Paper
12 February 2008 Demultiplexer with blazed waveguide sidewall grating and sub-wavelength grating structure
Przemek J. Bock, Pavel Cheben, Jens H. Schmid, Dan-Xia Xu, Siegfried Janz, Trevor J. Hall
Author Affiliations +
Abstract
We propose an original diffraction grating demultiplexer (spectrometer) device with a very small footprint, designed for the silicon-on-insulator waveguide platform. The wavelength dispersive properties are provided by a second-order diffraction grating lithographically defined and etched in the sidewall of a curved Si waveguide. The grating is blazed to maximize the -1st order diffraction efficiency. The diffracted light is coupled into the silicon slab waveguide via an impedance matching sub-wavelength grating (SWG) graded-index (GRIN) anti-reflective interface. The waveguide is curved in order to focus the light onto the Rowland circle, where different wavelengths are intercepted by different output waveguides. The phase errors were substantially reduced using an apodized design with a chirped grating pitch, which assures a constant effective index along the grating length. The simulated crosstalk is -30 dB. The device has 15 channels with a spacing of 25 nm, thus a broadband operational bandwidth of 375 nm. Its performance approaches the diffraction limit. The device layout size is 90 μm × 50 μm, which is the smallest footprint yet reported for a mux/dmux device of a similar performance.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Przemek J. Bock, Pavel Cheben, Jens H. Schmid, Dan-Xia Xu, Siegfried Janz, and Trevor J. Hall "Demultiplexer with blazed waveguide sidewall grating and sub-wavelength grating structure", Proc. SPIE 6896, Integrated Optics: Devices, Materials, and Technologies XII, 68960H (12 February 2008); https://doi.org/10.1117/12.763357
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KEYWORDS
Waveguides

Diffraction gratings

Demultiplexers

Silicon

Modulation

Diffraction

Phase shift keying

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