Coherence function control of Quantum Dot Superluminescent Light Emitting Diodes by frequency selective optical feedback.
Low coherent light interferometry requires broad bandwidth light sources to achieve high axial resolution. Here, Superluminescent Light Emitting Diodes (SLDs) utilizing Quantum Dot (QD) gain materials are promising devices as they unify large spectral bandwidths with sufficient power at desired emission wavelengths. However, frequently a dip occurs in the optical spectrum that translates into high side lobes in the coherence function thereby reducing axial resolution and image quality. We apply the experimental technique of frequency selective feedback to shape the optical spectrum of the QD-SLD, hence optimizing the coherence properties. For well-selected feedback parameters, a strong reduction of the parasitic side lobes by a factor of 3.5 was achieved accompanied by a power increase of 40% and an improvement of 10% in the coherence length. The experimental results are in excellent agreement with simulations that even indicate potential for further optimizations.
Blazek
Martin
M
Institute of Applied Physics, Darmstadt University, D-64289 Darmstadt, Germany. martin.blazek@physik.tu-darmstadt.de
Elsässer
Wolfgang
W
Hopkinson
Mark
M
Resneau
Patrick
P
Krakowski
Michel
M
Rossetti
Mattia
M
Bardella
Paolo
P
Gioannini
Mariangela
M
Montrosset
Ivo
I
D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D007089:Image Enhancement / Q000295:instrumentation*; D007368:Interferometry / Q000295:instrumentation*; D008027:Light; D008029:Lighting / Q000295:instrumentation*; D008163:Luminescent Measurements / Q000295:instrumentation*; D008962:Models, Theoretical; D055096:Optical Devices; D045663:Quantum Dots; D012542:Scattering, Radiation; D012666:Semiconductors; D041623:Tomography, Optical Coherence / Q000295:instrumentation*