InP-based monolithically
     integrated 1310/1550nm
         diplexer/triplexer

               a              a         ...
2



Outline
   • Motivation
   • Aim
   • Seamless Photonics
   • Fabrication
   • Integrated Chip Overview
      – Wide ...
3



 Motivation

 Reduce cost of optics using integration and few
 fabrication steps:

• Already demand for high bandwidt...
4


Aim

  – Replace Bulk Optics and Hybrid Optics
  – DFB, PD and WDM-filter in one InP Chip
5



Seamless Photonics

  Electrical bias defines material properties instead of different materials

  No reflective i...
Integrated Chip Overview:

                                                        Facet free 1550 DFB



Single mode wave...
7



  Wide gain and accepted losses
 Typical DFB spectrum     Wide gain 1310/1550nm spectrum

                           ...
8



    Wide gain
•   Subbands at different energies
•   Different quantum well effective
    bandgaps (1310+1550nm)
•   ...
9



     Wide gain (simulated in inset)
• Gain shifted from nominal 1250-1600nm (inset) to
• 1400-1800nm due to low p-dop...
10



    WDM coupler (as cleaved, no AR)
•   8dB port separation expected for used zerogap coupler
•   10dB port separati...
11



Diplexer chip MMI-coupler simulation
• Detector requires both TE and TM coupling
• 10-30dB multiplexing (split) depe...
12



Simulated MMI coupler -40ºC to +80ºC: Temperature independent

              1310nm
18-22dB
from -40º               ...
13



    Minor effect of diplexing
•   Biased coupler power
•   Blue: 1580nm only
•   Red: 1580 and 1310nm (1mW each).
• ...
14



1310 and 1550nm DFB lasers share fabrication
         •   Same basic structure
         •   Same ridge etch depth
  ...
15



    Extracted DFB-laser data
      300um cavity, as cleaved, with 1550nm DFB grating, at 30mA




DFB laser paramete...
16



1310nm and 1550nm WGPD (no AR)
•   Including coupling losses from fiber to WGPD
•   Unbiased photo diodes
•   0.31 A...
17


1 Gbps eye-diagram

    1dBm 1532nm from cleaved fiber

    As cleaved chip facet (no AR coating)

    200ps RC co...
18


Pig-tail of P2P-diplexer (8 channel) package prototype



        Carrier                   8-Channel V-groove




  ...
19



 Summary

• All fundamental properties demonstrated
   –   WDM multiplexing
   –   1310nm and 1550nm WGPD
   –   155...
20



    Acknowledgement

•   Royal Institute of Technology, Kista, Sweden
•   University College Vestfold, Norway
•   CI...
21


                                                                            WDM coupler and AR vs -47dB optical cross...
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PhoXtal APOC 2008 Presentation 081029

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PhoXtal APOC 2008 Presentation 081029

  1. 1. InP-based monolithically integrated 1310/1550nm diplexer/triplexer a a a b C. Silfvenius , M. Swillo , J. Claesson , N. Akram a c,d a,c,d E. Forsberg , M. Chacinski and L. Thylén a) PhoXtal Communications AB, Kista, Sweden b) University College VestFold, Tønsberg, Norway c) Royal Institute of Technology (KTH), Kista, Sweden d) Kista Photonics Research Center (KPRC), Kista, Sweden APOC 2008, October 29, Paper 7135-65
  2. 2. 2 Outline • Motivation • Aim • Seamless Photonics • Fabrication • Integrated Chip Overview – Wide Gain Active Material – WDM Coupler – DFB Laser – Waveguide Photodiode • P2P and PON arrays • Summary
  3. 3. 3 Motivation Reduce cost of optics using integration and few fabrication steps: • Already demand for high bandwidth internet services • IPTV will drive bandwidth demand further • Acceptance of FTTH is the next broadband step • The cost of optics is still a large part of FTTH network cost and obstacle for mass deployment
  4. 4. 4 Aim – Replace Bulk Optics and Hybrid Optics – DFB, PD and WDM-filter in one InP Chip
  5. 5. 5 Seamless Photonics  Electrical bias defines material properties instead of different materials  No reflective interfaces  Low cost process (few process steps)  High yield due to simplified fabrication process  Absorbing material between devices reduce optical/electrical crosstalk  Reduces oxidation issue in Al-containing compounds p-cladding Grating SCH-MQW “Seamless Photonics” Laser Chip and integrated n-cladding access waveguide” p-cladding Grating SCH-MQW Typical Integrated Photonic Chip with Butt-Joint n-cladding between laser and access waveguide
  6. 6. Integrated Chip Overview: Facet free 1550 DFB Single mode waveguides Diplexer chip 1310 PD 1Gbps IR camera image of Access ports single mode WDM coupler
  7. 7. 7 Wide gain and accepted losses Typical DFB spectrum Wide gain 1310/1550nm spectrum >200nm wavelength separation reduces Cross Gain Modulation (XGM) and Four Wave Mixing (FWM) Acceptable power losses in Accepted power losses in wide gain integrated existing semiconductor lasers semiconductor lasers
  8. 8. 8 Wide gain • Subbands at different energies • Different quantum well effective bandgaps (1310+1550nm) • Control of carrier transport in MQW >200nm FWHM measured
  9. 9. 9 Wide gain (simulated in inset) • Gain shifted from nominal 1250-1600nm (inset) to • 1400-1800nm due to low p-doping (large figure) • Low p-doping results in self-heating and carrier leakage before inverting 1310nm QW
  10. 10. 10 WDM coupler (as cleaved, no AR) • 8dB port separation expected for used zerogap coupler • 10dB port separation measured at 1580nm (and 1310nm) • 30dB port separation theoretical limit • Δn = 3.2x10-5/mA
  11. 11. 11 Diplexer chip MMI-coupler simulation • Detector requires both TE and TM coupling • 10-30dB multiplexing (split) depending on coupler design 1550nm TE 1550nm TM 1310nm TE 1310nm TM
  12. 12. 12 Simulated MMI coupler -40ºC to +80ºC: Temperature independent 1310nm 18-22dB from -40º 1550nm 15-18dB to +80ºC from -40º <0.5dB ' to +80ºC insertion <2.5dB loss insertion loss Coupler extinction ratio and insertion loss
  13. 13. 13 Minor effect of diplexing • Biased coupler power • Blue: 1580nm only • Red: 1580 and 1310nm (1mW each). • Small effect on FP spectrum (small change in refractive index)
  14. 14. 14 1310 and 1550nm DFB lasers share fabrication • Same basic structure • Same ridge etch depth • Same grating layer • Same spacer layer • Different grating periods • Different waveguide widths
  15. 15. 15 Extracted DFB-laser data 300um cavity, as cleaved, with 1550nm DFB grating, at 30mA DFB laser parameter extraction using Laser Parameter Extractor [LAPAREX, Tokyo University]
  16. 16. 16 1310nm and 1550nm WGPD (no AR) • Including coupling losses from fiber to WGPD • Unbiased photo diodes • 0.31 A/W @ 1310nm (400uA at 1.3mW power in fiber) • 0.52 A/W @ 1550nm (450uA at 0.78mW power in fiber) • Limited by optical power sources
  17. 17. 17 1 Gbps eye-diagram  1dBm 1532nm from cleaved fiber  As cleaved chip facet (no AR coating)  200ps RC constant  Noise form coupling imperfection
  18. 18. 18 Pig-tail of P2P-diplexer (8 channel) package prototype Carrier 8-Channel V-groove 8-Channel diplexer chip 8-Channel fiber ribbon
  19. 19. 19 Summary • All fundamental properties demonstrated – WDM multiplexing – 1310nm and 1550nm WGPD – 1555nm DFB laser threshold – 1310nm and 1580nm diplexing in same waveguide • Low p-doping (undoped SCH+MQW) limited carrier inversion level at electrical bias in this batch • Device performance is in accordance with models. info@phoxtal.com
  20. 20. 20 Acknowledgement • Royal Institute of Technology, Kista, Sweden • University College Vestfold, Norway • CIP Technologies, Ipswich, UK • ACREO AB, Kista, Sweden • VINNOVA, Stockholm, Sweden, • Innovationsbron, Stockholm, Sweden
  21. 21. 21 WDM coupler and AR vs -47dB optical crosstalk (assuming -3dB loss for internal laser per pass in coupler to avoid unintentional lasing) Additional filter needed as function of AR-coating and WDM coupler performance Additional filter to reduce optical crosstalk to 47dB 35 30 30% AR 4% AR 1% AR 25 0.5% AR 0.1% AR 20 0.05% AR 15 10 5 0 0 5 10 15 20 25 30 WDM Coupler Multiplexing [dB] 10dB zero gap coupler (current batch): 30dB coupler 0.1% AR coating for -47dB crosstalk 20dB MMI coupler (typical coupler): (theoretical limit): or 4% AR and additional 17dB filter 1% AR coating for -47dB crosstalk 4% AR coating for -47dB crosstalk or 4% AR and additional 7dB filter no additional filter

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