Reversible tuning of photonic crystal cavities using photochromic thin films

Abstract

We demonstrate reversible tuning of a photonic crystal cavity resonance using a thin photochromic film composed of spiropyran and polymethylmethacrylate that serves as a photosensitive cladding layer. Exposure of spiropyran to ultraviolet light results in smooth redshift of the cavity resonance that can be reversed by exposure to visible wavelength light. We achieve a reversible resonance shift of up to 2.7 nm, which can be performed locally on individual cavities. The resonance shift over multiple successive UV and visible light exposures is studied to determine the repeatability of the photochromic film.

Anisotropic crystallization in solution processed chalcogenide thin film by linearly polarized laser

“…(black curve in Figure 3d), this temperature matches the expected glass transition (Tg) (Fig. 3e) at 6 which the material becomes liquid like from the glassy state. Tg in raw material is measured to be near 191.…”

Deterministic generation of entanglement between a quantum-dot spin and a photon

“…We also assume that the transition |↑ ↔ |⇑ is resonant with the cavity mode, while the other transition is detuned. In a real experiment, a variety of methods can exist to tune the desired quantum-dot transition to the cavity, including varying temperature [28,29], changing the magnetic field [30], applying strain [31], or tuning the cavity resonance [32,33].…”

Strain tuning of quantum dot optical transitions via laser-induced surface defects

“…Techniques are therefore needed to fine-tune the optical properties of microcavities and match the resonance frequencies of the emitter and the cavity. Permanent or reversible frequency shifting of the resonances of photonic crystal cavities can be achieved with different tools: wet chemical digital etching 19 , photodarkening of a thin chalcogenide glass layer 20 or a photo-chromic thin film 21 deposited on top of the device, atomic force microscope nano-oxidation of the cavity surface 22 , infiltration of liquids 23,24 or absorption of xenon 25 . Such techniques, however, only work for photonic crystals, where the cavity is on the surface of the device and can be easily accessed.…”