Frankfurt 2006 – scientific programme
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Q: Quantenoptik und Photonik
Q 59: Photonische Kristalle IV
Q 59.7: Talk
Thursday, March 16, 2006, 12:40–12:55, HI
Mode interaction in coupled photonic crystal waveguides — •Nico Schorr1, Helmut Scherer1, Martin Kamp1, Alfred Forchel1, Klemens Janiak2, and Helmut Heidrich2 — 1Technische Physik, Am Hubland, D-97074 Würzburg, Germany — 2Heinrich-Hertz-Institut, Einsteinufer 37, D-10587 Berlin, Germany
The intricate mode structure of photonic crystal (PhC) waveguides makes them versatile building blocks for applications such as spectral filters, power splitters and similar devices. We have investigated the interaction of modes in coupled PhC waveguides. The photonic crystal is realized as a hexagonal lattice of air holes etched into a planar waveguide layer. The waveguides are defined by three missing rows of holes from this lattice. They have a length of 30 lattice periods and are separated by PhC blocks with varying thickness (one to three rows of holes).
The structures are fabricated from passive InP/InGaAsP slab waveguides, which consist of a 420 nm thick quaternary waveguide core grown on an InP substrate and capped by a 200 nm thick InP cladding layer. The PhC patterns with periods in the range of 350 to 420 nm are etched to a depth of more than 3.5 µ m into the semiconductor. A tunable laser source (λ = 1480 − 1580 nm) is used to probe the structures.
The power at the end of the original waveguide shows a clear drop in certain spectral regions, whereas the power in the coupled waveguide increases. This is caused by coupling of light from the fundamental waveguide mode to a higher order mode, which in turn transfers the light to the coupled waveguide.