Experimental study of speckle patterns generated by low-coherence semiconductor laser light

Abstract

Paper published as part of the special topic on Instabilities and Nonequilibrium Structures ARTICLES YOU MAY BE INTERESTED INDoes following optimized routes for single cars improve car routing? Chaos:

Nanolasers with Feedback as Low-Coherence Illumination Sources for Speckle-Free Imaging: A Numerical Analysis of the Superthermal Emission Regime

“…Strengthening this case, the experimental measurement of the emission spectrum in a nanolaser, through the first-order autocorrelation g (1) , showed broadband emission in concomitance with superpossonian photon statistics [60]. This feature, normally considered an intrinsic disadvantage of the smallest devices, turns here into an advantage, rendering the realization of low-coherence beams easier than in standard semiconductor lasers [33].…”

“…Technological development has enabled stronger emission in a cone that can escape the material, but the collection optics and the transfer of the emission to the sample to be illuminated remains more challenging than with self-collimated laser light. As a result, the laser naturally offers a larger amount of exploitable power-for the same amount of provided energywithout additional efforts; thus, explaining why the oxymoron low-coherence laser light has attracted so much interest [18][19][20][21][23][24][25][26][28][29][30][31][32][33]. At variance with what is known in macroscopic lasers, Figure 2a shows that the nanolaser output does not entirely consist of stimulated photons when P > P th .…”

“…New cavity geometries [28,29], optical feedback, other dynamics [25,[30][31][32] and random lasers and supercontinuum sources [20] were studied as low-coherence sources. Recently, an experimental investigation reported on the speckle patterns obtained from modulated microlasers and coupled-cavity nanolasers, where unexpected non-Rayleigh statistics could be related to ultrafast temporal fluctuations [33]. There the authors examine, in parallel, techniques to reduce emission coherence in an edge-emitting semiconductor laser and in the coupled nanolasers.…”

“Phase transitions” in small systems: Why standard threshold definitions fail for nanolasers

“…The interest behind the scale reduction is twofold: on the one hand enabling applications which range from faster modulation speed for telecommunications [4,[27][28][29][30][31][32][33] to high-density optical chips which hold high hopes for lower energy consumption in datacenters [30,[34][35][36][37][38]; on the other hand gaining a clear understanding of the physics of nanodevices to enable controlled applications in the field of fully or partially coherent sources [23,24], such as illumination [39] or sensing [40].…”

Compound Speckle Reduction in Laser Imaging Systems by Using a Vibrating Multimode Fiber and a Tracked Moving Flexible DOE Loop

“…The methods to reduce laser coherence include wavelength diversity, polarization diversity and angle diversity. For wavelength diversity, the use of laser diode arrays or a broadband laser is usually required to reduce speckles [6]- [8]; this increases the cost and complexity of light sources. The use of polarization diversity to reduce speckles is generally limited because lasers have only two polarization states [9].…”