We have designed and fabricated Mach-Zehnder interferometer thermooptic switches using a wafer-bonded thin-silicon-on-insulator materials system. The thermally switched devices use single-mode strip waveguides with dimensions 0.26/spl times/0.6 /spl mu/m/sup 2/, operating at a wavelength of /spl lambda/=1.55 /spl mu/m. Useful device characteristics include a low switching power, 50 mW, and a fast rise time of <3.5 /spl mu/s. These results demonstrate the potential of this high-index-contrast materials system for the design of fast and low-power thermooptic switches and as an active element in photonic integrated circuits.

Fast and low-power thermooptic switch on thin silicon-on-insulator

Polymer thermo-optic-waveguide taps have a potential application as light routers for guided-wave optical interconnects involving cascaded fanouts. The taps can guide light from an optical bus bar and direct it into other devices in a switching/modulation network. Thermo-optic waveguide taps are designed and fabricated on silicon wafers using standard very large-scale integrated fabrication techniques. Coupling of light into an adjacent waveguide tap is observed to increase by 12.3% from 38.7% to 51.0% with the application of 34 mW of power.

Thermo-optically tuned cascaded polymer waveguide taps

Fluorinated polyimide waveguides with low polarization dependent loss (PDL) and thermooptic (TO) switches made from them were demonstrated. The waveguides showed loss of less than 0.3 dB/cm at the wavelength of 1.3 /spl mu/m and 0.6 dB/cm at 1.55 /spl mu/m for both TE and TM polarizations. The PDL's were less than 0.1 dB/cm. Extinction ratios of Y-branching-type TO switches fabricated from these waveguides were larger than 20 dB when over 160 mW of electric power was applied at 1.3 /spl mu/m, and over 150 mW at 1.55 /spl mu/m. The switching speed was faster than 8 ms.

Fluorinated polyimide waveguides with low polarization-dependent loss and their applications to thermooptic switches

A thermally activated variable attenuator for long-range (low-loss) surface plasmon-polariton (LRSPP) waves is discussed in this paper. The surface plasmon waveguide consists of a thin Au stripe on a thick layer of SiO2, which is covered by a thick layer of index-matched polymer. The structure is optically symmetric near room temperature, supporting an LRSPP. Increased attenuation of the mode occurs upon heating of the Au stripe via the passage of current therein. Heating substantially changes the refractive index of the polymer near the stripe, rendering the structure highly optically asymmetric and cutting off the mode. Thermal modeling results that link the injected current density to the refractive-index perturbation are presented and discussed. Experimental results validate the thermal modeling and demonstrate the operation of the device at a free-space optical wavelength near 1550 nm. The resistivity of the stripe is also measured as a function of the drive current, and the simultaneous use of the stripe as a thermal monitor is discussed and demonstrated

Thermally Activated Variable Attenuation of Long-Range Surface Plasmon-Polariton Waves

By exploiting the small bend radius achievable using high-index-contrast silicon photonic wire waveguides, we demonstrate a new low power thermo-optic switch arranged in a dense, double spiral geometry. Such a design permits the waveguide length to be extended for increased phase shift, without the need for increased heated volume. This provides an effective means to reduce the power consumption of thermo-optic switches, as well as a compact geometry desirable for the development of switch arrays. A low switching power of 6.5 mW was obtained for a spiral-path Mach-Zehnder interferometer device having a 10% - 90% rise time of 14 micros. The switching power is shown to be reduced by more than 5 times compared to a Mach-Zehnder interferometer employing a conventional straight waveguide geometry.

Compact and low power thermo-optic switch using folded silicon waveguides

A polymer waveguide thermooptic 2*2 switch with low electric power consumption is demonstrated. The switch consists of a Mach-Zehnder interferometer with Cr thin-film heaters. The waveguides are fabricated using acrylic polymers synthesized from deuterated methacrylate and deuterated fluoromethacrylate monomers. The total insertion loss of the switch is 0.6 dB at a wavelength of 1.3 mu m, including fiber coupling losses and waveguide losses. The switching power is as low as 4.8 mW, and the rise and fall times are both 9 ms. >

H. Onose

Papers

Polymer waveguide thermooptic switch with low electric power consumption at 1.3 mu m