The development of optical gain in chemically synthesized semiconductor nanoparticles (nanocrystal quantum dots) has been intensely studied as the first step toward nanocrystal quantum dot lasers. We examined the competing dynamical processes involved in optical amplification and lasing in nanocrystal quantum dots and found that, despite a highly efficient intrinsic nonradiative Auger recombination, large optical gain can be developed at the wavelength of the emitting transition for close-packed solids of these dots. Narrowband stimulated emission with a pronounced gain threshold at wavelengths tunable with the size of the nanocrystal was observed, as expected from quantum confinement effects. These results unambiguously demonstrate the feasibility of nanocrystal quantum dot lasers.

http://science.sciencemag.org/content/sci/290/5490/314.full.pdf

Optical gain and stimulated emission in nanocrystal quantum dots.

Influences on the semiconductor laser properties of external optical feedback, i.e., return of a portion of the laser output from a reflector external to the laser cavity, have been examined. Experimental observations with a single mode laser is presented with analysis based on a compound cavity laser model, which has been found to explain essential features of the experimental results. In particular, it has been demonstrated that a laser with external feedback can be multistable and show hysteresis phenomena, analogous to those of non-linear Fabry-Perot resonator. It has also been shown that the dynamic properties of injection lasers are significantly affected by external feedback, depending on interference conditions between returned light and the field inside the laser diode.

External optical feedback effects on semiconductor injection laser properties

Slow light with a remarkably low group velocity is a promising solution for buffering and time-domain processing of optical signals. It also offers the possibility for spatial compression of optical energy and the enhancement of linear and nonlinear optical effects. Photonic-crystal devices are especially attractive for generating slow light, as they are compatible with on-chip integration and room-temperature operation, and can offer wide-bandwidth and dispersion-free propagation. Here the background theory, recent experimental demonstrations and progress towards tunable slow-light structures based on photonic-band engineering are reviewed. Practical issues related to real devices and their applications are also discussed. The unique properties of wide-bandwidth and dispersion-free propagation in photonic-crystal devices have made them a good candidate for slow-light generation. This article gives the background theory of slow light, as well as an overview of recent experimental demonstrations based on photonic-band engineering.

/pdf/slow-light-in-photonic-crystals-59fjoaj79v.pdf

Slow light in photonic crystals

1. Introduction and overview 2. Film stress and substrate curvature 3. Stress in anisotropic and patterned films 4. Delamination and fracture 5. Film buckling, bulging and peeling 6. Dislocation formation in epitaxial systems 7. Dislocation interactions and strain relaxation 8. Equilibrium and stability of surfaces 9. The role of stress in mass transport.

Thin Film Materials: Stress, Defect Formation and Surface Evolution

An overview of analog microwave photonics will be presented. The performance requirements for externally-modulated analog microwave photonic links will be reviewed with specific emphasis placed on modulator efficiency, laser noise, detected photocurrent, and link linearity.

http://ieeexplore.ieee.org/iel5/6387506/6403300/06403360.pdf

Microwave photonics

Suppression of mode hopping noise caused by external reflection in dynamic single mode (DSM) lasers

Direct modulation properties of BIG-DBR-DSM lasers were investigated by measuring both the time-averaged and the time-resolved spectra. A high side-mode-suppression ratio of more than 30 dB was obtained from time-averaged measurements with the modulation frequency in the range of 250 MHz-2 GHz. The dynamic wavelength shift at - 3 dB level obtained from both time-averaged and time-resolved measurements was less than 2 A. Time-resolved measurements showing an oscillatory behavior of the dynamic wavelength shift with both red and blue shifts were also observed. Calculations based on a numerical solution of the rate equations, which agreed quantitatively with the measurement, indicate a line width enhancement factor estimated to lie between 3.5 and 5.5.

Yasuharu Suematsu

Papers

Suppression of mode hopping noise caused by external reflection in dynamic single mode (DSM) lasers

Spectral behavior of 1.5 µm BIG-DBR-DSM lasers

Bandwidths of single mode optical fibers

Enhancement effect of high-frequency noise of injection lasers with reflected waves due to direct modulation

Amplification Characteristics of Integrated Twin-Guide Laser Amplifier

Yasuharu Suematsu

Papers

Suppression of mode hopping noise caused by external reflection in dynamic single mode (DSM) lasers

Spectral behavior of 1.5 &#181;m BIG-DBR-DSM lasers

Bandwidths of single mode optical fibers

Enhancement effect of high-frequency noise of injection lasers with reflected waves due to direct modulation

Amplification Characteristics of Integrated Twin-Guide Laser Amplifier

Spectral behavior of 1.5 µm BIG-DBR-DSM lasers