Tuning optical modes in slab photonic crystal by atomic layer deposition and laser-assisted oxidation

Abstract

The authors experimentally investigate the effects of atomic layer deposition (ALD) and laser-assisted oxidation on the optical modes in GaAs L3 photonic crystal air-bridge cavities, using layers of InAs quantum dots as internal light source. Four distinct optical mode peaks are observed in the photonic bandgap and they show different wavelength-redshifts (0–6.5 nm) as the photonic crystal surface is coated with an Al2O3 layer (0–5.4 nm thick). Numerical finite-difference time-domain (FDTD) simulations can well-reproduce the experimental result and give insight into the origin of the shifts of modes with different spatial profiles. By combining the ALD coating with in situ laser-assisted oxidation, we are able to both redshift and blueshift the optical modes and we attribute the blueshift to the formation of a GaAs-oxide at the expense of GaAs at the interface between GaAs and the Al2O3 layer. This result can be quantitatively reproduced by including a GaAs-oxide layer into the FDTD model. Selective etching experiments, confirm that this GaAs-oxide layer is mainly at the interface between GaAs and Al2O3 layers.

Integrated all‐optical switch with 10 ps time resolution enabled by ALD

“… when average power was raised. The conformal growth of Al 2 O 3 effectively prevents oxidation, as already shown on photonic crystal structures . We confirm that ALD‐coated samples are remarkably stable even under exposure to intense optical flux.…”

Modification and Resonance Tuning of Optical Microcavities by Atomic Layer Deposition

“…Since 2003, photonic crystals have been intensively investigated for their potential to confine, as well as to guide, light. Many researchers have demonstrated that ALD allows rapid and flexible fabrication of photonic crystals, and opals …”

“…The ALD approach for self‐assembled 3D photonic crystals and opal structures has been extended to include a broad variety of materials. Ta 3 N 5 , ZnO, GaAs, Al 2 O 3 , TiO 2 , and ZnS have all been used to produce multilayer inverse opal structures. The wavelength of the peak Bragg reflection was observed to shift to progressively longer wavelengths versus the ALD thickness of inorganic thin films .…”

“…d) Color‐coded µ‐PL intensity map showing the mode peaks as a function of ALD step. One ALD step corresponds to 0.9 nm Al 2 O 3 coating (Reproduced with permission . Copyright 2011, American Institute of Physics).…”

Spectral tuning of a three-dimensional photonic-bandgap waveguide signature by silica atomic-layer deposition

“…This method relies on atomic layer deposition (ALD) to infiltrate the waveguide structures with thin layers of dielectric. While ALD has previously been used to adjust geometric parameters of bulk photonic crystals [14] and to tune optical modes in two-dimensional photonic crystal slabs [15,16], this is the first time it is successfully employed to induce systematic changes in the optical properties of a 3D PBG waveguide. In principle the method is not limited to the waveguides considered here but it can be applied to any 3D photonic crystal defect structure suitable for infiltration, including point-defect cavities.…”