ISP part 3
- 1. AIM Academy Part 1: Context Electronic-Photonic Integration Confinement Part 2: Passive Devices Waveguides Off-Chip Couplers Wavelength Division Multiplexing Part 3: Active Devices Photodetectors Modulators Light Sources and Lasers Integrating Photonics
- 2. AIM Academy Active Photonics: Photodetectors Broadband, highly efficiency IR detector Bandwidth considerations Adaption to size of optical mode Low voltage operation Si processing, integrated into CMOS process flow Integration with ICs G. Dehlinger et al., IEEE Phot. Tech. Lett.,v.16(11), (2004). Active Photonics: Photodetectors
- 3. AIM Academy Photodetector Basics - Absorption 1.55 1.242.07 0.62 λ (μm) Physics of Semiconductor Devices, by S.M. Sze and K.K. Ng (Wiley-Interscience, 3rd edition, 2006) Photodetector Basics - Absorption
- 4. AIM Academy Ge Epitaxy on Si Si Ge Ge epitaxial growth on Si at 550C Si Ge Ge Epitaxy on Si
- 5. AIM Academy H.C. Luan, D.R. Lim, K.K. Lee, K.M. Chen, J.G. Sandland, K. Wada and L.C. Kimerling, APL, v.75(19), pp.2909-2911 (1999). L. Colace, G. Masini, G. Assanto, H.C. Luan, K. Wada and L.C. Kimerling, APL, v.76(10), pp.1231-1233 (2000). J. Liu, J. Michel, W. Giziewicz, D. Pan, K. Wada, D. D. Cannon, S. Jongthammanurak, D. T. Danielson, L. C. Kimerling, J. Chen, F. O. Ilday, F. X. Kartner, and J. Yasaitis, Appl. Phys. Lett. 87, 103501 (2005). Ge-on-Si Photodetector 2-step UHV-CVD + cyclic thermal annealing 780-900C anneal 10 TDD: 2.3107 cm-2 2.3106 cm-2 increases hole mobility Ge-on-Si Photodetector
- 6. AIM Academy Waveguide-integrated Photodetector Waveguide - Photodetector Integration Performance Gain 10 2 10 3 10 4 0 10 20 30 40 50 60 70 80 (Bandwidth)x(Quantumefficiency)(GHz) Detector Size (mm2 ) d=0.5μm 5mm20mm Q.E: 90% Discrete, free-space Photodetectors RC time limitTransit time limit RC time limit d=2.0μm J. Michel, J. F. Liu, L.C. Kimerling, , Nat. Photonics 4, 527 (2010) Waveguide - Photodetector Integration
- 7. AIM Academy 7 Ge-directly-on-Si Photodetector Waveguide Integration IMEC EPIXFAB Platform IME Singapore Platform A. Novak, Optics Express 21, 28387 (2013)
- 8. AIM Academy Monolithic germanium/silicon avalanche photodiodes Y. Kang, H.-D. Liu, M. Morse, M. J. Paniccia, M. Zadka, S. Litski, G. Sarid, A. Pauchard, Y.-H. Kuo, H.-W. Chen, W. S. Zaoui, J. E. Bowers, A. Beling, D. C. McIntosh, X. Zheng, J. C. Campbell, Nat. Photonics 3, 59 (2009) Measured 3-dB bandwidth versus gain of 30-mm-diameter germanium/silicon APDs at a wavelength of 1,300 nm. The coloured symbols are measured bandwidths from four devices. The blue line is the calculated bandwidth assuming carrier transit time and RC time constant are the limiting factors for the device bandwidth. The black line is a calculated result considering the avalanche build-up effect13 with keff ¼ 0.08. The corresponding gain–bandwidth product is 340 GHz, which fits the measured values. BW, bandwidth.
- 9. AIM Academy Active Photonics: Modulators Compact, integrated, Si-compatible Low power consumption J. Liu, S. Jongthammanurak, D. Pan, J. Michel and L.C. Kimerling Silicon Microphotonics Sandia Si ring Active Photonics: Modulators
- 10. AIM Academy Modulator Principles Physical Principles Thermo-optical Effect Change the refractive index of Si by heating. Plasma Dispersion Effect Change the refractive index of Si by carrier injection in a diode structure or carrier accumulation in a MOS structure. Electric Field Effect - Franz-Keldysh Effect in Bulk GeSi Change the absorption or refractive index of GeSi by electric field. - Quantum Confined Stark Effect in Ge/GeSi Quantum Wells Change the absorption or refractive index of Ge Q-wells by electric field. Basic Device Structures Mach-Zehnder Interferometers Interferes two beams of light with different phases. Phase shift achieved by changing the refractive index. Ring Modulators Change the resonance frequency of a ring by varying its refractive index, thereby controlling the coupling of light from an adjacent waveguide. Electro-absorption Modulators Light passes through an active material whose absorption can be changed by varying the applied electric field Plasmonic Modulators Modulator Principles
- 11. AIM Academy Mach Zehnder Modulator Phase delay in lower arm causes interference Large device size due to small effect Length 0.5-3mm Mach Zehnder Modulator
- 12. AIM Academy MOS-Enhanced Mach Zehnder Modulator FET design: rapid injection and extraction of free carriers Phase delay due to n from plasma dispersion Large device size due to small effect: MZ-arm length 1-3mm > 15 dB Mod. Depth @ 3 V Up to 30Gbps A. Liu, L. Liao, D. Rubin, H. Nguyen, B. Ciftcioglu, Y. Chetrit, N. Izhaky, and M. Paniccia, Optics Express 16, 660 (2007) MOS-Enhanced Mach Zehnder Modulator
- 13. AIM Academy Microring Modulators 1.5 Gbit/s using RZ pattern Power consumption of >50fJ/bit Less than 0.3V and µA current needed for complete modulation in DC In AC, 3.3Vpp and 1mA current were used Expected theoretical bandwidth limit >10Gb/s Diameter = 12μm Width = 450nm Gap = 200nm M. Lipson, “Switching light on a silicon chip,” Opt. Mat., v.27, pp.731-739 (2005). Q. Xu, B. Schmidt, S. Pradhan and M. Lipson, “Micrometre-scale silicon electro- optic modulator,” Nature, v.435, pp.325-327 (2005). P. Dong et al., “Low Vpp, ultralow-energy, compact, high-speed silicon electro- optic modulator”, Optics Express, Vol 17 No 25 (2009) Microring Modulators
- 14. AIM Academy Low Power Si Ring Modulators W.A. Zortman, M. R. Watts, D. C. Trotter, R. W. Young and A. L. Lentine, “Low-Power High-Speed Silicon Microdisk Modulators,“ OSA / CLEO/QELS 2010 CThJ4 Low Power Si Ring Modulators
- 15. AIM Academy Plasmonic Modulators Plasmonic mode concentrates optical field within nm thin film Optical absorption of thin film can be tuned by carrier injection Length of 3l Power consumption of <50fJ/bit expected Expected theoretical bandwidth limit >300Gb/s V.J. Sorger, N.D. Lanzillotti-Kimura,R.-M. Ma, X. Zhang” Ultra-compact silicon nanophotonic modulator with broadband response.” Nanophotonics 1, 17-22 (2012). Plasmonic Modulators
- 16. AIM Academy Electro Absorption Modulator Quantum Confined Stark Effect Weak EO effect in Si mm-scale MZ modulator, Q ring resonator Stark Effect: l100-400 mm, V1 V, Q=0 Observe QCSE: Ge/SiGe type I confinement and strong direct gap absorption comparable to III-Vs (t<ps, mod. rate >50GHz) Exciton peak 80 meV above Ge Ec - 36 meV strain shift - 56 meV quantum confinement Clear shift of exciton peak with 5 V: /6 @ l=1.46 mm Y.-H. Kuo, Y.K. Lee, Y. Ge, S. Ren, J.E. Roth, T.I. Kamins, D.A.B. Miller and J.S. Harris, "Strong quantum-confined Stark effect in germanium quantum-well structures on silicon," Nature, v.437, pp.1334-1336 (2005). Electro Absorption Modulator
- 17. AIM Academy Electro Absorption Modulator Franz-Keldysh Effect in GeSi Linear electro-optic effect n(E), (E) Ge-on-Si: comparable to InP Strong F-K effect strain reduces separation between Eg and Eg L F-K regime in low absorption background Expected mod. depth: 10dB @ >30GHz Experimental mod. depth: 10dB Experimental bandwidth: 1.2 GHz Ultra low power consumption: 25 pJ/bit J.F. Liu, M. Beals, A. Pomerene, S. Bernardis, R. Sun, J. Cheng, L. C. Kimerling, and J. Michel, ”Waveguide- integrated, ultra-low energy GeSi electro-absorption modulators,” Nature Photonics 2, 433 (June 2008) Electro Absorption Modulator
- 18. AIM Academy Si ridge waveguide – low loss strain reduces separation between Eg and Eg L F-K regime in low absorption background Mod. depth: 4-7.5dB @ >30GHz Max. experimental mod. depth: 7.5dB Low power consumption: 100 fJ/bit N.-N. Feng et al., ” 30GHz Ge electro-absorption modulator integrated with 3μm silicon-on-insulator waveguide,” Optics Express 72, 7062 (April 2011) Electro Absorption Modulator Franz-Keldysh Effect in GeSi Electro Absorption Modulator
- 19. AIM Academy Modulator Comparison Modulator Type Footprint Power Consumption Wavelengths Range Applications Si Mach Zehnder > 500 mm2 > 10pJ/bit large, tunable Active Optical Cable, Telecom Si Ring modulator < 10 mm2 > 5fJ/bit (w/o heating) single wavelength Telecom, On- chip Integration Ge EA modulator < 10 mm2 25fJ/bit ~ 15nm range On-chip Integration Plasmonic modulator 2.5 mm2 < 50fJ/bit large, ~ 1mm On-chip Integration Modulator Comparison
- 20. AIM Academy Active Photonics: Light Sources and Lasers IR light source: SOI waveguides Laser: DWDM, sub-mm structures interferometric structures III-V monolithic integration Si hybrid laser Ge laser Frequency comb based light sources K. Vahala et al., APL, v.84(7), (2004). J. Bowers et al., IEEE Phot. Tech. Lett., v.18(10), (2006). 20 Active Photonics: Light Sources and Lasers
- 21. AIM Academy Monolithic Integration of III-V laser on SiGe/Si Long RT CW-lifetime GaAs laser: 4 hrs pre-growth CMP of SiGe graded layer TDD=2x106 cm-2 λ=858 nm, d=0.4, Jth=269 A/cm2 InGaAs laser λ=890 nm, d=0.26, Jth=700 A/cm2 M.E. Groenert, E.A. Fitzgerald et al., “Monolithic integration of room-temperature cw GaAs/AlGaAs lasers on Si substrates via relaxed graded GeSi buffer layers,” J. Appl. Phys., v.93(1), pp.362-367 (2003). M.E. Groenert, E.A. Fitzgerald et al., “Improved room-temperature continuous wave GaAs/AlGaAs and InGaAs/GaAs/AlGaAs lasers fabricated on Si substrates via relaxed graded GexSi1-x buffer layers,” J. Vac. Sci. Tech. B, v.21(3), pp.1064-1069 (2003). misfit dislocation Monolithic Integration
- 22. AIM Academy Si waveguide bonded to AlGaInAs QWs SOI ridge waveguide, SiO2/Ta2O5 facet mirror Overlap: Si=0.6-9, QWs=0.01-0.06 Hybrid integration: zero alignment tolerance Bonding: low T oxygen plasma-assisted wafer bonding T=250 °C tolerate Thermal Expansion Mismatch <5 nm reactive oxide layer Endures dicing, facet polishing CW lasing (l=1568 nm) Optical Pumping Pth=23 mW, Pmax=4.5 mW Electrical Injection Ithres=65 mA, Pmax=1.8 mW, eff=0.13 H. Park, J.E. Bowers et al, Opt. Exp., v.13(23),pp.9460-9464 (2005). A.W. Fang, J.E. Bowers et all., IEEE Phot. Tech. Lett., v. 18(10), pp.1143-1145 (2006). A.W. Fang, J.E. Bowers et al., Opt. Exp., v.14(20), pp.9203-9210 (2006). A.W. Fang, J.E. Bowers et al., Matls. Today, v.10(7-8), pp.28-35 (2007). Hybrid Integration of III-V laser on SiGe/Si Hybrid Integration
- 23. AIM Academy Germanium Laser Ge-on-Si for Si integration High n-doping required Demonstrated lasing from 1520 to 1700 nm with electrical pumping Demonstrated 8mW laser peak power at 1620nm J.F. Liu, X. Sun, R. Camacho-Aguilera, L. C. Kimerling, J. Michel, “A Ge-on-Si laser operating at room temperature” Optics Lett. 35 (2010) R. E. Camacho-Aguilera, Y. Cai, N. Patel, J. T. Bessette, M. Romagnoli, L.C. Kimerling, and J. Michel, “An electrically pumped Germanium laser”, Opt. Exp. 20, 11316 (2012) L-I curve at 300K Germanium Laser
- 24. AIM Academy QW and QD Lasers on Silicon GaAs directly grown on Si InGaAs QW with n and p contact Current emission wavelength between 800nm and 1100nm Electroluminescence demonstrated Optically pumped lasing reported L. C. Chuang et al., “InGaAs QW Nanopillar Light Emitting Diodes Monolithically Grown on a Si Substrate,“ OSA/CLEO/QELS 2010 CMFF6 InGaAs Nanopillar QW Laser InAs QD Laser Alan Y. Liu et al., “High performance continuous wave 1.3 mm quantum dot lasers on silicon“ APPLIED PHYSICS LETTERS 104, 041104 (2014) QW and QD Lasers on Silicon
- 25. AIM Academy Frequency Comb Generation T. Herr, et al., NP, 145, 2014 & K. Saha, et al., OE, 1335, 2013 Frequency Comb Generation
- 26. AIM Academy Near IR Comb Generation using SiN Nanophotonic Optical Parametric Oscillator • SiN • CMOS-compatible material • n~2, on-chip, high confinement waveguides • Very low propagation losses (0.1 dB/cm) • Broad transparency window • n2 ~ 2x10-19 (cm2 /W), γ ~ 1 W-1 m-1 • Source with many independent wavelengths in the C-band • Suitable for use in Si network-on-chip • Flexible pump wavelength: visible to IR J. S. Levy, A. Gondarenko, et al., “CMOS-compatible multiple-wavelength oscillator for on-chip optical interconnects,” Nature Photonics., v.4(1), pp. 37-40 (2010). Near IR Comb Generation using SiN
- 27. AIM Academy Book Recommendation Handbook of Silicon Photonics CRC Press Series in Optics and Optoelectronics Published: April 26, 2013 by Taylor & Francis Editor(s): Laurent Vivien, Lorenzo Pavesi