I am currently writing about the latest research from Mark Kuzyk – famed discoverer of the Kuzyk effect also known as the Kuzyk quantum gap. He and his colleagues have discovered a whole new class of compounds that could eventually revolutionize optical information processing (more on that in the January issue of Intute Spotlight). Anyway, he told me that getting a stronger and stronger optical, so-called non-linear response, from the materials he and his colleagues are devising will “require deliberate and painstaking molecular design and synthesis.”
But, there are also some even more serious obstacles than acumen in synthetic chemistry. He explained that molecules that have a large nonlinear-optical susceptibility, i.e. are perfect for the job in hand are often rather unstable too. Now, obviously that’s something that you have to avoid if you’re going to incorporate a molecule into a device (ask Richard Friend who has spent the last decade and a half working with his chemist colleagues to make their plastic LEDs not only bright and useful but as long-lived as possible).
All compounds are created with an intrinsic stability but some are created more unstable than others. Kuyzk told me that he had once suggested to a chemist colleague when he was at Bell Labs in the 1980s that he should try and make a specific molecule the structure of which should have produced a large optical response. “He laughed when he saw the structure,” Kuyzk said, “claiming that it would be much more explosive than TNT.” Now, I wouldn’t have liked to have been the project student charged with synthesising that nonlinear optical compound without some understanding of the stability, or otherwise, of conjugated organic bonding systems.
On a related matter, photo-stability (as opposed to thermal stability), Kuzyk also revealed to me that several years ago, a student in his group, Brent Howell, serendipitously stumbled upon a dye-doped polymer system that not only acted as a laser but recovered from photo-degradation if the system was left in the dark for a couple of days.
Furthermore, the material could be hardened to photodegradation by cycling through degradation and recovery. “We have proposed a model of the mechanisms, and are still doing experiments to test our hypothesis,” Kuyzk adds. A paper that shows recovery in two-photon absorbing materials appears in Optics Letters.