S. Pachnicke, J. Zhu, M. Lawin, A. Wonfor, M. Eiselt, R. V. Penty, R. Cush, R. Turner, P. Firth, M. J. Wale, I. H. White, J.-P. Elbers

First Demonstration of a Full C-Band Tunable WDM-PON System with Novel High-Temperature DS-DBR Lasers

© 2014 ADVA Optical Networking. All rights reserved.2

Outline

• Motivation

• Experimental Setup of Tunable WDM-PON

• Results• Automatic Wavelength Tuning• 1.25 Gb/s Transmission• 10.3 Gb/s Transmission

• Conclusion

© 2014 ADVA Optical Networking. All rights reserved.3

Motivation

Low-cost components are essential for tunable laser based WDM-PON

Requirements for customer premises equipment:

• Reduce tunable laser componentry• No thermo-electric cooler (TEC)

• No wavelength locker

• Network-based wavelength control with single wave locker for all ONUs located at central office (OLT)

• Avoid calibration of each laser• Generic tuning algorithm, laser currents adapted based on current wavelength tuning feedback

OLT

Tx

...1

RN

L C

N

AW

G

Rx

...1

N

AW

G

AW

G

L-Band 97.15 GHz

C-Band 100 GHzONU N

Rx

ONU 1

Rx

T-LD

T-LD

C L

C L

ITU-T698.3

© 2014 ADVA Optical Networking. All rights reserved.4

Experimental Setup

• Multi-user setup; novel high-temperature DS-DBR laser as central channel; used laser was not equipped for modulation ( use of external MZM)

• Upstream data transmission with 1.25 Gb/s and 10.3 Gb/s; Downstream data transmission with 1.25 Gb/s

• Demonstration of pilot-tone based overhead channel and centralized wavelength locking both realized in embedded hardware

OLT: optical line terminal; RN: remote node; ONU: optical network unit; PT: pilot tone generator; FPGA: field programmable gate array; MZM: Mach-Zehnder modulator; PRBS: pseudo-random bit sequence data source

© 2014 ADVA Optical Networking. All rights reserved.5

Tuning with Central Wave Locker

• AM tone powers are extracted by FFT on the received optical signal; multiple channels can be measured with a single etalon

• Wavelength error is calculated by comparing the etalon output power with the reference AM tone power

• Received power and wavelength error are communicated to ONU via tone channel

ONUOLT

iTLA

RN

AW

G

FPGA ECC Detection

DBR

Heater

MZM

AM Tone

µC

WaveLocker

FPGA: Data & ECC Generation

RXFPGA: FFT &Feedback Gen.

L C C

L

Etalon

© 2014 ADVA Optical Networking. All rights reserved.6

Wavelength Tuning Results

• After 20 s the right frequency slot has been identified

• Long-term frequency stability within ±10 GHz (limited by DAC resolution driving laser currents)

• Laser case temperature can vary between 70°C-90°C without any mode-jumps;operation with heater envisioned (here results are shown for 70°C)

0 10 20 30 40 50 60 70 80 90 100194.40

194.45

194.50

194.55

194.60

194.65

194.70

194.75

194.80

194.85

194.90

Time [s]

Fre

qu

ency

[T

Hz]

0 1000 2000 3000 4000 5000 6000 7000194.70

194.75

194.80

194.85

194.90

Time [s]

Fre

qu

en

cy [T

Hz]

Phase 1(Power Feedback)

Phase 2(Wavelength & Power Feedback)

© 2014 ADVA Optical Networking. All rights reserved.7

1.25 Gb/s Transmission Results

• Up to 80 km reach data transmitted error-free

• EDFA used at OLT only for 80 km reach (gain 20 dB)

approx. 2 dB penalty due to ASE noise

© 2014 ADVA Optical Networking. All rights reserved.8

10.3 Gb/s Transmission Results

• An EDFA has been used at the OLT at all times (Pout 2 dBm)

• Up to 40 km reach error-free transmission (longer reach possible by using EDFA with higher gain)

© 2014 ADVA Optical Networking. All rights reserved.9

Summary & Conclusion

• First demonstration of ONU with high-temperature DS-DBR laser

• First demonstration of automatic tuning on turn-on and long-term frequency stability (all realized in embedded hardware)

• Centralized wavelength locking & communication between ONUs and OLT by pilot-tone based communication channels

• Operation of tunable laser without wavelength locker and without thermo-electric cooler

Proves feasibility of using low-cost uncooled tunable lasers in ONUs for up to 10 Gb/s transmission rates

spachnicke@advaoptical.com

Thank you!

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