Close to 100 Gb/s Discrete Multitone Transmission over 100m of Multimode Fibre Using a Single Transverse Mode 850nm VCSEL

Transcription

1 1 Proceedings SPIE 9766, (2015) Close to 100 Gb/s Discrete Multitone Transmission over 100m of Multimode Fibre Using a Single Transverse Mode 850nm VCSEL Wu Bo, Zhou Xian, Ma Yanan, Luo Jun, Zhong Kangping, Qiu Shaofeng, Feng Zhiyong, Luo Yazhi, Lu Chao Mikel Agustin, Nikolay Ledentsov Jr., Joerg Kropp, Vitaly Shchukin, Nikolay N. Ledentsov Iain Eddie

2 Outline 2 Motivation for single mode VCSEL Design and fabrication of single mode VCSELs Discrete Multi-Tone transmission (DMT) with multimode and single mode VCSELs over multimode fiber Perspectives for further improvements

3 High Speed VCSELs 3 Targets: High speed Temperature robust Reliable Single mode: - low chromatic dispersion - long distance - no mode partition noise - low RIN suitable for multilevel Conflicting design issues: Small aperture: low power, high resistance, low yield, single mode Large aperture: high power, reliable, 50 W, multimode Multiple oxide apertures: low capacitance, reliability issues, multimode Single aperture: high reliability, high capacitance, low speed

4 4 Bit Error Rate after DFE 1E-01 1E-02 1E-03 1E-04 1E-05 1E-06 1E-07 1E-08 1E-09 1E-10 1E-11 1E-12 1E-13 FEC 54 Gb/s VIS_SM_1km OM4 VIS_SM_BTB 1E Received Optical Power (dbm) Next generation VCSEL links 54Gb/s NRZ OOK over 1 km of multimode fiber (OFC 2016) 54Gb/s NRZ OOK over 2.2 km of multimode fiber (Electronics Letters, 2016) 80Gb/s PAM4 20GBaud 25GBaud 30GBaud 40Gbaud

5 850 nm VCSEL: Accelerated Ageing 5 Accelerated aging of 28 Gb s nm vertical-cavity surface-emitting laser with multiple thick oxide apertures JR Kropp et al Semiconductor Science and Technology 30 (4), (2015) Wafer level tests: 600 chips. 7 readouts per measurement Task: Keep similar epidesign and aperture size, extend the bandwidth, reach single mode operation No preemphasis/equalization

6 3D Modeling: Cross section 6 Fundamental Air Excited The 3D simulations of electromagnetic field Model: Finite element software package based on full vector Maxwell s equations DBR oxide Rotationally symmetric Thick oxide apertures Software: VIS VCSEL Software + JCM Wave + Matlab DBR Fundamental mode: lower leakage loss Higher order modes: higher leakage loss Direct visualization of the inplane leakage of high-order transverse modes in verticalcavity surface-emitting lasers mediated by oxide-aperture engineering Paper

7 Experiment: Near and far field 7 Leaky VCSEL: Appearance of a high order mode is accompanied by the evolution of specific narow lobes at high tilt angles (35 o )

8 DMT experiment: VCSEL properties 8 Single mode VCSEL 30dB SMSR Drive current optimal for DMT: 3mA F -3dB ~16 GHz (less than 20GHz at 4-5mA) Further drastic improvement in lifetime id possible for low current operation!!! Compared to MM VCSEL

9 Experimental Setup 9 Experimental setup of DMT based VCSEL-MMF link The constellation diagram 255 data subcarriers

10 Subcarrier Bit loading 10 (a) (b) MM-VCSEL -5 dbm SM-VCSEL SM VCSEL: as the distance increases, the bit rate goes down from 84Gbps at 0m to 82Gbps-100m, 75Gbps-200m and 72Gbps-300m. MM-VCSEL based MMF system, 68Gbps-0m to 63Gbps-100m, 54Gbps- 200m and 42Gbps-300m

11 Transmission capacity reduction 11 m m SM VCSEL shows a much higher robustness to data trasnmission distance over MMF at large distances

12 Transmission capacity 12 At 0dBm SM VCSEL allows >100 m MMF at 100 Gb/s Maximum MMF distance at 100 Gb/s: 300 m MM VCSEL is much less efficient for DMT

13 Next Generation Single Mode VCSELs 13 IR imaging of the oxide aperture Targets: High speed epi-design, mask layout and processing design as in MM VCSEL Standard aperture size ~4-6 µm

14 Next generation single mode VCSEL 14 EL Intebnsity (arb.un.) 1E-3 1E-4 1E-5 1E-6 1E-7 SMSR=36dB ma 3 ma RT SMSR=33dB Power (mw) RT CW 1E Wavelength (nm) Drive Current (ma) Amplitude (db) 0-5 RT f -3dB 3mA 4mA 26 GHz - 3dB modulation bandwidth ~25 26 GHz at 3-4 ma Keeping standard reliable technology Modulation Frequency (GHz)

15 Conclusion 15 Single mode VCSEL has a high potential at >100 Gb/s DMT over long distances of multimode fiber >300 m Novel concepts for SM VCSEL (short lifetime for high order modes) SM VCSEL provides an advantage over MM VCSEL in DMT modulation already at Butt-to-Butt configuration SM VCSEL bandwidth of f -3dB ~16GHz is enough for >100Gb/s and MM VCSEL suffers from a strong capacity reduction with increased distance of MMF. Further significant improvements in data transmission over MMF can be expected with new generations of SM VCSELs. Thank You! Visit us at Booth Hall D

16 16 Thank You! Visit us at Booth Hall D This project has received funding from the European Union s Horizon 2020 research and innovation programme under grant agreement No