.Comment: Submitted to AP

Silicon-photonics light source realized by III-V/Si grating-mirror laser

A III-V/Si vertical-cavity in-plane-emitting laser structure is suggested and numerically investigated. This hybrid laser consists of a distributed Bragg reflector, a III-V active region, and a high-index-contrast grating (HCG) connected to an in-plane output waveguide. The HCG and the output waveguide are made in the Si layer of a silicon-on-insulator wafer by using Si-electronics-compatible processing. The HCG works as a highly-reflective mirror for vertical resonance and at the same time routes light to the in-plane output waveguide. Numerical simulations show superior performance compared to existing silicon light sources

Lasing from a circular Bragg nanocavity with an ultra-small modal volume

We demonstrate single-mode lasing at telecommunication wavelengths from a circular nanocavity employing a radial Bragg reflector. Ultra-small modal volume and Sub milliwatt pump threshold level are observed for lasers with InGaAsP quantum well active membrane. The electromagnetic field is shown to be tightly confined within the 300nm central pillar of the cavity. The quality factors of the resonator modal fields are estimated to be on the order of a few thousands.Comment: 3 pages, 4 figures Submitted to AP

Optical loss and lasing characteristics of high-quality-factor AlGaAs microdisk resonators with embedded quantum dots

Optical characterization of AlGaAs microdisk resonant cavities with a quantum dot active region is presented. Direct passive measurement of the optical loss within AlGaAs microdisk resonant structures embedded with InAs/InGaAs dots-in-a-well (DWELL) is performed using an optical-fiber-based probing technique at a wavelength (lambda~1400 nm) that is red-detuned from the dot emission wavelength (lambda~1200 nm). Measurements in the 1400 nm wavelength band on microdisks of diameter D = 4.5 microns show that these structures support modes with cold-cavity quality factors as high as 360,000. DWELL-containing microdisks are then studied through optical pumping at room temperature. Pulsed lasing at lambda ~ 1200 nm is seen for cavities containing a single layer of InAs dots, with threshold values of ~ 17 microWatts, approaching the estimated material transparency level. Room-temperature continuous wave operation is also observed.Comment: 4 pages, 3 figure

Self-tuned quantum dot gain in photonic crystal lasers

We demonstrate that very few (1 to 3) quantum dots as a gain medium are sufficient to realize a photonic crystal laser based on a high-quality nanocavity. Photon correlation measurements show a transition from a thermal to a coherent light state proving that lasing action occurs at ultra-low thresholds. Observation of lasing is unexpected since the cavity mode is in general not resonant with the discrete quantum dot states and emission at those frequencies is suppressed. In this situation, the quasi-continuous quantum dot states become crucial since they provide an energy-transfer channel into the lasing mode, effectively leading to a self-tuned resonance for the gain medium.Comment: 4 pages, 4 figures, submitted to Phys. Re