We report the observation of single and multiple vortex solitons in a self-focusing dissipative system, a broad-area vertical-cavity surface-emitting laser (VCSEL) with frequency-selective feedback by a volume Bragg grating. They are bistable and the transitions between different soliton structures are analysed. The observations qualitatively verify theoretical predictions based on simplified models for a semiconductor laser with frequency-selective feedback.

We report on a simple method with a high spectral and spatial resolution for mapping variations in the cavity resonance of a plano-planar broad-area laser based on frequency-selective feedback. The demonstration experiment uses a vertical-cavity surface-emitting-laser (VCSEL), in which growth induced inhomogeneities are of particular importance. It relies only on a standalone laser with a narrow-bandwidth passive filter avoiding the need for an expensive tunable laser or high-resolution spectrometer.

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In this paper we present an evolution of the single-pixel camera architecture, called 'pushframe', which addresses the limitations of pushbroom cameras in space-based applications. In particular, it is well-suited to observing fast moving scenes while retaining high spatial resolution and sensitivity. We show that the system is capable of producing colour images with good fidelity and scalable resolution performance. The principle of our design places no restriction on the spectral range to be captured, making it suitable for wide infrared imaging.