Silicon Photonics
Design-for-test and calibration
Focus on testability analysis, ring-resonator-based calibration, and scalable strategies for making photonic circuits observable and tunable after fabrication.
Academics
Research, publications, and academic work.
Graduate research at the University of Utah spanning thermal modeling of integrated optoelectronics, silicon photonics, design-for-test, and calibration.
Research
Photonics, CAD, and test methodology
My doctoral work brought together access, calibration, and test synthesis for silicon photonics. My earlier master’s work focused on thermal abstraction for integrated optoelectronics.
EDA Methods
Photonic design automation
Applies CAD and synthesis thinking to photonic systems, building abstractions that reduce analysis cost while preserving engineering usefulness.
Robustness
Thermal and variation modeling
Studies how temperature gradients, surface roughness, and manufacturing shifts affect behavior in microring resonators and integrated optoelectronic layouts.
Verification
ATPG, DFT, and testability analysis
Brings verification-oriented rigor from digital systems into silicon photonics, emphasizing measurable structure, fault visibility, and calibration-aware architecture.
Engineering methods
Silicon photonic design-for-testCalibration-aware architecturesRing resonator analysisWavelength division multiplexingHypergraph partitioningThermal characterization abstractionManufacturing variation modelingVerification-oriented reasoning
From device behavior to engineering decisions
Device physics, test planning, and manufacturing constraints inform the same design process.
Research-to-system translation
Frames silicon photonics as an engineering program problem, linking device effects, layout abstractions, test planning, and calibration into a coherent technical story.
Cross-disciplinary coordination
Connects photonics, circuit design, CAD, and verification methods so optical systems can be evaluated with the discipline expected in high-consequence engineering environments.
Manufacturability-minded rigor
Prioritizes real-world concerns such as thermal sensitivity, fabrication variation, observability, and post-fabrication tuning instead of idealized lab-only assumptions.
Master’s research · 2016
Thermal Characterization Abstraction for Integrated Optoelectronics
M.S., Electrical and Computer Engineering · University of Utah. Thermal modeling of integrated electronic and photonic systems.
My master’s research examined how heat from nearby electronics changes integrated photonic-device behavior. The work connects physical layout and material properties to temperature-dependent optical response.
GDSII layout
Geometry and material layers
Thermal network
Layered resistance model
Temperature field
Numerical thermal solution
Optical response
Refractive index and phase
- Method
- A compact thermal resistance network represents the material layers. A layered 2.5D model uses an alternating-direction implicit finite-difference solver to compute temperatures, which are then related to ring-resonator refractive-index and phase changes.
- Contribution
- The related 2016 VLSI Design paper demonstrates this layout-based abstraction through simulation using the GDSII layout of a fabricated optical-logic chip and a simulated heat source. At publication, comparison with laboratory measurements was identified as follow-on work.
Publications
Selected publications and thesis work
Published work on silicon photonics test, calibration, variation analysis, and thermal abstraction.
2025
IEEE International Test Conference (ITC)
Silicon Photonic Test-Point Selection by Integrating Design Parameters with Hypergraph Partitioning
Lawrence Schlitt, Pratishtha Agnihotri, Priyank Kalla, and Steve Blair
Extends observability planning for silicon photonic circuits using structure-aware partitioning methods.
View publication2025
IEEE European Test Symposium (ETS)
Design-for-Test and Calibration for Silicon Photonics using Ring Resonators and Wavelength Division Multiplexing
Pratishtha Agnihotri, Lawrence Schlitt, Priyank Kalla, and Steve Blair
Combines testing and tuning strategy around ring resonators and WDM to manage post-fabrication variation.
View publication2023
IEEE Latin American Test Symposium (LATS)
Abstractions for Modeling the Effects of Wall Surface Roughness in Silicon Photonic Microring Resonators
Pratishtha Agnihotri, Lawrence Schlitt, Priyank Kalla, and Steve Blair
Examines how fabrication-induced roughness shifts resonator behavior and affects performance margins.
View publication2016
International Conference on VLSI Design
A Methodology for Thermal Characterization Abstraction of Integrated Opto-electronic Layouts
Lawrence M. Schlitt, Priyank Kalla, and Steve Blair
Introduces abstraction techniques for thermal-aware reasoning in hybrid opto-electronic layouts.
View publication2016
University of Utah thesis
Thermal Characterization Abstraction for Integrated Optoelectronics
Lawrence M. Schlitt
Graduate thesis focused on tractable thermal modeling for integrated optoelectronic systems.
View publicationAcademic projects
Research in practice
The engineering problems, methods, and outcomes behind these lines of academic work.
Silicon photonic test-point selection
Photonic circuits need observability strategies that respect both physical structure and performance behavior.
Approach: Integrated design parameters with hypergraph partitioning to identify useful test points in more complex circuit topologies.
Outcome: Creates a scalable path for DFT planning as photonic systems move beyond small custom layouts.
Calibration flow using ring resonators and WDM
Fabrication and environmental variation can move photonic devices outside their intended operating window.
Approach: Built a combined testing and calibration framework around ring resonators and wavelength-division multiplexing.
Outcome: Bridges research prototypes and deployment-minded tuning workflows by treating calibration as part of system architecture.
Thermal abstraction for integrated optoelectronics
Full coupled thermal and electromagnetic simulation is expensive for hybrid opto-electronic stacks.
Approach: Developed abstraction methods that estimate functional impact from thermal gradients without requiring exhaustive full-scale simulation.
Outcome: Supports earlier thermal-aware decisions in the design flow while preserving technical credibility.
Manufacturing variation modeling in microring resonators
Surface roughness and process variation influence resonator behavior, yield, and design margin.
Approach: Studied abstraction techniques for modeling roughness-induced behavior shifts in silicon photonic microring structures.
Outcome: Improves robustness planning by bringing fabrication realism closer to early design-stage analysis.