I spent a while punching author names from Photonics West 2010 into google today. I soon realized that I was likely not alone in this pursuit and would be well advised to update this website to be relevant to the new potential visitors here over the course of the next week.

If you are in San Francisco, and attending the conference, and have found this page, I’d like to invite you to attend my talk on Thursday at 11:20 in room 234 (Mezzanine). My talk is entitled “Photonic Crystal Switching by the electrophoretic movement of dye ions” and is part of the session on “Novel effects and Applications in Photonic Crystal Structures” within the “Photonic and Phononic Crystal Materials and Devices IX“. Relevant information is on pages 238-240 of the Technical Program.

Now that I’ve located all this spatially, temporally, and categorically I’d probably be wise to briefly outline the paper:

ABSTRACT: Glancing angle deposition (GLAD) facilitates the fabrication of nanostructured thin films with varying density, using a motion control algorithm governing substrate movements during film growth, which engineerings the film structure. Film architectures for specific optical applications including photonic crystals are easily produced with GLAD. A challenge in the photonic crystal field has been the realization of in-situ control of optical characteristics. We have demonstrated partial control of stopband optical characteristics using an electric field in a GLAD 1D photonic crystal by the electrophoretic movement of absorbing dye ions.

Authors: Joshua D. Krabbe, Univ. of Alberta (Canada); Michael J. Brett, Univ. of Alberta (Canada) and National Institute for Nanotechnology (Canada)

With a bit more elaboration:

The basic premise of this work is that the movement of absorbing dye ions into and out of a porous photonic crystal yields a means by which the optical properties of the stopband of the photonic crystal may be modified. The device structure (shown below) is probed for reflectance optical properties from the top surface within the operating region (delimited by dashed lines). The photonic crystal is deposited on a transparent conducting oxide film and when the sandwich structure is completed with an identical counter electrode the device becomes electrically addressable. A dissociating dye (Methylene Blue) is used and when a positive voltage (top with respect to bottom) is applied the cations of the dye (absorbing species) are driven out of the photonic crystal. Reversal of the voltage attracts these cations and absorbing dye species accumulate in the photonic crystal.

Note: this image is (very!) not to scale.

As you likely have already anticipated, the presence of absorbing species within the photonic crystal has an inhibiting effect on the reflectance. Changing the dye concentration affects the probability of photon-dye interaction. The response of reflectance properties with addressing voltage, and an examination of the time response of optical properties to electrical switching of the device will be presented; along with an elaboration of the GLAD technique used to fabricate the porous photonic crystal that forms the basis of the device.

If you can’t attend, the proceedings will be published in 2-4 weeks.