Karlsruhe Series in Photonics & Communications, Vol. 15 Dietmar Korn Silicon-Organic Hybrid Platform for Photonic Integrated Circuits Dietmar Korn Silicon-Organic Hybrid Platform for Photonic Integrated Circuits Integrated Photonic for Platform Hybrid Silicon-Organic Korn Dietmar Dietmar Korn Silicon-Organic Hybrid Platform for Photonic Integrated Circuits Karlsruhe Series in Photonics & Communications, Vol. 15 Edited by Profs. J. Leuthold, W. Freude and C. Koos Karlsruhe Institute of Technology (KIT) Institute of Photonics and Quantum Electronics (IPQ) Germany Silicon-Organic Hybrid Platform for Photonic Integrated Circuits by Dietmar Korn Dissertation, Karlsruher Institut für Technologie (KIT) Fakultät für Elektrotechnik und Informationstechnik, 2013 Impressum Karlsruher Institut für Technologie (KIT) KIT Scientific Publishing Straße am Forum 2 D-76131 Karlsruhe KIT Scientific Publishing is a registered trademark of Karlsruhe Institute of Technology. Reprint using the book cover is not allowed. www.ksp.kit.edu This document – excluding the cover – is licensed under the Creative Commons Attribution-Share Alike 3.0 DE License (CC BY-SA 3.0 DE): http://creativecommons.org/licenses/by-sa/3.0/de/ The cover page is licensed under the Creative Commons Attribution-No Derivatives 3.0 DE License (CC BY-ND 3.0 DE): http://creativecommons.org/licenses/by-nd/3.0/de/ Print on Demand 2015 ISSN 1865-1100 ISBN 978-3-7315-0430-6 DOI 10.5445/KSP/1000048792 Silicon-Organic Hybrid Platform for Photonic Integrated Circuits Zur Erlangung des akademischen Grades eines DOKTOR-INGENIEURS der Fakultät für Elektrotechnik und Informationstechnik des Karlsruher Instituts für Technologie genehmigte DISSERTATION von Dipl.-Phys. Dietmar Korn aus Potsdam Tag der mündlichen Prüfung: 02.10.2013 Hauptreferent: Prof. Dr. sc. nat. Juerg Leuthold Korreferent: Prof. Dr.-Ing. Dr. h.c. Wolfgang Freude Table of Contents Zusammenfassung................................................................................................ i Preface ................................................................................................................. xi Achievements of the Present Work ................................................................. xv Technology Platform Development ..................................................... xv Demonstrations .................................................................................... xvi Photonic Integrated Circuit Designs .................................................. xvii 1 Introduction – Integration Increases Performance .................................. 1 1.1 Available Platforms for Photonic Integration ........................................ 1 1.2 Employing CMOS-Based Silicon Photonic Processes .......................... 3 1.3 Light Generation Using the SOI Platform ............................................. 4 1.4 Data Communication Using the SOI Platform ...................................... 7 2 Theoretical and Technological Background .............................................. 9 2.1 Fundamentals ......................................................................................... 9 2.1.1 Maxwell’s Equations .................................................................. 10 2.1.2 Linear Polarization ..................................................................... 11 2.1.3 Nonlinear Polarization ................................................................ 12 2.2 Waveguiding Structures on SOI ........................................................... 13 2.2.1 Silicon Properties and Silicon-Organic Hybrid Approach ......... 13 2.2.2 SOI Waveguides ......................................................................... 16 2.2.3 SOI Standard Structures ............................................................. 23 2.3 Stimulated Emission on SOI ................................................................ 30 2.3.1 General Dye Properties............................................................... 30 2.3.2 Lasing from Dyes ....................................................................... 33 2.3.3 Dyes on SOI Wafers ................................................................... 34 2.4 Electro-Optic Modulation on SOI ........................................................ 35 2.4.1 Plasma Effect in SOI Structures ................................................. 36 2.4.2 Linear Electro-Optic Effect in SOH Structures.......................... 37 2.5 SOH Travelling Wave Modulator ........................................................ 43 2.5.1 Modulator Properties .................................................................. 43 2.5.2 Modulator Modeling ................................................................... 45 Table of Contents 2.5.3 Walk-Off Between Optical and Electrical Wave ....................... 48 2.5.4 RC Limitation of the Strip-Loaded Slot ..................................... 48 2.5.5 Impedance Mismatch .................................................................. 51 2.5.6 Travelling Wave Losses ............................................................. 53 2.6 Modulation and Multiplexing Techniques ........................................... 61 2.6.1 Complex Amplitude Modulation ................................................ 62 2.6.2 Complex Amplitude Demodulation ........................................... 62 3 Light Emission with SOH Devices ............................................................ 65 3.1 Introduction .......................................................................................... 66 3.2 Results .................................................................................................. 67 3.2.1 Concept and Fabrication of Silicon-Organic Hybrid Lasers ...... 67 3.2.2 Characterization and Experimental Proof of Lasing .................. 69 3.2.3 Influence of Waveguide Geometry ............................................ 72 3.2.4 Dynamic Emission Behavior ...................................................... 74 3.3 Discussion ............................................................................................ 76 3.4 Methods ................................................................................................ 77 3.4.1 Fabrication of Silicon-Organic Hybrid Lasers ........................... 77 3.4.2 Experimental Demonstration of Laser Emission ....................... 78 3.4.3 Estimation of Emission Power Levels ........................................ 80 3.4.4 Estimation of Pump Power Levels ............................................. 80 3.4.5 Resonator Characteristics and Threshold Pump Power ............. 81 3.4.6 Optically Induced Losses and Dynamical Behavior .................. 84 3.4.7 Summary of Resonator and Laser Characteristics ..................... 85 3.5 Supplementary Information .................................................................. 88 3.5.1 Waveguide Properties ................................................................. 90 3.5.2 High-Resolution Spectra ............................................................ 91 3.5.3 Resonator Loss and Pump Threshold ......................................... 92 3.5.4 Optically Induced Nonlinear Losses .......................................... 94 4 Modulation with SOH Devices .................................................................. 97 4.1 MZM Modulator Based on Organic Crystals ...................................... 97 4.1.1 Introduction ................................................................................ 98 4.1.2 SOH Concept Employing Organic Crystals ............................. 100 4.1.3 SOH Device Fabrication and Experiments .............................. 103 4.1.4 SOH Modulator for Data Generation ....................................... 108 4.1.5 Conclusions .............................................................................. 110 Table of Contents 4.2 IQ Modulator Based on Chromophores in a Polymer ....................... 111 4.2.1 Introduction .............................................................................. 111 4.2.2 Structure of the Silicon-Organic Hybrid IQ Modulator ........... 113 4.2.3 Demonstrations ......................................................................... 116 4.2.4 Discussion and Conclusion ...................................................... 121 4.3 SiGe-Based Driver Circuit for SOH Modulators ............................... 123 5 Modulation with Benchmarking Devices ............................................... 125 5.1 Plasma-Effect Based Device on Standard SOI Platform ................... 125 5.1.1 Introduction .............................................................................. 126 5.1.2 Device Design and Fabrication ................................................ 126 5.1.3 Modulator and Detector Performance ...................................... 128 5.1.4 Conclusion ................................................................................ 129 5.2 Electro-Optic Effect-Based Device on GaAs Platform ..................... 130 5.2.1 Introduction .............................................................................. 130 5.2.2 GaAs Modulator ....................................................................... 132 5.2.3 Experimental Setup .................................................................. 133 5.2.4 Experimental Results ................................................................ 134 5.2.5 Conclusion ...............................................................................