P. Kelkar

Room‐temperature optically pumped blue‐green vertical cavity surface emitting laser

Surface emitting laser operation at room temperature at λ=496 nm by ps pulsed optical injection has been demonstrated in a II–VI separate confinement heterostructure containing three 80 A thick (Zn,Cd)Se quantum wells (QW). The vertical cavity was formed by low loss, dielectric, distributed Bragg mirrors, yielding a quality factor for the structure of approximately Q≊2000. The room‐temperature threshold excitation corresponds to an absorbed optical energy density of 1.4 μJ/cm2 or, equivalently, to an estimated electron‐hole pair density of 1×1012 cm−2. At T=200 K, quasicontinuous wave operation was obtained at an average output power of up to 1 mW and an output/input conversion efficiency of 20%.

Gain and dynamics in ZnSe-based quantum wells

Abstract Gain spectroscopy and population dynamics are investigated in ZnCdSe/ZnSSe/ZnMgSSe separate confinement heterostructure (SCH) diode lasers. Both steady state and time-resolved methods are applied to characterize the dense electron-hole pair gas in the ZnCdSe active quantum well (QW) region from 77 K to room temperature. Effects due to the carrier interaction with optical phonons and electron-hole Coulomb effects are discussed. A direct measurement of the carrier lifetime at pair densities under typical laser conditions has also been obtained.

Quantum microcavities in II–VI semiconductors: strong coupling regime in vertical cavity lasers

Abstract Enhanced light-matter coupling effects are striking in II–VI quantum well microresonators, with the normal mode (Rabi) splitting exceeding 10 meV per quantum well at the exciton resonance in ZnSe-based heterostructures. Such a dominating imprint of the mixed exciton-photon modes extends to high electron-hole pair densities, including the regime of vertical cavity laser operation. We present results from gain spectroscopy to show how the composite photon-exciton oscillator supplies optical gain for a laser operating beyond the conventional perturbative regime.