INTRODUCTION TO OPTICS LECTURE NOTES

Transcript

1 OPTOSCI LTD INTRODUCTION TO OPTICS INTRODUCTION TO OPTICS LECTURE NOTES 1. INTRODUCTION TO OPTICS Introduction HISTORICAL BACKGROUND The seventeenth century The nineteenth century The twentieth century ELECTROMAGNETIC THEORY Electromagnetic phenomena The wave equation in free space ELECTROMAGNETIC WAVES Solutions for the electric field Transverse nature of the electric field Solutions for the magnetic field Why no 'luminiferous aether'? Electromagnetic waves in materials Plane waves and other forms Power flow and the Poynting vector Standing waves Group velocity OPTICAL SOURCES AND THE PARTICLE PROPERTIES OF LIGHT The Particle Properties of Ligh The Electromagnetic Spectrum Generation of Electromagnetic Radiation Electromagnetic Properties of Atoms Radiation From Atoms and M ec es X-rays and Gamma Rays Linewidth Coherence POLARISATION Linear states of polarisation Circular and Ellipt al S tes of Polarisation Birefringence Polarisers REFLECTION AND EFRACTI Introd ction Geometrical laws of eflection and refraction A wa e-picture of ref ection and refraction Bound ry condition for the electric and magnetic field vectors Relations i betw en the continuity conditions and the laws of reflection and refraction The Fresnel Equations The Brewster angle Total internal reflection Energy associated with the evanescent wave Form of the evanescent wave Phase changes on reflection The Goos-Haenchen shift INTERFERENCE Young's slits The Mach-Zehnder interferometer...54

2 OPTOSCI LTD INTRODUCTION TO OPTICS 8.3 Visibility of interference Effect of polarisation on visibility Effect of coherence on visibility DIFFRACTION...61 APPENDIX A...63 Tutorial - Wave And Particle Properties Of Light...63 APPENDIX B...64 Tutorial Solutions - Wave And Particle Properties Of Light...64

3 OPTOSCI LTD REFLECTION & REFRACTION REFLECTION & REFRACTION STUDENT MANUAL 2. THEORY Snell s law The Fresnel Equations APPARATUS LASER SAFETY Operational Hazard - Semiconductor laser diodes THE EXPERIMENTAL SYSTEM Assembly of the system Establishment of the required polarisation state Operation of the system Angular Measurements Optical Power Measurements EXPERIMENTAL EXERCISES Snell s Law Snell s Law - low to high index Snell s Law - high to low index Analysis of the Snell s Law meas rements Fresnel Equations - Reflectance and Tra smittanc Determination of the Correction Factors for the C culation of Reflectance and Transmission from Power Measurements Vertical Polarisation - low to high d x Horizontal Polarisation - low t high ind Vertical Polarisation - high to ow index Horizontal Polarisation - high t low index Analysis of results APPENDIX A APPENDIX R&R: ALIGNMENT AND SET-UP OF R&R...17 RR1: Basic Assembly Pro edure RR2: Equalising the Laser L unch ower for Horizontal & Vertical Polarisation...19 RR3: Alignmen of the T ble and t Semi-Cylindrical Optical Element...20 APPENDIX LA&C: LASER A IGNMENT & COLLIMATION...22 LA&C1 Cen alising the La r Beam...22 LA&C2 Collim ing or F using the Laser Beam...22

4 OPTOSCI LTD OPTICAL POLARISATION OPTICAL POLARISATION STUDENT MANUAL 2. THEORY Introduction to ordered States of Polarisation Special and General cases of ordered polarisation Creation of ordered SOPs - Linear SOP using dichroic polymer sheet Creation of ordered SOPs - Birefringence Measurement of SOP Stokes parameters The Stokes parameters and The Poincaré Sphere APPARATUS LASER SAFETY Operational Hazard - Semiconductor laser diod s THE EXPERIMENTAL SETUP EXPERIMENTAL EXERCISES Malus Law Alignment of the analyser Malus Law Investigation of a half-wave plate Alignment of wave plates ident cation their a s Half-wave plate characteristics Investigation of quarter-wave plates Identification of axes Alignment of wave plates with heir axes t 45º to an incident linear state Investigation of two quarter-w ve plates in eries Measurement of SOP, Stokes p rameters and the polarisation ellipse linear polarisation Measurement of SOP Stokes para t and the polarisation ellipse elliptical polarisation Measurement of SOP, Stokes p rameters and the polarisation ellipse arbitrary wave plate Investigation of strain bi fringence strain measurements...18 APPENDIX POL: LASER POWER OPTIMISATION...19 APPENDIX LA&C: LASER LIGNMENT & COLLIMATION...20 LA&C1 Centra sing th Laser Be m...20 LA&C2 Coll mating or Foc sing the Laser Beam...20

5 OPTOSCI LTD OPTICAL DIFFRACTION OPTICAL DIFFRACTION STUDENT MANUAL 2. THEORY Introduction Fresnel and Fraunhofer Diffraction Fraunhofer Diffraction at a Slit Fraunhofer Diffraction at a Circular Aperture Fresnel Diffraction at Slits and Apertures Diffraction at Gratings APPARATUS LASER SAFETY Operational Hazard - Semiconductor laser diod s THE EXPERIMENTAL SYSTEM Slits & Apertures Set Up Measurement of Diffraction Patterns Diffraction Gratings Reflection Gratings Set-Up Transmission Gratings Set-Up Measurement of Angles Grating Diffra ion EXPERIMENTAL EXERCISES Fraunhofer Diffraction at a Slit Fraunhofer Diffraction at a Cir ular Aper ure Fresnel Diffraction at an Apertu e Diffraction Gratings Reflection Grating Expe im ts Transmission Grating Experimen APPENDIX LA&C: LASER ALIGNMENT & COLLIMATION...25 LA&C1 Centralising th aser Beam...25 LA&C2 Collimating or Focu ing the Laser Beam...25 LA&C3 Collimating or F using th Beam of the Laser Diode Module Style #2 (LDM#2)...26 REFERENCES

6 OPTOSCI LTD OPTICAL INTERFERENCE & COHERENCE OPTICAL INTERFERENCE & COHERENCE STUDENT MANUAL 2. THEORY Coherence Introduction Time Coherence in Practice Linewidth Linewidth Broadening Interference between two coherent waves Interference between partially coherent fields APPARATUS LASER SAFETY Operational Hazard Helium Neon Laser and Semiconductor laser diode THE EXPERIMENTAL SYSTEM Construction of the interferometer Measurement of fringe visibility and spacing Measurement of coherence length EXPERIMENTAL EXERCISES Construction of a Michelson interf romet Quality assessment of optical elemen Coherence of a Helium Neon Laser Investigation of the coherence fu tion f a Fabry-Pérot cavity laser diode Coherence of conventional sour es (option l)...18 APPENDIX A - INTERFEROMETER A IGNMENT...19 A.1 Interferometer Set-Up: He iu Neon Laser...19 A.2 Interferometer Set-Up: Semicondu Laser Diode...24 A.3 Centralising the Lase Beam A.4 Collimating or Foc ng the Beam of the Laser Diode Module Style #2 (LDM#2)...26 REFERENCES

7 OPTOSCI LTD PRINCIPLES OF OPTICAL WAVEGUIDING PRINCIPLES OF OPTICAL WAVEGUIDING LECTURE NOTES 1. INTRODUCTION TO OPTICS Introduction HISTORICAL BACKGROUND The seventeenth century The nineteenth century The twentieth century ELECTROMAGNETIC THEORY Electromagnetic phenomena The wave equation in free space ELECTROMAGNETIC WAVES Solutions for the electric field Transverse nature of the electric field Solutions for the magnetic field Why no 'luminiferous aether'? Electromagnetic waves in materials Plane waves and other forms Power flow and the Poynting vector Standing waves Group velocity POLARISATION Linear states of polarisation Circular and Elliptical States of Pola sation Birefringence Polarisers OPTICAL SOURCES AND THE PARTICLE PR ERTIES OF LIGHT The Particle Properties of L ght The Electromagnetic Spectrum Generation of Elect magnetic di ion Electromagnetic Prope ti of Atoms Radiation From Atoms and M l les X-rays and Gamma Ray Linewidth Coherence REFLECTION AN EFRACTIO Introd ction Geometrical laws of eflection and refraction A wa e-picture of ref ection and refraction Bound ry condition for the electric and magnetic field vectors Relations bet en the continuity conditions and the laws of reflection and refraction The Fresnel Equations The Brewster angle Total internal reflection Energy associated with the evanescent wave Form of the evanescent wave Phase changes on reflection The Goos-Haenchen shift INTERFERENCE Young's slits The Mach-Zehnder interferometer...54

8 OPTOSCI LTD PRINCIPLES OF OPTICAL WAVEGUIDING 8.3 Visibility of interference Effect of polarisation on visibility Effect of coherence on visibility DIFFRACTION OPTICAL WAVEGUIDES Total internal reflection The two-dimensional slab waveguide The formation of waveguide modes Number of allowed waveguide modes Field distributions for the guided modes The waveguide parameters Mode cut-off conditions Normalised effective index and normalised film thickness TE and TM modes The asymmetric slab waveguide The eigenvalue equation Graded index slab waveguides Prism coupling OPTICAL FIBRES APPENDIX A Tutorial 1 - Wave And Particle Properties Of Light...84 Tutorial 2 - Optical Waveguides APPENDIX B Tutorial Solutions 1 - Wave And Particle Propert Of Light Tutorial Solutions 2 - Optical Waveguides

9 OPTOSCI LTD OPTICAL WAVEGUIDING OPTICAL WAVEGUIDING STUDENT MANUAL 2. THEORY Planar step index waveguides Graded index waveguides Prism coupling APPARATUS LASER SAFETY Operational Hazard - Semiconductor laser diodes THE EXPERIMENTAL SYSTEM Aims and Objectives Assembly and operating instructions for the experimental system Assembly of the system Establishment of the required polarisation state Operation of the system EXPERIMENTS AND EXERCISES Investigation of Step Index Waveguides Determination of the mode structur of a step index planar waveguide Observation of the substrate modes Coupling to the waveguide modes Observation and investigation he m-lines ( ode lines) Measurement of the coupling angles and m e effective indices for the TE polarisation state Measurement of the mode structure of the waveguide for the TM polarisation state Determination of the mod structu of the second step index waveguide provided (optional - on instructions from the laboratory upervisor) Determination of the step in ex waveguide parameters (i.e. the waveguide refractive index and thickness) from the measur d m de spe um Establishing the design o single mode step index waveguide Confirmation of your design of single mode waveguide Investigation of Grade n Waveguides Determination of the mode str cture of the graded index waveguide Determination of e wavegu de parameters of the graded index waveguide (the surface index and thickness) from the measur d mode pectrum Establish g design of single mode graded index waveguide Confirmation of sing mode op ation APPENDIX WAVE: OPTICA WAVEGUIDING SET-UP...18 WAVE1: Bas Assembly Pr cedure...18 WAVE2: Practica G i to Achieving Waveguiding...21 WAVE3: Angular Measurement Technique Using Micrometer...24 APPENDIX LA&C: LASER ALIGNMENT & COLLIMATION...25 LA&C1: Centralising the Laser Beam...25 LA&C2: Collimating or Focusing The Laser Beam...25

10 OPTOSCI LTD FIBRE OPTIC COMMUNICATIONS FIBRE OPTIC COMMUNICATIONS LECTURE NOTES CHAPTER 1 : INTRODUCTION TO OPTICAL FIBRE COMMUNICATIONS Introduction Historical perspective Fibre optic communications systems Why fibre optics CHAPTER 2 : THE OPTICAL COMMUNICATIONS CHANNEL Introduction Optical fibre for communications systems Attenuation and link length limits in fibre optic channe Attenuation in optical fibre Fibre attenuation mechanisms Absorption Scattering The wavelength dependence of attenuation in silica fib Fibre cable losses - radiation/ bend loss Other sources of loss in optical fibre channels Implications of attenuation Pulse spreading, dispersion and bit rate/ distanc limits i optical fibre links Introduction Pulse spreading/ dispersion in sing mode op fibre Physical origins of intramodal disp rsion Material dispersion Waveguide dispersion The total magnitude of pulse spreading in si g mode optical fibres Pulse spreading in multimode op ical fi - intermodal time delay effects Multimode step index fib Multimode graded index f re Multiple sources f pulse spr ding Implications of pulse spr ding Analogue transmission Summary CHAPTER 3 : OPTICAL SOURCES FOR FIBRE OPTIC COMMUNICATIONS SYSTEMS Introduction Structure & operating principle of semiconductor optical sources for telecommunications Light generation in a s mple p-n junction Doub e hetero-junction for efficient light generation and collection Mater l systems and f brication Lasers an LEDs - the differences Characteristics of LEDs Power/ current characteristics Output power and launched power Modulation Bandwidth/ Maximum bit rate Wavelength characteristics Laser diode characteristics Power/ current characteristics Output power and launched power Modulation bandwidth/ maximum bit rate Wavelength characteristics Fabry Perot Cavity (FPC) Lasers...36

11 OPTOSCI LTD FIBRE OPTIC COMMUNICATIONS Distributed Feedback (DFB) Lasers Summary...40 CHAPTER 4 : OPTICAL DETECTION AND OPTICAL RECEIVERS Introduction Principles of p-n and pin diode structures Principles of photodiode detection Principles of avalanche photodiodes (APDs) Characteristics of photodiodes and photodiode receivers Quantum efficiency and responsivity Wavelength dependence of the responsivity Response speed and bandwidth Noise in photodiode detectors Signal shot noise The dark current shot noise Thermal noise Signal to noise ratio and detection sensitivity Thermal noise limited detection Dark current shot noise limits Quantum or shot noise limited detection Digital optical receivers Avalanche photodiodes Power penalties Practical photodiode detector circuits Summary CHAPTER 5 : THE FIBRE OPTIC COMMUNICATIONS SYSTEM Introduction System performance System design and analysis Summary REFERENCES APPENDIX A: TUTORIALS APPENDIX B: TUTORIAL SOLUTIONS

12 OPTOSCI LTD FIBRE OPTIC COMMUNICATIONS FIBRE OPTIC COMMUNICATIONS STUDENT MANUAL 2. PRINCIPLES OF FIBRE OPTIC COMMUNICATIONS SYSTEMS Attenuation Limits Dispersion Limits PRINCIPLES OF FIBRE DISPERSION AND SYSTEM RESPONSE MEA UREMENTS Frequency domain response measurements Time domain response measurements Calculation of the BW.L and BR.L products Measurement of the material and intermodal dispersion contribu ons DESIGN OF THE EDUCATOR KIT APPARATUS Equipment supplied Additional equipment to be supplied by the user LASER SAFETY Operational Hazard - Semiconductor Laser Diode OPERATING INSTRUCTIONS Front Panel Layout Before Switching On Use of Optical Fibres Setting the Bias Points for the Optical Sources Use of the Waveform Generator Before Switching Off EXPERIMENTS Comparison of LED and Laser Diode C aracteris cs Optical Output Power against Drive Current Launched Optical Power Attenuation in Optical Fibre Link Optical Fibre Connector Lo s Attenuation of the Optical gnal over t e Link Length Determination of Fibre Link ength and Fibre Attenuation Coefficient Determination of Att uation Limited Link Lengths Exercises Bandwidth and Fibre Dispersion M surements Time domain measurem ts Frequency Domain Measur ment Exercises APPENDIX A: DISPERSION PHENOMENA IN OPTICAL FIBRES...17 The Origins o Dispersio Step and Frequency Respon es...19 Dispersion a d Bit Error Ra e...21 Dispersion Ef ects - A Brief nvestigation...24 APPENDIX B: EQ ATING AN AMPLITUDE DIVIDED SIGNAL TRAVERSING TWO DIFFERENT PATHS...27 APPENDIX C: FIBRE LINK LENGTH MEASUREMENT USING BER(COM)...28 C.1 Theory...28 C.2 Measurement of Fibre Length with BER(COM) Method C.3 Measurement of Fibre Length with BER(COM) Method C.4 Calculation of the Fibre Attenuation per km for the Optical Sources...30 APPENDIX: WORKING WITH OPTICAL FIBRES (WOF) General Use of Optical Connectors...31

13 OPTOSCI LTD BER(COM) EYE DIAGRAMS & BIT ERROR RATES IN OPTICAL COMMUNICATIONS BER(COM) STUDENT MANUAL 2. THEORY Threshold Detection and BER BER, SNR, Sensitivity and Power Penalties Eye Diagrams Measurement and estimation of BER APPARATUS DESCRIPTION LASER SAFETY Operational Hazard - Semiconductor Laser Diode OPERATING INSTRUCTIONS Before Switching On Care of Optical Fibres Operation of the PRBS to generate Eye Diagrams from ED-COM Transmission Links Acquisition of Signal Variation Histograms, Noise Var nce Q-factor and BER Switching Off EXPERIMENTAL EXERCISES Eye Diagrams for the direct output of the PRBS generato Eye Diagrams for transmission of th LED signal ov a 1m patchcord Investigation of the variation of bre leng f the LED transmitter Risetime, 80% Pulse Width and Jitter Investigation of the variation of fibre ngth for th LED transmitter Noise, Q-factors and BER Investigation of the eye diagrams f he laser transmitter Investigation of Q-factor and B R as a function of increasing link length Investigation of Q-factor and BER as a fun tion of increasing bit rate...21 APPENDIX A: PRBS Specific ion A.1 PRBS Specification APPENDIX B: FIBRE LINK LENGTH M ASUREMENT USING BER(COM)...23 B.1 Theory B.2 Measurement of Fibr Length w th BER(COM) Method B.3 Measurement of Fibre L ngth ith BER(COM) Method B.4 Calculatio of the F bre Atten ation per km for the Optical Sources...25 APPENDIX C: Result Table T mplates...26 C.1 Table T mplates for Ris time, 80% Pulse Width and Jitter Results...26 C.2 Table Templates for Q actor and BER Results...27 REFERENCES

14 OPTOSCI LTD OPTICAL NETWORK ANALYSIS OPTICAL NETWORK ANALYSIS LECTURE NOTES PART 1: OPTICAL TIME DOMAIN REFLECTOMETRY INTRODUCTION OPTICAL TIME DOMAIN REFLECTOMETRY The Basic Principles Spatial Resolution Signal to Noise Ratios and Dynamic Ranges USING THE OTDR The Basic Principles The OTDR as Line Tester Network Testing The OTDR in Sensing Using the OTDR - A Brief Overview VARIATIONS ON THE OTDR THEME OTDR Systems with Enhanced Resolution Improving the Average Power Improving Inherent Sensitivity: Photon Cou ting Improving Sensitivity: Using Optical Amplif ers OTDR Testing in the 1.6µm band OTDR Systems for Non-Linear O tical and Other Measurements CONCLUSIONS REFERENCES APPENDIX 1: COMMENTS ON EQUATION APPENDIX 2: EXPONENTIAL UNITS AND DEC ELS - DERIVATION OF EQUATION APPENDIX 3: COMMENTS ON EQUAT ON APPENDIX 4: SIGNAL TO NOISE RATIO AND D NAMIC RANGE...21 APPENDIX 5: TUTORIAL EXAM S ON OPTICAL TIME DOMAIN REFLECTOMETRY...22 APPENDIX 6: TUTORIAL EXAMPLES ON O DR - OUTLINE SOLUTIONS...27 PART 2: IN-LINE FIBRE OPTIC COMPONENTS INTRODUCTION THE OPTICA WAVEGU E DIRECT ONAL COUPLER Princ ples of Directional Coupling Wave ngth Response Identical Waveguides Wavele gth Flatteni g - Non-identical Waveguides Wavelength F ering - Non-identical Waveguides SINGLE MODE FUSED FIBRE COUPLERS Simple Couplers Wavelength Division Multiplexers Wavelength Flattened Couplers Specifications CONCLUSIONS...47 REFERENCES...48

15 OPTOSCI LTD OPTICAL NETWORK ANALYSIS OPTICAL NETWORK ANALYSIS STUDENT MANUAL 2. THEORY Basic principles of OTDR Rayleigh backscatter and OTDR signals from optical fibre Events in OTDR traces Fresnel reflections, dead zones and ghosts SNR, signal recovery and loss measurement resolution Spatial resolution, range resolution and event location Dynamic range, range and range / resolution trade-off Principles of OTDR trace analysis Splice Losses Networks Containing Couplers Dissimilar Fibres Summary of OTDR trace analysis APPARATUS DESCRIPTION LASER SAFETY Operational Hazard - Semiconductor Laser D ode OPERATING INSTRUCTIONS Use of the OTDR Unit Care of Optical Fibres EXPERIMENTS AND EXERCISES Aims and Objectives Investigation of a single point to point link Investigation of connector and s lice loss s and dissimilar fibres Investigation of bend losses Investigation of a network s ction ontai ng a fused fibre coupler Investigation of a simple n t ork Fault location and analysis APPENDIX A: SPECIFICATION O THE NETWORK COMPONENTS...22 APPENDIX B: SPECIFICATION OF HE COMPONENTS USED IN THE SAMPLE RESULTS..23 APPENDIX C: ANRITSU MW 076 MINI-OTDR SIMPLE OPERATING NOTES...24 APPENDIX WO : WORKING WITH OPTICAL FIBRES General Use of Op ical Connector...25 APPENDIX DB: ECIBELS Working with Decibels (db) Working with dbm...28

16 OPTOSCI LTD ERBIUM DOPED FIBRE AMPLIFIERS ERBIUM DOPED FIBRE AMPLIFIERS LECTURE NOTES ERBIUM DOPED FIBRE AMPLIFIERS INTRODUCTION PRINCIPLES OF ATOMIC RADIATION Photon - Material Interactions Spontaneous emission Absorption Stimulated emission The Einstein Coefficients Line Shape Transition Rates For Narrow Band Radiatio OPTICAL AMPLIFICATION - SMALL SIGNAL GAIN PUMPING MECHANISMS OPTICAL AMPLIFICATION - LARGE SIGNAL GAIN Introduction Four level systems Three level systems Issues of homogeneous and inhomogeneous lin broadening NOISE IN OPTICALLY AMPLIFIED SIGNALS Noise in Optically Amplified Signals The Noise Figure THE ERBIUM DOPED FIBRE MPLIFIER EDFA Structure and Principles Gain Characteristic of DFAs Noise Characteris cs and SNR Noise in Amplifier scades Noise Fi s for Amp ier Cascades CONCLUSIONS REFERENCE APPENDIX A DERIVATI N OF BEAT NOISE TERMS...41 A.1 Derivation of Beat Noise Terms...41 A.2 Signal-ASE beat noise...42 A.3 ASE-ASE Beat Noise...43 APPENDIX B: TUTORIALS APPENDIX C: TUTORIAL SOLUTIONS

17 OPTOSCI LTD ERBIUM DOPED FIBRE AMPLIFIERS ERBIUM DOPED FIBRE AMPLIFIERS STUDENT MANUAL 2. THEORY OF EDFAS Introduction Gain Characteristics Noise and SNR in EDFAs APPARATUS DESCRIPTION LASER SAFETY OPERATING INSTRUCTIONS Before Switching On Care of Optical Fibres Operation of the Signal Source / Photoreceiver Unit Operation of the EDFA Unit Switching Off EXPERIMENTS Investigation of EDFA gain and power haracteri ics Calibration of the fixed attenuator Gain and power out versus input s gnal pow Output signal power and gain ver s pum power Investigation of the ASE and EDFA noise charact istics Overview of noise investigation techniques Investigation of the receiver nois Measurement of ASE levels (n signal) Investigation of ASE noise lev ls (no sign ) Measurement of the ASE level a functi n of input signal power Investigation of Signal ASE beat no Investigation of Signal-ASE eat noise using an ASE rejection filter APPENDIX WOF: WORKING WITH OPTICAL FIBRES (WOF) General Use of Optical Connec rs APPENDIX DB: DECIB LS Working w th Decibels ( B) Working ith dbm

18 OPTOSCI LTD PRINCIPLES OF LASERS PRINCIPLES OF LASERS LECTURE NOTES SECTION 1: THE LASER AN OPTICAL OSCILLATOR OVERVIEW OUTPUT POWER CHARACTERISTICS SPATIAL OUTPUT CHARACTERISTICS - TRANSVERSE MODES SPECTRAL CHARACTERISTICS OF THE LASER OUTPUT COHERENCE PROPERTIES OF THE LASER OUTPUT TEMPORAL CHARACTERISTICS OF THE LASER OUTPUT Relaxation oscillations Q Switching REFERENCES SECTION 2: FIBRE RING LASER THEORY INTRODUCTION THEORY OF OPERATION- RATE EQUATIONS STEADY-STATE CONDITIONS DYNAMIC CONDITIONS REFERENCES SECTION 3: ERBIUM DOPED FIBRE AMPL FIER INTRODUCTION PRINCIPLES OF ATOMIC RADIATION Photon - Material Interaction The Einstein Coefficients Line Shape Transition Rates For N row Band Radiation OPTICAL AMPLIFICATION - SMAL SIGNAL GAIN PUMPING MECHANISMS OPTICAL AMPLIFICATION - LARG SIGNAL GAIN Introduction Four level ms Three vel systems [2] Issue of homogeneo and inhomogeneous line broadening NOISE IN OPTICALLY AMPLIFIED SIGNALS Noise in ptically mplified Signals The Noise Figure THE ERBIUM DOPED FIBRE AMPLIFIER - EDFA Structure and Principles Gain Characteristics of EDFAs Noise Characteristics and SNR Noise in Amplifier Cascades CONCLUSIONS REFERENCES...63

19 OPTOSCI LTD PRINCIPLES OF LASERS PRINCIPLES OF LASERS STUDENT MANUAL 2. THEORY OF LASER POWER CHARACTERISTICS Overview Mathematical analysis General Laser Theory Mathematical analysis Fibre Laser Theory Steady State Output Conditions Dynamic Output Conditions APPARATUS DESCRIPTION LASER SAFETY Operational Hazard - 980nm and 1550nm laser radiation OPERATING INSTRUCTIONS Before Switching On Care of Optical Fibres Operation of the EDFA/Photoreceiver Unit Switching Off EXPERIMENTAL EXERCISES Small signal amplification in the g n mediu Calibration of the attenuators Calibration of the variable in-line attenuator Calibration of the fixed attenuator Measurement of the laser output ar teristics Dynamic Response - Relaxation Oscillatio s and Laser Onset Time Investigation of the oscillation requency a a function of pump power Investigation of laser nset time Effects of intra-cavity lo n laser onset time APPENDIX WOF: WORKING WITH OP CAL FIBRES (WOF) General Use of Optical Conne rs APPENDIX DB: DECIBELS Working w h Decibels db) Working ith dbm APPENDIX A: DETERMINA ION OF SLOPE EFFICIENCY & THRESHOLD GAIN...29 APPENDIX B: MEAS EMENT OF SMALL SIGNAL AMPLIFICATION IN THE GAIN MEDIUM USING AN ED-AMP SOURCE/RECEIVER...30 APPENDIX C: SMALL SIGNAL GAIN OF EDFA AS A FUNCTION OF THE PUMP POWER...31

20 OPTOSCI LTD PRINCIPLES OF LASERS PRINCIPLES OF LASERS (MODULE) STUDENT MANUAL 1. INTRODUCTION THEORY OF LASER POWER CHARACTERISTICS Overview Mathematical analysis General Laser Theory Mathematical analysis Fibre Laser Theory Steady State Output Conditions Dynamic Output Conditions APPARATUS DESCRIPTION LASER SAFETY Operational Hazard - 980nm and 1550nm laser radiation OPERATING INSTRUCTIONS Before Switching On Care of Optical Fibres Operation of the EDFA/Photoreceiver Unit Operation of the Signal Source / Photorecei er Unit Switching Off EXPERIMENTAL EXERCISES Measurement of small signal amplific ion in th gain medium Calibration of the attenuators Calibration of the variable in-line attenu Calibration of the fixed attenu or Measurement of the laser ou put charac eristics Dynamic Response - Relaxati n Oscilla ions and Laser Onset Time Investigation of the s llation f ncy as a function of pump power Investigation of laser on time Effects of intra-cavity loss on s onset time APPENDIX WOF: WORKING W TH OPTICAL FIBRES (WOF) General Use of Optical Connect s...25 APPENDIX DB: DECIBE S Worki g with Decibels (db) Workin with dbm APPENDIX A: D TERMINATION OF SLOPE EFFICIENCY & THRESHOLD GAIN...30

21 OPTOSCI LTD ED-WDM: WDM COMPONENTS ED-WDM: WDM COMPONENTS LABORATORY MANUAL 2. NOTES ON WDM SYSTEMS AND THEIR COMPONENTS Introduction WDM systems The General Principle of WDM Dense WDM (DWDM) Systems Coarse WDM (CWDM) Systems nm / 1550nm duplex systems Fused Biconical Taper (FBT) Fibre Components The optical waveguide directional coupler Singlemode fused fibre couplers Micro & Bulk Optic Components Introduction WDM devices (DWDM & CWDM) Isolators Circulators Fibre Bragg Gratings Optical Connectors Practical Component Packages APPARATUS DESCRIPTION Electronics Rack Power/ communications module Laser Diode Modules Power Meter Module Optical Components Rack Terminations Module Passive Component Modules Use of Optical Fibres EXPERIMENTAL EXERCIS (WDM COMPONENTS) Laser Characterisation Characterising the FBT 50/50 Coupler and establishing the Basic Measurement Set-Up FBT Coupler Using the FBT Co pler as part f the Measurement System Connectors minatio FBT Cou ler FBT WDM Isolator Circulators DWDM Modules...35 Exercise Bragg Grating...37 REFERENCE...39

22 OPTOSCI LTD ED-WDM: DWDM SYSTEMS ED-WDM: DWDM SYSTEMS LABORATORY MANUAL 2. APPARATUS DESCRIPTION Electronics Rack Laser Diode Modules Photoreceiver Module VOA Module Optical Components Rack Passive Component Modules Use of Optical Fibres Additional required equipment EXPERIMENTAL EXERCISES (DWDM COMPONENTS) Variable Optical Attenuator (VOA) DWDM Characterisation (Optional) EXPERIMENTAL EXERCISES (DWDM SYSTEMS) Assembly, Investigation and Characterisation o DWDM Systems Examination of Channel ADD function followed by a Channel DROP using the DWDMs as Add/Drop Multiplexers

23 OPTOSCI LTD ED-WDM: 1310/1550 WDM ED-WDM: 1310/1550 WDM LABORATORY MANUAL 2. NOTES ON OPTICAL FIBRE CHARACTERISTICS Introduction Optical fibre for communications systems Attenuation in fibre optic channels Attenuation in optical fibre Fibre attenuation mechanisms The wavelength dependence of attenuation in silica fibre Dispersion in optical fibre links Introduction Physical origins of chromatic (intramodal) dispersion The total magnitude of pulse spreading in single mode optical bres Pulse spreading in multimode optical fibre - intermodal dispersion APPARATUS DESCRIPTION Electronics Rack Laser Diode Modules Photoreceiver Module Optical Components RAck Passive Component Modules Optical Fibre Reel Use of Optical Fibres Additional required equipment EXPERIMENTAL EXERCISES (1310/1550 WDM OMPONENTS) Laser Characterisation Component Characterisation EXPERIMENTAL EXERCISES (13 0/1550 WDM SYSTEMS) Demonstration and Chara erisation of a 1310/1550nm WDM System Characterisation of a 1310/1550 m WDM bi-directional system Examination of Crosst lk on Weak Signals EXPERIMENTAL EXERCISES (FIBRE CHARACTERISTICS) Fibre Attenuation Fibre Len h Theo y Mea urement of Fibre ength with BER(COM) Method Meas rement of Fibre Length with BER(COM) Method Estimat n of Fibre roup Refractive Index at 1310nm Fibre Atten Co-efficient Chromatic Dispersion Background on Ring Resonators Background on Chromatic Dispersion Measurement Dispersion Measurements REFERENCES...29

24 OPTOSCI LTD ED-WDM: BRAGG GRATINGS ED-WDM: BRAGG GRATINGS LABORATORY MANUAL 2. NOTES ON FIBRE BRAGG GRATINGS APPARATUS DESCRIPTION Electronics Rack TEC Driver Module Optical Components Rack Tuneable Bragg Grating Module Use of Optical Fibres EXPERIMENTAL EXERCISES (BRAGG GRATINGS) Bragg Grating Tuneable Bragg Grating

25 OPTOSCI LTD ED-WDM: APPENDICES ED-WDM SERIES GENERAL APPENDICES APPENDIX 1: LASER SAFETY...1 APPENDIX 2: ITU CHANNEL DESIGNATIONS APPENDIX DB: DECIBELS Working with Decibels (db) Working with dbm APPENDIX WOF: WORKING WITH OPTICAL FIBRES General Use of Optical Connectors APPENDIX MOD: MODULATION SCHEME FOR LASER DRIVERS APPENDIX BER: BER(COM) INTRODUCTION THEORY Threshold Detection and BER BER, SNR, Sensitivity and Power Penalties Eye Diagrams Measurement and estimation of BER APPARATUS DESCRIPTION OPERATING INSTRUCTIONS Operation of the PRBS to generate Ey agrams Acquisition of Signal Variation Histograms, Noise ariance Q-factor and BER EYE DIAGRAMS FOR THE OUTPUT OF THE PRBS GENERATOR FIBRE LENGTH MEASUREME TS Theory Measurement of Fibre Length with BER(COM) Method Measurement of Fibre Len h with BER(COM) Method APPENDIX LVI: DFB LASER CHARACTERISATION...30 A. DFB Laser Characteri ation ( VI vs. Temperature)...30 B. Using L-V-I PLOT C. Analysis APPENDIX λ-s AN: AUT MATED WAVELENGTH SCAN...34 A. Device W velength Char cterisation (Spectral Characterisation)...34 B. Using WAVELENGTH S AN...35 APPENDIX DIS ERSION_TEST: FIBRE LENGTH & CHROMATIC DISPERSION MEASUREMENT SETUP...37 A. Modulation of lasers with an impulse response...37 B. Using DISPERSION TEST...37 REFERENCES...38