Faculté des sciences

Efficient beamshaping of high-power diode lasers using micro-optics

Herzig, Hans-Peter ; Schilling, Andreas ; Stauffer, Laurent ; Vokinger, Urs ; Rossi, Markus

In: Gradient Index, Miniature, and Diffractive Optical Systems II (Proceedings of SPIE), 2001, vol. 4437, p. 134-141

We designed, fabricated and characterized a micro-optical beamshaping device, intended to optimize the coupling of an incoherent, linearly extended high-power diode-laser into a multimode fiber. The device uses two aligned micro-optical elements (DOEs) in combination with conventional optics. With a first prototype we achieved an overall efficiency of 28 %. Straightforward improvements, like... More

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    Summary
    We designed, fabricated and characterized a micro-optical beamshaping device, intended to optimize the coupling of an incoherent, linearly extended high-power diode-laser into a multimode fiber. The device uses two aligned micro-optical elements (DOEs) in combination with conventional optics. With a first prototype we achieved an overall efficiency of 28 %. Straightforward improvements, like antireflective coatings and the use of graytone elements, should lead to an efficiency of about 50 %. The device is compact and the fabrication is suited for mass production at low cost. We applied three different technologies for the fabrication of the micro-optical elements and compared the performance. The technologies were: direct laser writing, multiple projection photolithography in combination with reactive ion etching (RIE) in fused silica, and high-energy-beam-sensitive (HEBS) glass graytone lithography in photoresist. We found that the refractive type elements (graytone) yield better efficiency for large deflection angles, while diffractive elements give intrinsically accurate deflection angles.