Planar Concave Grating Research Articles

Germanium-on-silicon planar concave grating wavelength (de)multiplexers in the mid-infrared

Mid-infrared wavelength (de)multiplexers based on planar concave gratings (PCGs) fabricated on a germanium-on-silicon waveguide platform are presented. PCGs with two different types of gratings (flat facet and distributed bragg reflectors) are analyzed for both transverse electric (TE) and transverse magnetic (TM) polarizations. The insertion loss and cross talk for flat facet PCGs are found to be −7.6/−6.4 dB and 27/21 dB for TE/TM polarization. For distributed bragg reflector PCGs the insertion loss and cross talk are found to be −4.9/−4.2 dB and 22/23 dB for TE/TM polarization.

Focusing and demultiplexing of an in-plane hybrid plasmonic mode based on the planar concave grating

In this paper we present the focusing and demultiplexing of an in-plane propagating hybrid plasmonic mode based on the planar concave grating structure. The grating system is designed based on the Rowland mounting, where the Rowland circle provides the focusing ability while the grating itself provides the dispersion. About 30nm's resolution is achieved in the current design and can be further improved by adjusting the grating parameters. The in-plane design makes the device free of the surface plasmon polariton (SPP) coupling issues and is favorable for planar integrated circuits (PICs). Furthermore, the grating system with linear dispersion offers convenience in designing wavelength division multiplexing (WDM) elements.

Silicon-on-insulator spectrometers with integrated GaInAsSb photodiodes for wide-band spectroscopy from 1510 to 2300 nm

We present a silicon-on-insulator (SOI) based spectrometer platform for a wide operational wavelength range. Both planar concave grating (PCG, also known as echelle grating) and arrayed waveguide grating (AWG) spectrometer designs are explored for operation in the short-wave infrared. In addition, a total of four planar concave gratings are designed to cover parts of the wavelength range from 1510 to 2300 nm. These passive wavelength demultiplexers are combined with GaInAsSb photodiodes. These photodiodes are heterogeneously integrated on SOI with benzocyclobutene (DVS-BCB) as an adhesive bonding layer. The uniformity of the photodiode characteristics and high processing yield, indicate a robust fabrication process. We demonstrate good performance of the miniature spectrometers over all operational wavelengths which paves the way to on-chip absorption spectroscopy in this wavelength range.

Silicon-on-Insulator CWDM Power Monitor/Receiver With Integrated Thin-Film InGaAs Photodetectors

In this letter, we demonstrate a compact and cost-effective four-channel demultiplexer with integrated photodetectors for application in coarse wavelength-division-multiplexing systems. The device consists of a silicon-on-insulator planar concave grating (PCG) demultiplexer and heterogeneously integrated InAlAs-InGaAs metal-semiconductor-metal photodetectors, and has a footprint of only 0.1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The PCG and integrated photodetectors have a responsivity of 0.6 A/W for TE-polarized light. The integrated device has an optical crosstalk of -25 dB.

Planar Concave Grating Demultiplexer Fabricated on a Nanophotonic Silicon-on-Insulator Platform

We show that a nanophotonic silicon-on-insulator (SOI) platform offers many advantages for the implementation of planar concave grating (PCG) demultiplexers, as compared with other material systems. We present for the first time the design and measurement results of a PCG demultiplexer fabricated on a nanophotonic SOI platform using standard wafer scale CMOS processes including deep-UV lithography. Our PCG device has four wavelength channels with a channel spacing of 20 nm and a record-small footprint of 280times150 mum. The on-chip loss is 7.5 dB, and the crosstalk is better than -30 dB