Component Library description - SiEPIC/SiEPIC_EBeam_PDK GitHub Wiki
Some of the components are decribed below, and others have descriptions in subfolders in the Documentation folder.
List of components:
- CML model: ebeam_wg_integral_1550
- Description: strip waveguide for operation around 1550 nm.
- Draw in KLayout using Waveguide Type = ROUND_PATH
- Support for Monte Carlo using wafer map
- Support for TE and TM polarization
- Waveguide width ranging from 0.4 µm to 3.5 µm
- Waveguide Height ranging from 210 to 230 nm
- Model uses interpolation for geometries not in the database
- CML model: ebeam_wg_strip_1550
- Description: Fully-etched strip waveguides. Typical width of 500 nm.
- Performance:
- SiEPIC & UBC researchers typically use 500 nm for TE and TM.
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- CML model: ebeam_wg_strip_1550 (same model as a regular waveguide, ignoring bends)
- Layout: spiral in EBeam PCells
- Description:
- Fully-etched strip waveguides. Width of 500 nm.
- TE – 7 dB/cm
- TM – 2.6 dB/cm
- September 2014
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- CML model: ebeam_wg_strip_1550 (same model as a regular waveguide, ignoring bends)
- Layout: waveguide_bump in EBeam PCells
- Description: Used to make a slightly longer waveguide within the same amount of space, e.g., 20 µm, plus 50 nm.
- CML model: ebeam_gc_te1550 and ebeam_gc_tm1550
- Description: Fully-etched fiber-waveguide grating couplers with sub-wavelength gratings showing high coupling efficiency as well as low back reflections forboth transverse electric (TE) and transverse magnetic (TM) modes., EBeam fabrication cost is reduced by ~2-3X when eliminating the shallow etch.
- Incremental Fabrication Cost: $0.02 each on Layer 1.
- Performance:,·,TE – 4.1 dB loss, 30.6 nm 1-dB bandwidth,·,TM – 3.7 dB loss, 47.5 nm 1-dB bandwidth
- Design tools & methodology:,·,2D & 3D FDTD(Lumerical Solutions),·,Scripted mask layout (Mentor Graphics Pyxis)
- Number of fabrication iterations (separate runs) to get to published results: 6
- Number of variations fabricated: 100+
- Reference: Yun Wang, et al., "Focusing sub-wavelength grating couplers with low back reflections for rapid prototyping of silicon photonic circuits", Optics Express, vol. 22, no. 17: OSA, pp. 20652-20662, 08/2014, http://dx.doi.org/10.1364/OE.22.020652
- Support for Monte Carlo using wafer map
- Support for TE and TM polarization
- Model uses S-Parameters generated for 9 variations.
 Fig.1 - SEM of op view of the sub-wavelength grating coupler. |
 Fig.2 - SEM of side view of the sub-wavelength grating coupler. |
 Fig.3 - Measured spectra of 11 identical sub-wavelength grating couplers. |
| Coupler type | Publication | Details |
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| Uniform | Yun Wang, et al., “Focusing sub-wavelength grating couplers with low back reflections for rapid prototyping of silicon photonic circuits”, Optics Express, 08/2014 |
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| Apodized | Yun Wang, et al., “Apodized focusing fully etched sub-wavelength grating couplers”. Photonics Journal, 2015 |
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| Broadband | Yun Wang, et al., “Design of Broadband Sub-Wavelength Grating Couplers with Low Back Reflection”, Optics Letters, 9/2015 |
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The Y-Branch is useful as a 1x2 splitter or a 2x1 combiner.
- Component: ebeam_y_1550
- Description: 50/50% splitter. Useful for splitting light, Mach-Zehner Interferometers, etc. The layout parameters for the device were taken from the journal paper below, and implemented in EBeam lithography.
- Performance: Excess loss <0.3 dB.
- Design tools & methodology: FDTD (Lumerical FDTD Solutions)
- Reference: Y Zhang, et al., “A compact and low loss Y-junction for submicron silicon waveguide”, Opt. Express, 21/1, pp. 1310-1316 (2013) http://dx.doi.org/10.1364/OE.21.001310
- Component: ebeam_dream_splitter_1x2_te1550, Library: EBeam-Dream
- Description: a 1x2 splitter or 2x1 combiner. Useful for splitting light, Mach-Zehner Interferometers, etc.
- Performance: Excess loss <0.1 dB.
- Compact Model: implemented in Lumerical INTERCONNECT, ebeam_dream.cml (installation instructions)
- Provided as an open-source "black box" component with a simulation compact model. A separate license is required for fabrication. A license for educational use within the edX Phot1x course is provided at no cost.
- by: Dream Photonics Inc., for more information: [email protected]
- CML model: ebeam_bdc_te1550 and ebeam_bdc_tm1550
- Description: 50/50% broadband directional 3-dB couplers. Two 3-dB couplers can be used to make an unbalanced Mach-Zehnder Interferometer (MZI), showing a large extinction ratio. The advantage of this device compared to the Y-Branch is that it has 2x2 ports, thus the MZI has two outputs; compared to the directional coupler, it is less wavelength sensitive.
- Performance:
- TE polarization operation
- CML model: ebeam_adiabatic_te1550 and ebeam_adiabatic_tm1550
- Description: 50/50% 2×2 broadband adiabatic 3-dB couplers/splitters. Two 3-dB couplers can be used to make an unbalanced Mach-Zehnder Interferometer (MZI), showing a large extinction ratio. The advantage of this device compared to the Y-Branch is that it has 2x2 ports, thus the MZI has two outputs; compared to the directional coupler, it is less wavelength sensitive.
- Performance:
- TE or TM polarization operation
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- CML model: ebeam_bragg_te1550
- Description: Uniform waveguide Bragg gratings, 1st order, TE polarization. This design provides a simple method of varying the grating strength (kappa) by changing the corrugation width (0 to 150 nm) and/or grating misalignment. The gratings can be either rectangular or sinusoidal (sinusoidal have more predictable performance).
- Grating misalignment:
- Kappa ranging from ~0 to 140,000 m-1, for a fixed ∆W = 50 nm, with misalignment technique
- Measured with oxide cladding.
- Design tools & methodology:
- Hand-drawn layout (kLayout)
- Post-fabrication modeling using Eigenmode (Lumerical MODE Solutions) 3D-FDTD (Lumerical FDTD Solutions)
- Number of fabrication iterations (separate runs) to get to published results: 1
- Number of variations fabricated: 10
- Reference: Xu Wang, et al., "Precise control of the coupling coefficient through destructive interference in silicon waveguide Bragg gratings", Optics Letters, vol. 39, issue 19, pp. 5519-5522, 10/2014 http://dx.doi.org/10.1364/OL.39.005519
- Measurement data from 2017/11 fabrication run by Applied Nanotools: https://github.com/lukasc-ubc/edX-Phot1x/tree/master/2017_Bragg_grating
- CML model: ebeam_disconnected_te1550 and ebeam_disconnected_tm1550
- Description: This component models what happens for a blunt waveguide ending (500 x 220 nm). Such a disconnect is identified as an error during layout verification, however, this effect is included in the Library for completeness to understand what happens when a port is left disconnected. This was modelled by 3D-FDTD, and data saved as S11 parameters. The device has one port.
This model is automatically used to simulate what happens when a component's pins are not terminated (see ebeam_terminator_te1550) or otherwise connected. INTERCONNECT assumes that there is no reflection from disconnected ports; the assumption is that there is a perfect matching between the component and whatever is outside (perfectly absorbing). This isn't physically correct. In order to account for the reflections from disconnected ports, the SiEPIC PDK in KLayout automatically adds this component to every disconnected port found in the layout.
- CML model: ebeam_terminator_te1550 and ebeam_terminator_tm1550
- Description: Unused ports on components should be terminated to avoid reflections (see ebeam_disconnected_te1550). This terminator is a nano-taper that spreads the light into the oxide. Even if a waveguide crosses near this taper end, the reflection is minimal (this is included in this model, 1 µm away, so the model is a worst-case reflection).
Other components, without an INTERCONNECT Compact model, and not embedded in the KLayout SiEPIC-EBeam-PDK.
These components can be found in the following folder: Dropbox
- Description: Uniform and apodized add-drop filters without an FSR, using Bragg-grating assisted contra-directional couplers. (De-)Multiplexers can be implemented by cascading multiple of such devices.
- Performance:
- Bandwidth ranging from sub-nanometer to 10+ nm depending on the coupler gap and grating design
- Sidelobe suppression: 10 to 20 dB using Gaussian apodization
- 4-channel CWDM (de-)multiplexer: flat-top responses, 1-dB bandwidth of 8 to 12 nm, crosstalk of -20 dB (Ref: CLEO 2013)
- Design tools & methodology:
- Eigenmode (Lumerical MODE Solutions)
- Scripted mask layout (Mentor Graphics Pyxis)
- Number of fabrication iterations (separate runs) to get to published results: 3
- Number of variations fabricated: 4
- References:
- W. Shi, el al., "Silicon CWDM Demultiplexers Using Contra-Directional Couplers," in CLEO: 2013, Optical Society of America, paper CTu3F.5. http://dx.doi.org/10.1364/CLEO_SI.2013.CTu3F.5
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- Description: bragg grating that produces selective wavelength filtering.
- Status: Beta; still under development, test devices have not been measured, use with discretion
- Reference paper: M. J. Strain et al, "Multi-wavelength filters in silicon using superposition sidewall Bragg grating devices," Optics Letters, vol. 39, (2), pp. 413, 2014.
- PCell Variable description:
- Number of bits (N): number of bits inside 'identity'
- Identity (binary size N): '1' is filtered wavelength, '0' is unfiltered
- start period: the defined period of the left most bit
- stop period: the defined period of the right most bit
- corrugations widths: the corrugation widths of each individual 'identity', separated by comma
- length (microns): length of the bragg device. Define 'length' instead of 'number of period', but 'number period' can be estimated as length/(stop period)
- sum format (1, 2, or 3):
- format 1: corrugation on both sides of the of waveguide
- format 2: corrugation with first half of identity on one side of the waveguide and the other half on the other side of waveguide
- format 3: currugation with even number identity on one side of the waveguide and the other half on the other side of waveguide
- Example:
- Description: Ring resonator. Useful for filters, sensors, etc. Also useful to extract fabrication non-uniformity
- Performance:
- Found that for EBeam process with existing wafer stock, the wavelength variation for resonators across the chip was +/- 3 nm. Grating coupler insertion loss varied by +/- 1.5 dB.
- Un-optimized ring: Line-width = 40 pm; Extinction Ratio = 6 dB
- Design tools & methodology:
- Eigenmode (Lumerical MODE Solutions)
- Scripted mask layout (Mentor Graphics Pyxis)
- Reference: L. Chrostowski, et al., "Impact of Fabrication Non-Uniformity on Chip-Scale Silicon Photonic Integrated Circuits", Optical Fiber Conference, 2014 http://dx.doi.org/10.1364/OFC.2014.Th2A.37
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- Description: Ring resonator with reduced sensitive to fabrication variations.
- Performance: 2.5X reduction in width sensitivity of resonance wavelength shift.
- Design tools & methodology: Eigenmode (Lumerical MODE Solutions)
- Reference: Jared C. Mikkelsen, et al., “Improving the dimensional tolerance of microrings with adiabatically widened bends” http://dx.doi.org/10.1364/CLEO_SI.2013.CM1F.5
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Description: We designed and fabricated a two-mode SOI ring resonator for MDM systems. By optimizing the device parameters, we have ensured that each mode is treated equally within the ring. Using adiabatic Bezier curves in the ring bends, our ring demonstrated a signal-to-crosstalk ratio above 18 dB for both modes at the through and drop ports. We conclude that the ring resonator has the potential for filtering and switching for MDM systems on SOI.
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Performance:
- 3D FDTD (Lumerical Solutions)
- 3D EME (FIMMWAVE)
- Scripted mask layout (Mentor Graphics Pyxis)
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Description: We report the fabrication and characterization of a silicon-based photonic integrated circuit consisting of a photonic crystal slot-cavity, waveguides, and grating couplers, designed as a robust, easy-to-use device for enhancing light-matter interactions at a precise location inside a fluidic medium, while minimizing fabrication complexity. Measured Q values in excess of 7500 for circuits immersed in hexane and operating near 1.5 μm are obtained, in good agreement with simulations. The detection limit for changes in solvent refractive index unit (RIU) for these structures, which have not been optimized, is 2.3×10−5 RIU.
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Design tools & methodology:
- 3D-FDTD (Lumerical FDTD Solutions)
- Reference: S. H. Mirsadeghi, et al., “Photonic crystal slot-microcavity circuit implemented in silicon-on-insulator: High Q operation in solvent without undercutting”, APL 102, 131115 (2013) http://dx.doi.org/10.1063/1.4799963
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- Description: Waveguide core is based on fully etched silicon blocks, repeated periodically, no upper cladding. Possibility of tailoring waveguide refractive index and optical properties by changing sub-wavelength gratings’ parameters.
- Performance: Bend loss (for 90º bend, TE polarization) is in the range 0.8-1.6 dB
- Design tools & methodology:
- MODE (Lumerical) + equivalent refractive index method
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Description: Waveguide core is based on fully etched silicon blocks, repeated periodically, no upper cladding. The SWG-based directional coupler has lower sensitivity to changes of central wavelength and to fabrication errors; furthermore, it introduces improvements in terms of wavelength flatness.
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Performance: Flat wavelength response on a wavelength span of more than 40 nm (TE and TM modes).
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Design tools & methodology:
- MODE (Lumerical) + equivalent refractive index method
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- Description: Converter to/from SWG-based waveguides and strip waveguides (TE and TM polarized light). Measurements have been performed with no upper cladding.
- Performance:
- Taper Loss in the range 0.4-0.8 dB
- Taper length is 30 um
- Design tools & methodology:
- MODE (Lumerical) + equivalent refractive index method
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- Description: SWG-based point coupled ring resonator.
- Performance: Q factor in the range of 1,000 to 6,000
- Design tools & methodology:
- MODE (Lumerical) + equivalent refractive index method
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