Ultrafast, alloptical regeneration functionalities inside a Kerrnonlinear platform

1
Ultrafast, all-optical regeneration
functionalities inside a Kerr-nonlinear platform

• G. Priem, P. Vandersteegen, P. Bienstman, G.
  Morthier and R. Baets

2
Outline

• Introduction why NL optics
• All-optical NL platform
• Regenerator optimization
• Example
• Conclusions

3
Electronics vs optics interconnections

• From the physical point, optics has many
  advantages for device interconnections
• low loss and pulse distortion
• low crosstalk
• good impedance matching
• wavelength-division multiplexing (WDM)
• ...
• ? easy transport of gt1 Tb/s

4
Electronics vs optics data processing

• But what about the data processing?
• typically by means of O-E-O conversion
• high-speed processing (gt 40 GHz) difficult
• Solution ALL-OPTICAL signal processing
• Challenge ultrafast nonlinear effects (Kerr
  effect ...) are also very weak
• CONFINEMENT

• HC material systems wires
• resonant enhancement

5
Idea of resonator enhancement
The electric field (and Kerr effect) is enhanced
inside a resonator due to mirror
operation. Result asymmetric shift of resonance
wavelength Drawback strong mirror small
bandwidth
6
All-optical data processing

• Basic functionalities
• Phase shifting
• Limiting
• Switching
• Bistability (memory)
• POWER REQUIREMENTS?
• standard semiconductor (AlGaAs), 40 GHz ?
  1-5 pJ (ideal case)

Every all-optical function is theoretically
possible.
7
Non-ideal situation

• Reality will require higher powers
• Loss
• Noise, crosstalk

Fabrication optimization...
Regeneration (OA already present for NL
operation!!)
linear backplane (e.g. routing)
8
Imbedded reshaping

• Reshaping function is possible with
  Kerr-nonlinear
• resonator structures.
• Just an additional function behind OA

Pout (a.u.)
Pin (a.u.)
Pump OUT
pump IN
data OUT1
Resh
OA
data IN
data OUT2
NL
9
Theoretical example
pump OUT

• Consider a 40 Gb/s pump signal with
• Input Pav 0.1 mW
• Ext ratio P1/P0 2
• OA ? Pav 200 mW (Eav 5 pJ)
• Additional loss so output again Pav 0.1 mW
• Added noise in the system estimated at 0.007 mW
  (rms) at the output

pump IN
Resh
OA
NL
10
Theoretical example

• For reusing the pump signal, a BER of 10-12
• would be required
• Additional regenerationwith gt2 ?m radius ring
  resonator (AlGaAs)
• Optimization by means of bandwidth, wavelength
  offset ... with analytical model

pump OUT
pump IN
Resh
OA
NL
11
Minimum requirements

• Optimum design (in terms of power requirement)
• bandwidth 83 GHz
• wavelength offset 0.51?bandwidth
• required energy 3pJ lt 5pJ !!
• ? significant signal improvement with power that
  is ALREADY THERE

• very limited regeneration
• almost no peak loss
• significant improvement 10-6 ? 10-12

Pout (a.u.)
Pin (a.u.)
12
Eye diagrams
In absence of regeneration With regeneration
time (ps)
time (ps)
13
Potential

• Bit error rate as function of available Eav
• With the available 200mW (5pJ) BER ? 10-16

No regeneration
Log(BER)
Average energy (pJ)
14
Conclusions

• When thinking of ultrafast NL operations built
  into a platform...
• Theoretically possible
• Fabricating low-loss components will be a key
  aspect to limit power loss and allow consecutive
  operations (additional active areas might be
  required)
• Noise accumulation can be counteracted
• Large improvements with repetitive limited
  reshaping
• Required power is already available
• Compact, simple and extremely flexible