We have designed a structure for a 2×2 silica-based optical waveguide switch that is based on a thermocapillarity effect. This switch can use the reflection walls on both sides of the slit, because the Goos–Hänchen shift effect was taken into account when the structure of the waveguides and the slit was designed. This switch can provide a cross/bar function through a single element, and the measured reflection losses in the reflection walls on both sides of the slit were consistent. The loss was comparable to the insertion loss of a Mach–Zender-interferometer-type thermo-optic switch.
We investigate the transmission properties of Fabry–Pérot microcavities made of metal mirrors containing the organic dye molecule, generally called Lemke. We synthesized Lemke dye and fabricated the microcavities by using simple vacuum evaporation and spin-coating methods. The vacuum Rabi splitting energy increases in proportion to the square root of the absorption coefficient of the cavity layers and exceeds 1 eV at maximum. The ratio of the vacuum Rabi splitting energy to the matter transition energy reaches 0.42, so we consider that the ultrastrong-coupling regime was attained. The dispersion relation is reasonably interpreted by using the full Hopfield Hamiltonian.
GaAs dry etching using reactive–fast-atom beam etching to obtain an etched mirrorlike surface is investigated. An etch rate of 0.1–0.6 μm/min is obtained when Cl2 gas is used, which is 50–100 times faster than when Ar gas is used. The etch rate ratio between GaAs and photoresist AZ-1350J is more than 30. As a result, a trench with a depth of more than 10 μm and a width of less than 2 μm is easily fabricated under the etch conditions of a Cl2 gas pressure of 5–6.5×10−2 Pa, an accelerate voltage of 1.5–1.8 kV, and a substrate temperature of about 100 °C. The radiation damage caused by this etching is very small, and it is similar to that caused by wet chemical etching, in spite of the relatively higher accelerator voltage. The thickness of an induced damage layer is only 150 Å. It is found that the radiation damage induced by reactive–fast-atom beam etching decreased with an increase of the etch rate. It is confirmed that vertical, smooth, damage-free etching can be easily attained with reactive–fast-atom beam etching.
We have developed a new high-power fast-atom beam (FAB) source by modifying a McIlraith-type ion source. The beam current density emitted from a source with an electromagnet and multiaperture grid is about ten times higher (up to 1 mA/cm2) than that emitted from a conventional source. Silicon dioxide can therefore be etched at 60 nm/min when CF4 gas is used, or about six times faster than by using a conventional source with the same discharge current. The beam neutralization coefficient of the new FAB source is nearly 100%. We have used this FAB source to etch Si, SiO2, GaAs, and other compound materials. We could easily etch an anisotropic profile (nearly vertical with an aspect ratio of more than 10 for a 0.6 μm L&S pattern), etch at a high rate (0.3–0.5 μm/min), and etch with high selectivity (GaAs:resist =30:1). We also fabricated a SiO2 fine pattern in 0.6 μm L&S by using CF4 reactive-fast-atom beam etching. The uniformity of the etch depth is about ±5% over a 4-in. wafer. Surface radiation damage (total oxide charge) caused by FAB bombardment of the SiO2/Si structure is very close to that of reference (not etched) samples. This damage is significantly less than that caused by ion beam bombardment under almost the same radiation conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.