A compact all-silicon temperature insensitive filter for WDM and bio-sensing applications

We propose a compact, temperature-insensitive, and all-silicon Mach-Zehnder interferometer filter that uses the polarization-rotating asymmetrical directional couplers. Temperature sensitivity of the filter is <8 pm/K for a wavelength range of 30 nm. The device achieves a reduced footprint by making use of different polarizations, which is made possible by the asymmetric directional couplers that act both as a splitter/combiner and as a polarization rotator. Simulation of the device shows that it can also be useful for gas sensing and bio-sensing applications with three times larger response to cladding changes while keeping a thermally robust behavior

Fabrication tolerant silicon MZI filter

A compact fabrication tolerant MZI filter is demonstrated. The measured device shows a 20-fold improved tolerance to systematic waveguide linewidth variations, with a wavelength shift of less than 60 pm/mm linewidth change

Maximizing fabrication and thermal tolerances of all-silicon FIR wavelength filters

We propose a method to make silicon optical finite impulse response filters tolerant to fabrication (waveguide geometry) and ambient thermal variations. We experimentally demonstrate a Mach-Zehnder interferometer filter with fabrication and thermal tolerance, both separately and together. The fabrication-tolerant device measurements show a 20-fold improved tolerance to systematic waveguide linewidth variations with a wavelength shift of <60 pm/nm linewidth change. The fabrication-and thermal-tolerant device is possible using orthogonal polarizations in the two arms. The fabricated device shows a shift of less than +/- 65 pm/nm and a thermal drift smaller than +/- 15 pm/K over a wavelength range of 40 nm. Simulations show that this concept can be extended to multichannel filters

Coarse wavelength division multiplexer on silicon-on-insulator for 100 GbE

A four-channel cascaded MZl based de-multiplexer at O-band with coarse channel spacing of 20 nm and band flatness of 13 nm is demonstrated on silicon-on-insulator. The device shows a mean crosstalk and insertion loss below -16 dB and 2.5 dB

Compact thermally tunable silicon racetrack modulators based on an asymmetric waveguide

A compact wavelength-tunable 10-Gb/s silicon racetrack modulator with integrated thermo-optic heater is demonstrated by using a waveguide with an asymmetric cross section, combining the compact footprint of microdisk modulators with the design simplicity of regular racetrack or ring modulators. The outer perimeter of the asymmetric racetrack modulator is fully etched to maximize optical confinement, and the inner waveguide edge is shallowly etched to maintain an electrically conductive path to the embedded p-n diode and to control the propagation of the asymmetric optical mode and its coupling to the bus waveguide. The resistive heating elements based on highly doped Si strips are implemented at the outer edge of the modulator for thermo-optic control. The asymmetric modulators can be fabricated along with Si wire waveguides and shallowly etched fiber-grating couplers using a simple process flow involving just two Si-patterning steps. Devices with a bending radius of 10 mu m and a novel "T"-shaped p-n diode layout have been fabricated, and exhibit electro-optic modulation and heater efficiencies of 28 pm/V and 42 pm/mW, respectively. At 10 Gb/s, a stable extinction ratio of 10 dB is demonstrated from a 2V(pp) drive swing, which can be maintained over a wavelength range of 4.6 nm by thermally tuning the modulator. This is equivalent with a temperature variation of about 62 degrees C

Experimental extraction of effective refractive index and thermo-optic coefficients of silicon-on-insulator waveguides using interferometers

We propose and demonstrate an accurate method of measuring the effective refractive index and thermo-optic coefficient of silicon-on-insulator waveguides in the entire C-band using three Mach-Zehnder interferometers. The method allows for accurate extraction of the wavelength dispersion and takes into account fabrication variability. Wafer scale measurements are performed and the effective refractive index variations are presented for three different waveguide widths: 450, 600, and 800 nm, for the TE polarization. The presented method is generic and can be applied to other waveguide geometries and material systems and for different wavelengths and polarizations