EUROSTARS project E!10524
"High Power Composites of Edge Emitting Semiconductor Lasers" (HIP-Lasers)

Project status

01.10.2016-31.03.2019

Overview

High power high brightness edge-emitting broad-area semiconductor (BAS) lasers are compact, efficient and reliable light sources playing a crucial role in different laser technologies, such as free space communications, three-dimensional printing, marking, materials processing, pumping fiber amplifiers, or optical frequency conversion. BAS lasers and amplifiers have a relatively simple geometry allowing an efficient current injection through a broad electric contact on the top of the device and can operate at high power (tens of Watts) regimes. However, BAS devices have one serious drawback: operated at high power, they suffer from a low beam quality due to simultaneous irregular contributions of different lateral and longitudinal optical modes. As a result, the emitted optical beam is irregular, has undesirable broad optical spectra, and large divergence. Thus, a quality improvement of the beam generated by BAS lasers is a critical issue of the modern semiconductor laser technology.

The main aim of the joint research project is to build a compact semiconductor laser platform emitting high power/brightness high spatial quality beams. For this reason, we intend to maximize the beam brightness of individual lasers through the use of novel intracavity photonic crystal (PhC) spatial filters and to combine the individual laser beams by a new spectral multiplexing technique. The target of the whole project is a new generation of compact diode laser platforms capable of emitting up to 1kW (without amplifier) beams with a beam parameter product (BPP) between 2 and 3 mm mrad.

The tasks of the WIAS within this project is modeling, simulation, analysis, and optimization of edge-emitting broad-area semiconductor lasers and laser arrays with intracavity spatial filtering elements. Namely, we shall look theoretically for the optimal laser diode - PhC filter configurations admitting a significant improvement of the emitted field quality as well as perform modeling and optimization simulations of the laser arrays with a specially designed beam combining scheme.

Our modeling approach is based on the 2 (space) + 1 (time) dimensional traveling wave model which is determined by a pair of PDEs for the complex slowly varying amplitudes of the counterpropagating optical fields nonlinearly coupled to the diffusive carrier rate equation in the active zone. For the numerical solution of the resulting large-scale problem, we use our software tool BALaser. The parallel algorithms exploited by this software allow achieving up to 50 times speedup of numerical calculations, what is crucial when performing parameter optimization of the considered devices. For example, a typical single-parameter study on the parallel computer cluster can be performed over a single night instead of more than one-month calculations on a single processor computer. For optimization simulations of a laser with an intracavity PhC filter, we need to extend our existing model by new efficient models describing field propagation through the filtering element. This can be done either by using a several-Bloch-mode approximation of the optical fields within this filtering element or using the straightforward calculation of the paraxial optical field propagation through the photonic crystal. Our preliminary simulations and analysis of periodically modulated broad area semiconductor amplifiers allow us expecting an improvement of the beam quality in semiconductor laser devices with properly designed intracavity photonic crystal filters.

The WIAS is a full partner of this joint research project. Other project partners are Monocrom [Barcelona, Spain] (project coordinator), Femtika [Vilnius, Lithuania], Raab-Photonik GmbH [Potsdam, Germany], and the Nonlinear Dynamics, Nonlinear Optics and Lasers group of the Universitat Politecnica de Catalunya [Barcelona, Spain] (subcontracted by Monocrom).

Own related works and software

• M. Radziunas, ''Modeling and simulations of broad-area edge-emitting semiconductor devices'', to appear in International Journal of High Performance Computing Applications. WIAS-Preprint (2292), 2016.
• W.W. Ahmed, S. Kumar, R. Herrero, M. Botey, M. Radziunas, and K. Staliunas, ''Stabilization of flat-mirror vertical external-cavity-surface emitting lasers by spatiotemporal modulation of pump profile'', Phys. Rev. A 92, art. no. 043829, 2015.
• M. Radziunas, R. Herrero, M. Botey, and K. Staliunas, ''Far field narrowing in spatially modulated broad area edge-emitting semiconductor amplifiers'', J. Opt. Soc. Am. B, 32(5), pp. 993-1000, 2015. WIAS-Preprint, (2088).
• M. Radziunas, R. Čiegis, ''Effective numerical algorithm for simulations of beam stabilization in broad area semiconductor lasers and amplifiers'', Math. Model. Anal. 19(5), pp. 627-646, 2014.
• M. Radziunas, M. Botey, R. Herrero, K. Staliunas, ''Intrinsic beam shaping mechanism in spatially modulated broad area semiconductor amplifiers'', Appl. Phys. Lett. 103(13), 132101, 2013. WIAS-Preprint (1790).
• R. Herrero, M. Botey, M. Radziunas, K. Staliunas, ''Beam shaping in spatially modulated broad area semiconductor amplifiers'', Optics Letters 37(24), pp. 5253-5255, 2012.
• R. Čiegis, M. Radziunas, ''Effective Numerical Integration of Traveling Wave Model for Edge-Emitting Broad-Area Semiconductor Lasers and Amplifiers'', Math. Model. Anal. 15(4), pp. 409-430, 2010.
• A. Jechow, M. Lichtner, R. Menzel, M. Radziunas, D. Skoczowsky, A. Vladimirov, ''Stripe-array diode-laser in an off-axis external cavity: Theory and experiment'', Optics Express 17(22), pp. 19599-19604, 2009. WIAS-Preprint, (1442).
• M. Spreemann, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, ''Measurement and Simulation of Distributed-Feedback Tapered Master-Oscillators Power-Amplifiers'', IEEE J. of Quantum Electronics 45(6), pp. 609-616, 2009.
• BALaser: a software tool for simulation of dynamics in Broad Area semiconductor Lasers.