A compact bi-wavelength polarization splitting grating coupler fabricated in a 220 nm SOI platform (original) (raw)

Grating coupler serving as polarization beam splitter in silicon-on-insulator platform

We present in this work a one-dimensional grating coupler that serves as polarization splitter to couple the light from a single-mode optical fiber to single-mode integrated silicon waveguides and separate both orthogonal polarization states at the same time. The reported structure has been fabricated using standard complementary metal-oxide-semiconductor technology process and exhibits good coupling efficiency around-4 dB for both polarizations and high extinction ratios around 30 dB near the telecommunication wavelength 1550 nm at both outputs. The simulation and measurement results show the coupling and polarization splitting effect in a wide wavelength range and are in good agreement.

CMOS-Compatible Polarization Splitting Grating Couplers With a Backside Metal Mirror

IEEE Photonics Technology Letters, 2000

We present a highly efficient 1-D grating structure that serves to couple light between standard optical fibers and single-mode waveguides in the silicon-on-insulator platform and to split both orthogonal polarization states. The efficiency of the fabricated coupler is enhanced by a backside metal mirror and reaches −2.4 dB for both polarizations at 1552 nm with an extinction ratio > 25 dB in a wide wavelength range. The efficiency can be theoretically improved to −1.1 dB when optimizing the number of periods and using a nonuniform grating.

A compact two-dimensional grating coupler used as a polarization splitter

IEEE Photonics Technology Letters, 2000

We demonstrate a novel polarization splitter based on a two-dimensional grating etched in a silicon-on-insulator waveguide. The device couples orthogonal modes from a single-mode optical fiber into identical modes of two planar ridge waveguides. The extinction ratio is better than 18 dB in the wavelength range of 1530-1560 nm and the coupling efficiency is approximately 20%.

Passive broadband silicon-on-insulator polarization splitter

Optics Letters, 2007

We present the implementation of a novel wavelength independent polarization splitter on a silicon-oninsulator platform. The waveguide splitter is based on a zero-order arrayed waveguide grating (AWG) configuration. The splitting function is realized by employing cladding stress-induced birefringence. The device demonstrated a TE to TM splitting ratio better than −15 dB over a 20 nm tuning range centered around = 1550 nm and better than −10 dB over our entire accessible wavelength range from = 1465 nm to 1580 nm. The highest splitting extinction ratio achieved was −20 dB. To our knowledge, this is the first reported passive broadband polarization splitter based on AWG.

Reducing polarization-dependent loss of silicon-on-insulator fiber to chip grating couplers

… Technology Letters, IEEE, 2010

For many telecommunication applications, low Polarization Dependent Loss (PDL) operation is mandatory. On the silicon-on-insulator photonic wire platform this can be achieved using polarization diversity configurations. However, as we show here, when using two dimensional grating couplers for near vertical fiber input and output, the low PDL bandwidth is limited. We propose and demonstrate the use of a π phase shifter in one of the arms of the polarization diversity circuit to effectively reduce PDL (0.15 dB PDL is shown) and increase the low PDL bandwidth.

Broad parameter optimization of polarization-diversity 2D grating couplers for silicon photonics

Optics Express, 2013

Polarization-diversity couplers, which are designed to couple the unknown polarization state of an optical fiber into the TE-polarized modes of integrated waveguides, are important for the development of practical all-optical circuits. We describe the use of a full 3D finite difference time domain (FDTD) calculation campaign to rigorously optimize the 2D photonic crystal grating that couples a single-mode telecom fiber to the silicon waveguides of a Silicon-on-Insulator (SOI) platform. With this approach we identify the unique optimum combination of etch-depth, holeradius, and grating-pitch of the photonic crystal array for best performance at 1550 nm. The mean (polarization-averaged) coupling efficiency of 48% (−3.2dB) exceeds reported efficiencies of analogous couplers, and has only a marginal dependence on the polarization state of the input fiber (48 ± 3%). In addition, 3D-FDTD calculations are used to characterize the propagation direction, mode-profile, and polarization of light coupled from the fiber into the SOI slab. Such information is crucial for component design and goes beyond previously available results from existing approximations and simulations of 2D-grating coupler performance. Calculations of photonic mode dispersion in the grating coupler, by means of guided-mode expansion, indicate that the coupling is due to an optically active resonant guided mode in the photonic crystal array. This points towards a fast optimization scheme that enhances both the performance and the physical interpretation of 3D-FDTD simulations.

CMOS compatible cost-efficient fabrication of SOI grating couplers

Microelectronic Engineering, 2009

A CMOS compatible process for the cost-efficient fabrication of SOI grating couplers is presented. Test devices have been fabricated and characterized in a fully automated measurement setup at telecom wavelength (1550 nm). Coupling efficiencies of À3.6 and À4.1 dB have been achieved for TE and TM polarization, respectively. The 3 dB bandwidth has been measured to be about 50 nm.