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In JoVE (1)
Other Publications (2)
Articles by Karl Welna in JoVE
Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities
Christopher Paul Reardon1, Isabella H. Rey1, Karl Welna1, Liam O'Faolain1, Thomas F. Krauss1
1School of Physics & Astronomy, University of St Andrews
Other articles by Karl Welna on PubMed
Optics Express. Mar, 2009 | Pubmed ID: 19259180
We demonstrate beam deflection and multiple channel communication in free space optical communications using microprisms integrated directly onto an array of vertical cavity surface emitting lasers (VCSELs). The design and fabrication of such a transmitter is presented, and shown to achieve beam deflection of up to 10 degrees in a planar configuration. A location discovery application, for use within a distributed network, is put forward and analysed.
Optics Express. Dec, 2010 | Pubmed ID: 21165010
We present the first demonstration of frequency conversion by simultaneous second- and third-harmonic generation in a silicon photonic crystal nanocavity using continuous-wave optical excitation. We observe a bright dual wavelength emission in the blue/green (450-525 nm) and red (675-790 nm) visible windows with pump powers as low as few microwatts in the telecom bands, with conversion efficiencies of âˆ¼ 10 (-5) /W and âˆ¼ 10/ W(2) for the second- and third-harmonic, respectively. Scaling behaviors as a function of pump power and cavity quality-factor are demonstrated for both second- and third order processes. Successful comparison of measured and calculated emission patterns indicates that third-harmonic is a bulk effect while second-harmonic is a surface-related effect at the sidewall holes boundaries. Our results are promising for obtaining practical low-power, continuous-wave and widely tunable multiple harmonic generation on a silicon chip.