Electro-Optic Modulators Workshop

Electro-Optic Modulators Workshop NUSOD 2013

Outline New feature highlights Electro-optic modulators Circuit level view Modulator categories Component simulation and parameter extraction Electro-optic modulator examples Travelling-wave PN junction Interleaved PN junction in microring Nanobeam PC with EO polymer Summary Questions and answers Dylan McGuire Senior R&D Scientist Lumerical Solutions, Inc. dmcguire.support@lumerical.com 2

Electro-Optic Modulators Workshop NEW FEATURE HIGHLIGHTS

EDA Integration with Mentor Graphics Lumerical s products can be integrated into EDA flow Layout photonic circuits in Mentor Graphics Pyxis Normally used for electrical circuit layout and simulation

EDA Integration with Mentor Graphics Export circuit from Mentor Graphics Pyxis to Lumerical s INTERCONNECT for photonic circuit simulation

Power (db) User Defined Material Models MODE Solutions 2.5D FDTD Propagator supports user defined materials Simulate linear and nonlinear dispersive, gain effects etc over large propagation distances (3) Raman 0 ( ) P( t) E( t) (3) Raman 2 Raman ( t) E (3) 0 2 j 2 ( t) 2 Raman Raman 2

3D Electrical Simulation with DEVICE 3 Automated, adaptive finite element mesh Enhanced integration with photonic simulation tools New analysis tools to simplify common tasks Enhanced solver physics and performance More information: http://docs.lumerical.com/en/device/ref_fdtd_new_features_new_features_for_version_3_0.html

DEVICE > 3D Simulation True 3D finite element solver Always supported 3D CAD Easy to extend current designs to 3D Simulate arbitrary geometries Improved solver performance with multithreading

DEVICE > Improved Analysis Tools New E-field and charge monitors Record carrier density (n,p), electrostatic potential, and field Volume/cross-section/line Integrated analysis Calculate total/net charge Easy export for electro-optic simulations No script required!

DEVICE > Improved Analysis Tools Total charge integration for junction capacitance Junction capacitance C = dq/dv

Electro-Optic Modulators Workshop ELECTRO-OPTIC MODULATORS

Multichannel Optical Transceiver

Circuit Model T. Baehr-Jones, et al., Ultralow drive voltage silicon traveling-wave modulator, Optics Express, 20, 12014 (2012).

Modulator Overview General principle Changing the carrier density (n, p) or electrostatic field perturbs the material index Charge modulation designs PN junction (depletion mode) PIN/PπN junction (charge injection) MOS capacitor/siscap Field modulation designs Electro-optic polymer slot and PC cavity Guided wave structures Travelling wave (Mach-Zehnder) Microring resonators Photonic crystals

PN Junction Reverse bias operation Junction width modulation Not limited by recombination lifetime Control capacitance with design Directly related to modulation efficiency Low C low loss: travelling wave High C high loss: microring

PIN/PπN Forward bias operation (charge injection) Carrier-lifetime limited Strong modulation effect at the expense of large currents Low-loss in OFF state Shorter modulation lengths V a

MOS Capacitor/SISCAP Operate in weak accumulation or inversion Loss depends on surface charge layer Accumulation: capacitance insensitive to frequency Travelling wave and microring structures

Electro-Optic Modulators > Simulation Workflow Electrical simulation I-V/C-V response Charge/electric field Material index From spatial charge/field data Optical simulation Effective index Loss

Electro-Optic Modulators > Simulation Workflow V a Electrical simulation I-V/C-V response Charge/electric field Material index From spatial charge/field data Optical simulation Effective index Loss

Electro-Optic Modulators > Simulation Workflow V a Electrical simulation I-V/C-V response Charge/electric field Material index From spatial charge/field data Optical simulation Effective index Loss

Electro-Optic Modulators > Modulation Response Phase change neff L neff V 2 0 0 2L Modulation EV, V 1 2 E 0 e 1 2 n 0 eff ( V ) L 1 e 2 n 0 eff ( V ) L 2 IL T E E 0 2 ER Parameter Value L 2mm V π 0.68V V π ER IL 24.4dB 0.4dB

Electro-Optic Modulators > Modulation Response Phase change neff L neff V 2 0 0 2L Modulation EV, V 1 2 E 0 e 1 2 n 0 eff ( V ) L 1 e 2 n 0 eff ( V ) L 2 IL T E 2 E 0 ER V π

Electro-Optic Modulators Workshop MACH-ZEHNDER MODULATOR

Depletion Mode PN Junction Travelling wave structure Electrical simulation: DEVICE, 2D cross-section Optical simulation: MODE Solutions, INTERCONNECT Reference: T. Baehr-Jones, et al., Ultralow drive voltage silicon traveling-wave modulator, Optics Express, 20, 12014 (2012).

Capacitance (ff/um) Depletion Mode PN Junction > C-V Simulation Peak doping concentrations from reference Adjusted implant profile to match C-V response Electron density (cm -3 s -1 ), log-scale 0.28 0.26 simulated measured [1] 0.24 0.22 0.2 0.18 0.16-1 0 1 2 3 4 Voltage (V)

Relative phase shift (rad.) Loss (db/cm) Depletion Mode PN Junction > Phase Response Model of Soref & Bennet used to convert carrier density in to local refractive index 22 18 n 0. 8 1.55m 8.810 n 8.5 10 p 18 18 1.55 m 8.510 n 6.010 p 2.5 6 2 1.5 1 0.5 0 measured (bot.) [1] -0.5 measured (top) [1] simulated -1-1 0 1 2 3 4 5 Voltage (V) 5.5 5 4.5 4 3.5 3-1 0 1 2 3 4 5 Voltage (V)

Depletion Mode PN Junction > Transmission Phase and loss data from component simulations Example project online: http://docs.lumerical.com/en/device/integrated_optics_travelling_wave_modulator.html

Electro-Optic Modulators Workshop MORE ELECTRO-OPTIC MODULATOR EXAMPLES

Interleaved PN Junction Microring structure Electrical simulation: DEVICE (3D) Optical simulation: FDTD Solutions (3D), INTERCONNECT Reference: J. C. Rosenberg, et al., "A 25 Gbps silicon microring modulator based on an interleaved junction," Optics Express, 20, 26411 (2012)

Interleaved PN Junction > C-V Response Peak doping concentrations from reference Adjusted implant profile to match C-V response Ref.: 0.65fF/um at 1V

Interleaved PN Junction > Phase Response Vπ-L calculated from phase referenced to 0V Ref.: 35dB/cm

Interleaved PN Junction > Circuit Model Phase and loss from component simulation Coupling coefficients and passive waveguide properties can be simulated with MODE Solutions Example project online: http://docs.lumerical.com/en/device/integrated_optics_interleaved_junction_microring.html

Nanobeam Photonic Crystal Waveguide-integrated 1D PC Electrical simulation: DEVICE (3D) Optical simulation: FDTD Solutions (3D) Reference: Biao Qi et al., "Analysis of Electrooptic Modulator With 1-D Slotted Photonic Crystal Nanobeam Cavity," IEEE Phot. Tech. Lett., 23, 992 (2011)

Nanobeam Photonic Crystal > Bandwidth Electrically, the structure is a semiconductorinsulator-semiconductor capacitor (SISCAP) Intrinsic bandwidth: f 3dB 1 2 2R slab C slot R slab R slab C slot

Nanobeam Photonic Crystal > Bandwidth Slab resistance calculated with "test" contact Cross-section gives conductance per unit length R = V/I

Nanobeam Photonic Crystal > Bandwidth Electric field monitors calculate net charge Electric field through the surface of the monitor C = dq/dv Device length: 14.8um f 3dB = 120GHz (ref.: 86GHz)

Nanobeam Photonic Crystal > Electric Field Electric field in EO polymer modifies the index Electric field monitor records and exports field profile as a function of voltage

Nanobeam Photonic Crystal > Resonance Shift Make field-dependent EO polymer 1 n 33 poly, 2 3 V, r n EV r Sweep over bias voltage High Q analysis: calculate resonance shift and Q factor of cavity

Nanobeam Photonic Crystal > V FWHM Q-factor and resonance frequency gives FWHM f Q R f c f Determine V required to shift f R by Δf Device length is 14.8um 0.43nm 0.8nm/V V.43nm FW HM 0 0.8nm/V 0.54V Compare to "Vπ-L": 0.8mV-cm (ref.: 0.28mV-cm) Example project online: http://docs.lumerical.com/en/device/integrated_optics_nanobeam_pc_eo_modulator.html

Electro-Optic Modulators Workshop SUMMARY

Summary Photonic integrated circuit simulation Optoelectronic component simulation requires a comprehensive suite of tools Component-level simulations provide insight into physical system behaviour DEVICE calculates the electrical response of semiconductor-based components: charge, electrostatics FDTD and MODE Solutions calculate the optical response for systems with complex, electrically-driven materials Component characterization can be used to develop portable, reuseable circuit models in INTERCONNECT Efficiently simulate large, complex optical circuits Lumerical's optoelectronic design tools are designed for accurate and efficient simulation and analysis

Summary More Information A copy of the presentation and project files will be available on our website http://www.lumerical.com/support/courses/lumerical_nusod2013.html Connect with us on LinkedIn Access insightful information on our products, services and upcoming webinars Lumerical Solutions, Inc.

Summary Contact our product experts Dr. James Pond FDTD Solutions jpond.support@lumerical.com Dylan McGuire DEVICE dmcguire.support@lumerical.com Amy Liu MODE Solutions aliu.support@lumerical.com Dr. Jackson Klein INTERCONNECT jklein.support@lumerical.com Sales inquiries: sales@lumerical.com Sales representatives: www.lumerical.com/company/representatives.html Free, 30 day trials at www.lumerical.com Connect with us on LinkedIn