Optical coupling of an active microdisk to a passive one: effect on the lasing thresholds of the whispering-gallery supermodes.

The lasing spectra and thresholds of a selectively pumped photonic molecule composed of two microdisks is investigated using effective index approximation and full-wave 2-D electromagnetic equations. The lasing eigenvalue problem formulation is used to find modal frequencies and threshold values of material gain. The influence of the optical coupling between active and passive microdisks on the lasing eigenvalues and directionalities of emission is studied.

Subwavelength terahertz spin-flip laser based on a magnetic point-contact array.

We present a theoretical design for a single-mode, truly subwavelength terahertz disk laser based on a nanocomposite gain medium comprising an array of normal-metal/ferromagnetic (FM) point contacts embedded in a thin dielectric layer. Stimulated emission of light occurs due to spin-flip relaxation of spin-polarized electrons injected from the FM side of the contacts. Ultrahigh electrical current densities in the contacts and a dielectric material with a large refractive index, neither condition being achievable in conventional semiconductor media, enables the thresholds of lasing to be overcome for the lowest-order modes of the disk, making single-mode operation possible.

Optical fields of the lowest modes in a uniformly active thin subwavelength spiral microcavity.

A numerical study is presented of several lowest in frequency modes in a spiral microlaser. The modes in an arbitrarily shaped active cavity are considered as solutions to the two-dimensional eigenproblem for the Muller boundary-integral equations. After discretization using the Nyström-type algorithm, the eigenvalues are found in terms of frequency and material-gain threshold.

Lasing frequencies and thresholds of the dipole supermodes in an active microdisk concentrically coupled with a passive microring.

The lasing spectra and threshold values of material gain for the dipole-type supermodes of an active microdisk concentrically coupled with an external passive microring are investigated. TE polarized modes are treated accurately using the linear electromagnetic formalism of the 2-D lasing eigenvalue problem (LEP) with exact boundary and radiation conditions. The influence of the microring on the lasing frequencies and thresholds is studied numerically, demonstrating threshold reduction opportunities.

Threshold reduction in a cyclic photonic molecule laser composed of identical microdisks with whispering-gallery modes.

Lasing modes in cyclic photonic molecules (CPMs) composed of several identical thin semiconductor microdisks in free space are studied in a linear approximation. Maxwell's equations with exact boundary conditions and the radiation condition at infinity are considered as a specific eigenvalue problem that enables one to find natural frequencies and threshold gains. It is demonstrated that careful tuning of the distance between the disks in CPMs is able to drastically reduce the lasing thresholds of the whispering-gallery modes having small azimuth indices.