L.T.H. Hilderink

Plasma enhanced chemical vapor deposition silicon oxynitride optimized for application in integrated optics

Silicon Oxynitride (SiON) layers are grown from SiH4/N2, NH3 and N2O by Plasma Enhanced Chemical Vapor Deposition (PECVD). The process is optimized with respect to deposition of layers with excellent uniformity in the layer thickness (δd<1%), high homogeneity of the refractive index (Δn=2–7×10−4) and good reproducibility of the layer parameters. The optical losses of slab-type waveguides is determined to be as low as 0.2 dB/cm at 632.8 nm wavelength. Due to absorption of N–H and Si–H vibrational overtones, the optical losses in the third telecommunication window, around 1550 nm, is increased to about 2 dB/cm for low index layers. By an anneal step, however, the hydrogen content of the films can be reduced as is confirmed by IR-spectroscopy and the optical losses decrease to below 0.2 dB/cm. Based on the optimized PECVD SiON technology, a layer structure fulfilling the strong requirements of telecommunication devices, is designed for operation at 1550 nm wavelength. This structure, consisting of a SiON core layer (n=1.4857) surrounded by thick oxide cladding layers (n=1.4637), has the potential for realization of channel waveguides allowing for low-loss bends with a small bending radius and high fiber-to-chip coupling efficiency.

Silicon Oxynitride A Versatile Material for Integrated Optics Applications

Silicon oxynitride is a very attractive material for integrated optics application, because of its excellent optical properties (~e.g. optical loss below 0.2 dB/cm!, the large refractive index range ~between 1.45 for silicon oxide and 2.0 for silicon nitride), and last but not least, the availability of reliable, low-cost fabrication technologies. Since good uniformity and reproducibility of the layers is extremely important for integrated optics applications, we have optimized the plasma-enhanced chemical vapor deposition and low-pressure chemical vapor deposition technologies of silicon oxynitride with respect to these requirements. Over a 50x50 mm area on a 3 inch wafer, an inhomogeneity of the refractive index of Dn<5E-3 and a nonuniformity of the layer thickness of < 1% can be obtained. Furthermore, new challenges such as the conditioning of the reactor, in order to guarantee process reproducibility in the same order of magnitude, are discussed. The high optical loss of silicon oxynitride in the third telecommunication window (wavelength range 1530-1605 nm), which is caused by the overtones of the Si-H and N-H bonds, was decreased by thermal treatment. Silicon oxynitride waveguides having a refractive index of 1.48 and an optical loss below 0.2 dB/cm (at 1550 nm) were realized.

Low-cost and low-loss multimode waveguides of photodefinable epoxy

To satisfy the urgent need for low-cost multimode planar waveguides, we developed photodefined, multimode-fiber compatible waveguides with low-cost commercially available epoxies showing low losses from 550 to 1100 nm and around 1300nm

Granular YBaCuO films prepared by metalorganic chemical aerosol deposition technology

Fine-grain thin superconducting films can be prepared by metalorganic Chemical Aerosol Deposition Technology (CADT). In this paper, we present the preparation and properties of YBa2Cu3O7-x films on the different substrates, Si and SrTiO3 (100). It is shown that the zero-resistance temperature (Tc,0) of the films on SrTiO3 substrates is about 90 K, and the critical current density (Jc) at 77 K is above 104 A/cm2. In addition, these films exhibit significant grain-boundary weak link behaviour, which is very promising for applications in electronic devices.

Polymeric components for telecom and datacom

Polymeric optical waveguide components offer attractive properties for applications in optical telecom and datacom systems. These are high speed for electro-optic modulators, low power dissipation for thermo-optic (digital) switches and low-cost for all active and passive components. We report on active and passive components realized by utilizing polymer-specific attractive techniques such as planarizing spincoating, low-temperature reflowing and direct photodefinition. Examples are multimode photodefined passive polymeric waveguides for optical interconnect applications; photodefined monomode polymeric waveguides loaded with rare-earth doped nanoparticles for planar waveguide amplifiers and with non-linear chromophores for electro-optic modulators. We will show that polymer waveguide technology allows vertical stacking of electro-optic microringresonators with their port waveguides to realize high-speed modulators. By reflowing the reactive-ion-etched microring we could reduce the scattering by wall roughness considerably. Thermo-optic polymeric microringresonators combine the high thermo-optic coefficient and low thermal conductivity of polymers with the small size of the microring. It will be shown that this yields a broad wavelength tuning range at low power dissipation.