Efficient illumination for microsecond tracking microscopy.

The possibility to observe microsecond dynamics at the sub-micron scale, opened by recent technological advances in fast camera sensors, will affect many biophysical studies based on particle tracking in optical microscopy. A main limiting factor for further development of fast video microscopy remains the illumination of the sample, which must deliver sufficient light to the camera to allow microsecond exposure times. Here we systematically compare the main illumination systems employed in holographic tracking microscopy, and we show that a superluminescent diode and a modulated laser diode perform the best in terms of image quality and acquisition speed, respectively.

Homoclinic snaking in a semiconductor-based optical system.

We report on experimental observations of homoclinic snaking in a vertical-cavity semiconductor optical amplifier. Our observations in a quasi-one-dimensional and two-dimensional configurations agree qualitatively well with what is expected from recent theoretical and numerical studies. In particular, we show the bifurcation sequence leading to a snaking bifurcation diagram linking single localized states to "localized patterns" or clusters of localized states and demonstrate a parameter region where cluster states are inhibited.

Transverse spatial structure of a high Fresnel number Vertical External Cavity Surface Emitting Laser.

The transverse spatial structure of an optically-pumped, Vertical External Cavity Surface Emitting Laser is investigated experimentally. The Fresnel number of the laser cavity is controlled with an intracavity lens. We show how the emission profile changes when passing from a low to a high Fresnel number configuration and analyze the RF spectrum of the total laser intensity.

Incoherent and coherent writing and erasure of cavity solitons in an optically pumped semiconductor amplifier.

Cavity solitons in semiconductor amplifiers were, from the beginning of their study and observation, obtained either spontaneously or in a controlled manner by local coherent excitation. We describe two experiments that demonstrate coherent and, we believe for the first time, incoherent writing and erasure of cavity solitons in an optically pumped vertical-cavity semiconductor amplifier by short optical pulses.

Optimization of the switch-on and switch-off transition in a commercial laser.

The response of a Class B laser to a rapid change in one of its parameters is known to be accompanied by delay and ringing. It has been theoretically and numerically shown that the transition can be modified by using adequate functional shapes for the control parameter (e.g.