1. Performance Optimization of AOWCs
Task 1: All-Optical Wavelength Converter (AOWC)
Performance Optimization of AOWCs
Vikrant Lal, Milan L. Mašanović,
Daniel J. Blumenthal

2. Summary of Work
Modeling and Simulation of InP based AOWC to accurately estimate and design various performance metrics
Physics based modeling of optical processes in Quantum Well devices
Developed a Quantum Well Gain and Index model, and detailed rate equation based Dynamic SOA model
Issues
Need to improve noise modeling in the SOA
Need to include temperature dependent effects in a more detailed manner

3. Gain Model Compute Strained Quantum Well Band Structure
k.p theory based band computation
Gain curves vs. Carrier density are computed
Spontaneous emission factor and index change are also computed

4. Gain and Spontaneous Emission Spectra
QW gain vs. Wavelength at different Sheet
Carrier Densities N (1e12 cm-2)
Spontaneous emission at different Sheet
Carrier Densities N (1e12 cm-2)

5. Carrier Induced Index Change
Carrier induced Index change computed for modeling XPM
Free carrier Index change
Index change due to gain spectra change through Kramers-Kronig relation

6. Dynamic behavior of SOAs
N(z,t),g(z,t),n(z,t)
Psignal
Multi-section model
Device Carrier Density : N(z,t)
Device Gain : g(z,t)
Device Index : n(z,t)
ASE noise : PASE(t)
Each section is modeled based on the Coupled Rate equations
Psignal
Pnoise_f
Pnoise_b zi
Ni(t)
ni(t)
gi(t)
Pisignal(t)
Pi+1signal(t)
Pinoise_b(t)
Pi+1noise_f(t)
Pi+1noise_b(t)
Pinoise_f(t)

7. Simulating Device Operation
Input SOA
SGDBR
SOA1
SOA2
SGDBR Wavelength
Output
Power
(XGM)
Inverted
Phase
(XPM)
Non-Inverted

8. Device Operation (2.5Ghz NRZ)

9. Current Device Operation Limits
5Ghz NRZ

10. Increasing device operating speed
Signal power
Carrier Lifetime is approximately given by
The parameters that we can control to reduce lifetime are
Confinement factor
Signal Power
(mW)
Carrier Lifetime
(ps)

11. Effect of SGDBR power
Increasing Input CW power can help reduce Carrier Lifetime

12. Effect of Confinement factor
Increasing Modal Confinement factor has greater effect on Carrier lifetime

13. Increasing device operating speed
Signal power
Carrier Lifetime
Eye at 5Gbps with increased Power and Confinement

14. Future Design Improvements
Increased SGDBR Power
SOA at SGDBR output before going into MZI
Increased confinement and lower waveguide width
Centered Quantum Well, Buried Heterostructure design offers us these advantages
Quantum Well Intermixing offers an excellent platform for integration of such structures
1480nm Pumping to reduce carrier lifetime
On board 1480 source could be used to bring down carrier lifetime in the SOAs
Again, QWI could allow monolithic integration of 1480 and 1550nm sources

15. Future Work
Analyze device operation to understand how to better reduce carrier lifetime
Improve the noise model to accurately simulate noise characteristics of the wavelength conversion process
Run full dynamic simulations of the AOWC, that agree with experimental results and trends
Further simulate the effect of different design parameters on the operation to help improve device design.