Chantal Blanchetiere

Arrayed waveguide gratings based on perfluorocyclobutane polymers for CWDM applications

Compact wavelength-division multiplexers based on arrayed waveguide grating structures have been designed and fabricated for short-haul communication network applications using low-loss perfluorocyclobutane-containing polymers. The devices exhibit high thermal stability and low on-chip losses. The average on-chip loss was <6 dB, including the fiber-to-chip coupling loss. The output uniformity across five channels was typically /spl plusmn/0.5 dB, and the thermal sensitivity of the central wavelength was 0.045nm//spl deg/C. Optimization of devices through material properties and fabrication process parameters is discussed.

Giant enhancement of the second harmonic generation efficiency in poled multilayered silica glass structures

Multilayered thin-film doped silica structures are experimentally demonstrated as an effective tool to enhance the second-order nonlinear properties induced in thermally poled glass devices. A 204-fold improvement is obtained in the second harmonic generated (SHG) in a poled structure with a 3 μm-thick multilayered stack consisting of sub- 100 nm-thick alternating germanium-doped and undoped silica layers compared to poled bulk silica glass. The induced nonlinearity is localized within the layered region, indicating that the multilayered design can be used to precisely control the thickness and the location of the nonlinearity. Such artificial nonlinear structures can be used to overcome the main limitations of existing poled glass devices, therefore opening the door to practical implementations of efficient active devices in silica glass.

Optical evanescent field waveguide Bragg grating pressure sensor

A ridge waveguide Bragg grating pressure or touch sensor is proposed. The sensor consists of an open-top ridge waveguide Bragg grating with an overlaid pressure sensing polydimethylsiloxane film. The effective index of the guided mode of the waveguide is changed by stress-induced variations in the film refractive index that are caused by increases in pressure normal to the waveguide. Pressure is then measured by monitoring the shift of the Bragg resonance resulting from the changes to the effective index. By using the smaller core size ridge waveguide, and a polymer with smaller Youngs modulus, the sensitivity of the sensor is enhanced. By utilizing the polarization dependence of the sensor response, a temperature-independent pressure sensor can be realized.

Fabrication of microchannel arrays in borophosphosilicate glass

Two-dimensional arrays of embedded channels with cross-sectional diameters of 1–3 μm were fabricated in silica-on-silicon thin film structures. The channel arrays were fabricated using void-forming borophosphosilcate glass (BPSG) deposited by plasma-enhanced chemical vapor deposition (PECVD) over templates patterned and etched using standard photolithographic methods and reactive ion etching. The sizeand shape of the channels could be controlled by adjusting the depth, width, and spacing of the template ridges, the dopant levels in the BPSG, and the annealing conditions. Optimization of the channel fabrication process through detailed investigation of the process variables is presented. Potential applications inphotonics, sensors, and microfluidics are discussed.

Property-tailorable PFCB-containing polymers for wavelength division devices

This paper demonstrates the application of property-tailorable perfluorocyclobutyl (PFCB) polymers to the fabrication of arrayed-waveguide grating (AWG) devices for use in wavelength division multiplexing (WDM) optical networks. This novel series of PFCB polymers exhibits low optical attenuation, high thermal stability, and tailorable refractive index, facilitating the design of high-performance photonic devices. The design, fabrication, and characterization of AWGs are reported in this paper. The fabricated devices show high thermal stability and low on-chip losses. Optimization of devices through the tailoring of material properties and fabrication process parameters is discussed. The successful fabrication of AWG highlights the potential of this material for other devices in photonic applications

Microchannel Arrays in Borophosphosilicate Glass for Photonic Device and Optical Sensor Applications

The fabrication of two-dimensional uniform arrays of microchannels in borophosphosilicate glass (BPSG) layers deposited by plasma-enhanced chemical vapor deposition (PECVD) is presented. The microchannels, with circular cross-sections of 2-3 μm diameter, are formed by depositing specific thicknesses of BPSG over periodic ridge/space templates etched into underlying silica layers using reactive ion etching (RIE). High temperature annealing results in reflow of the BPSG and the formation of uniform circular or cylindrical voids between the template ridges. Control of microchannel size and geometry through process variables is reported, and exploitation of the microfluidic and optical properties of microchannels and integrated waveguides for applications in optical sensing and photonic devices is demonstrated

Simultaneous corona poling of multiple glass layers for enhanced effective second-order optical nonlinearities

Silica-based thin-film multilayers are investigated as a means to enhance the effective second-order nonlinearity induced in silica glass structures by corona poling. Structures consisting of phosphorus-doped and undoped silica glass layers exhibit second harmonic generation (SHG) that is higher by an order of magnitude compared to the SHG in bulk silica glass poled under the same conditions. When the poled structure consists of two multilayered stacks separated in space, the stacks exhibit comparable poling-induced nonlinearities. This result suggests that the poling voltage is divided between the two stacks such that simultaneous poling of multiple regions within the sample is realized.

Temperature Insensitive Refractometer Using Core and Cladding Modes in Open-Top Ridge Waveguide

In order to overcome the well-known limitation of temperature instability in Bragg grating waveguide sensors, a temperature insensitive open-top ridge waveguide refractometer is developed by using a cladding mode resonance as a temperature reference. The relative shift of the core mode resonance to cladding mode resonance is used to measure the refractive index of substances under test. Specifically, the device fabricated here produces a relative resonance shift of 1 pm for every 5 times10-4 of measured index change, with a temperature sensitivity ~ 0.5 pm/degC.

Optimization of planar silica-on-silicon photonic devices through cladding material properties

The performance of silica-on-silicon planar waveguide devices is highly dependent on the properties of the layers comprising their structure. In this work we have investigated in some detail the properties of doped-silica layers formed by plasma enhanced chemical vapour deposition (PECVD). Parameters such as the refractive index, optical loss, stress and reflow characteristics of borophosphosilicate glass (BPSG) layers have been studied as a function of composition and processing conditions. Using the information gained, we have fabricated arrayed waveguide grating (AWG) demultiplexers and Bragg grating wavelength filter devices. Through careful adjustment of the properties of the top BPSG cladding layers, the performance of these devices, which are highly wavelength and polarization sensitive, can be easily controlled. Correlation of wavelength dependence, optical loss, and polarization dependence of different device designs, with the properties of the top BPSG cladding layer has allowed optimization of these devices and provides invaluable materials and process knowledge for the future use of silica-based layers in these and other photonic device applications.

Birefringence control for polymer optical waveguide devices

This paper reports planar waveguide fabrication using a novel fluorinated aromatic polyether bearing cross-linkable pentafluorostyene groups. This polymer exhibits high thermal stability and low optical loss, and the crosslinker used allows thermal processing at low temperatures (<200°C). The influences of the fabrication process and the substrate choices on the refractive index and birefringence of polymer layers have been investigated. Polymer ridge waveguide structures have been fabricated and characeterized, and device optimization through molecular design, fabrication process and substrate choice is discussed.