Fiber-Optic Measurement Techniques

Chapter 1: Fundamentals of optical devices

• • 1.1, Laser diodes and LEDs
• • 1.1.1, pn junction and energy diagram
• • 1.1.2, Direct and indirect semiconductors
• • 1.1.3, Carrier confinement
• • 1.1.4, Spontaneous emission and stimulated emission
• • 1.1.5, Light Emitting Diodes (LED)
• • 1.1.6, Laser Diodes (LD)
• • 1.1.7, Single frequency semiconductor lasers
• • 1.1.8, Integrated tunable lasers (ITLA)
• • 1.2, Photo-detectors
• • 1.2.1, PN-junction photodiodes
• • 1.2.2, Responsivity and bandwidth
• • 1.2.3, Electrical Characteristics of a photodiode
• • 1.2.4, Photo-detector noise and SNR
• • 1.2.5, Avalanche photodiodes (APD)
• • 1.2.6, Single-photon detectors
• • 1.3, Optical fibers
• • 1.3.1, Reflection and refraction
• • 1.3.2, Propagation modes in optical fibers
• • 1.3.3, Optical fiber attenuation
• • 1.3.4 Group velocity and dispersion
• • 1.3.5, Nonlinear effects in an optical fiber (add electrostriction within SBS)
• • 1.4, Optical amplifiers
• • 1.4.1, Optical gain, gain bandwidth and saturation
• • 1.4.2, Semiconductor optical amplifiers
• • 1.4.3, Erbium-doped fiber amplifiers (EDFA)
• • 1.4.4, Distributed Raman amplification
• • 1.5, External electro-optic modulator
• • 1.5.1, Basic operation principle of electro-optic modulators
• • 1.5.2 Frequency doubling and duo-binary modulation
• • 1.5.3 Optical single-side modulation
• • 1.5.4, Optical modulators using electro-absorption effect
• • 1.5.5, I/Q modulation of complex optical field

Chapter 2: Basic Instrumentation for Optical Measurement

• • 2.0 Introduction
• • 2.1 Grating-base optical spectrum analyzers
• • 2.1.1 General specifications
• • 2.1.2 Fundamentals of diffraction gratings
• • 2.1.3 Basic OSA configurations
• • 2.2 Scanning FP interferometer
• • 2.2.1 Basic FPI configuration and transfer function
• • 2.2.2 Scanning FPI spectrum analyzer
• • 2.2.3 Scanning FPI basic optical configurations
• • 2.2.4 Optical spectrum analyzer using the combination of grating and FPI
• • 2.3 Mach-zehnder interferometers
• • 2.3.1 Transfer matrix of a 2 x 2 optical coupler
• • 2.3.2 Transfer function of an MZI
• • 2.3.3 MZI used as an optical filter
• • 2.4 Michelson interferometers
• • 2.4.1 Operating principle of a Michelson interferometer
• • 2.4.2 Measurement and characterization of Michelson interferometers
• • 2.5 Optical wavelength meter
• • 2.5.1 Operating principle of a wavelength meter based on Michelson interferometer
• • 2.5.2 Wavelength coverage and spectral resolution
• • 2.5.3 Wavelength calibration
• • 2.5.4 Wavelength meter based on Fizeau wedge interferometer
• • 2.6 Optical ring resonators
• • 2.6.1 Ring resonator transfer function
• • 2.6.2 Techniques of increasing Q-values
• • 2.6.3 Applications of ring resonators
• • 2.6 Optical polarimeter
• • 2.6.1 General description of lightwave polarization
• • 2.6.2 The Stokes parameters and the Poincare sphere
• • 2.6.3 Optical polarimeters
• • 2.7 Measurement based on coherent optical detection
• • 2.7.1 Operating principle
• • 2.7.2 Receiver SNR calculation of coherent detection
• • 2.7.3 Balanced coherent detection and polarization diversity
• • 2.7.4 Phase diversity in coherent homodyne detection
• • 2.7.5 Coherent OSA based on swept frequency laser
• • 2.8 Waveform measurement
• • 2.8.1 Oscilloscope operating principle
• • 2.8.2 Digital sampling oscilloscopes
• • 2.8.3 High speed real-time digital analyzer
• • 2.8.3 High-speed sampling of optical signal
• • 2.8.4 High-speed electric ADC using optical techniques
• • 2.8.5 Oscilloscope base on single-photon detection
• • 2.8.6 Short optical pulse measurement using an autocorrelator
• • 2.9 Optical low-coherent interferometry → Optical Reflectometry
• • 2.9.1 Direct-detection LIDAR systems
• • 2.9.1 Optical low-coherence reflectometry
• • 2.9.2 Fourier-domain reflectometry (add: complex-field LIDAR)
• • 2.10 Optical network analyzer
• • 2.10.1 S-parameters and RF network analyzer
• • 2.10.2 Optical network analyzers

Chapter 3: Characterization of optical devices

• • 3.1, Characterization of RIN and linewidth of semiconductor lasers
• • 3.1.1, Measurement of relative intensity noise (RIN) (add normalization procedure)
• • 3.1.2, Measurement of laser phase noise, frequency-dependent FM noise, and linewidth
• • 3.2, Measurement of electro-optic modulation response
• • 3.2.1 Characterization of intensity modulation response
• • 3.2.2 Measurement of frequency chirp
• • 3.2.3 Time-domain measurement of modulation-induced chirp
• • 3.2.4 Bias point stabilization of an I/Q modulator
• • 3.3, Wide-band characterization of an optical receiver
• • 3.3.1, Characterization of photodetector responsivity and linearity
• • 3.3.2, Frequency domain characterization of photodetector response
• • 3.3.3, Photodetector bandwidth characterization using source spontaneous-spontaneous beat noise
• • 3.3.4, Photodetector characterization using short optical pulses
• • 3.3.5 Digital equalization of a optical transceiver transfer function (adaptive filter)
• • 3.4, Characterization of optical amplifiers
• • 3.4.1, Measurement of amplifier optical gain
• • 3.4.2, Measurement of static and dynamic gain tilt
• • 3.4.3, Optical amplifier noise
• • 3.4.4, Optical domain characterization of ASE noise
• • 3.4.5, Impact of ASE noise in electrical domain
• • 3.4.6, Noise Figure definition and its measurement
• • 3.4.7, Time domain characteristics of EDFA
• • 3.4.8, Distributed Raman amplification in fiber-optic systems
• • 3.5, Characterization of passive optical components
• • 3.5.1, Fiber-optic couplers
• • 3.5.2, Fiber Bragg-grating filters
• • 3.5.3, WDM multiplexers and demultiplers
• • 3.5.4, Optical isolators and circulators

Chapter 4: Optical fiber measurement

• • 4.1, Classification of fiber types (add: new fibers such as AllWave, TeraWave, ...)
• • 4.2, Measurement of fiber mode-field distribution
• • 4.2.1, Near-field, far-field and mode field diameter
• • 4.2.2 The far-field measurement techniques
• • 4.2.3 The near-field measurement techniques
• • 4.3, Fiber attenuation measurement, OTDR and OFDR
• • 4.3.1, Cutback technique
• • 4.3.2, Optical time-domain reflectometer
• • 4.3.3 Improvement considerations of OTDR
• • 4.3.4 OFDR: optical frequency domain reflectometry
• • 4.4, Fiber dispersion measurements
• • 4.4.1, Intermodal dispersion and its measurement
• • (1) Pulse distortion method
• • (2) Frequency domain measurement
• • 4.4.2, Chromatic dispersion and its measurement
• • (1) Modulation phase shift method
• • (2) Baseband AM response method
• • (3) Interferometric method
• • (4) Measurement with a digital coherent receiver
• • 4.5, Polarization Mode Dispersion (PMD) Measurement
• • 4.5.1, Representation fiber birefringence and PMD parameter:
• • 4.5.2, Pulse delay method
• • 4.5.3, The Interferometric method
• • 4.5.4, Poincare Arc Method:
• • 4.5.4, Fixed Analyzer Method
• • 4.5.6, The Jones-Matrix method
• • 4.5.7, The Mueller-Matrix method
• • 4.6, Determination of polarization-dependent loss
• • 4.7, PMD sources and emulators
• • 4.8, Measurement of fiber nonlinearity
• • 4.8.1, Measurement of Stimulated Brilliouin Scattering Coefficient
• • 4.8.2, Measurement of Stimulated Raman Scattering Coefficient
• • 4.8.3, Measurement of Kerr-effect nonlinearity

Chapter 5: Fiber-based optical sensors and spectroscopy techniques

• • 5.1, Overview of fiber-optic sensors
• • 5.2, Stress and temperature sensors based on fiber Bragg gratings
• • 5.3, Distributed fiber sensors based on Rayleigh and stimulated Brillion scattering
• • 5.4, Optical frequency combs and their applications
• • 5.4.1 Techniques to create optical frequency combs
• • 5.4.2 Precision metrology based optical frequency combs
• • 5.4.3 Dual-frequency combs and applications
• • 5.5, Nonlinear spectroscopy and microscopy based on femtosecond fiber lasers
• • 5.5.1 Femtosecond fiber lasers
• • 5.5.2 Soliton-self-frequency shift
• • 5.5.3 Two-photon microscopy based on fiber lasers
• • 5.5.4 CARS and SRS based on wavelength swept femtosecond pulses

Chapter 6: Optical system performance measurements

• • 6.1, Overview of fiber-optic transmission systems
• • 6.1.1, Optical system performance considerations
• • 6.1.2, Receiver BER and Q
• • 6.1.3, System Q estimation based on eye diagram parameterization
• • 6.1.4, Bit Error-rate Testing
• • 6.2, Receiver sensitivity measurement and OSNR tolerance
• • 6.2.1, Receiver sensitivity and power margin
• • 6.2.2, OSNR margin and required OSNR (R-OSNR)
• • 6.2.3, BER vs. decision threshold measurement
• • 6.3, Waveform distortion measurements
• • 6.4, Time jitter measurement
• • 6.4.1, Basic jitter parameters and definitions
• • 6.4.2 Jitter detection techniques
• • 6.5 In-situ monitoring techniques of fiber-optic systems
• • 6.5.1, In-situ monitoring of chromatic dispersion
• • 6.5.2, In-situ PMD monitoring
• • 6.5.3, In-situ PDL monitoring
• • 6.6, pump-probe measurements
• • 6.6 Pump-probe measurement techniques (XPM, FWM, Electrostriction)
• • 6.7 System degradation measurements based on the required OSNR
• • 7.7.1, Measurement of R-SNR due to chromatic dispersion
• • 7.7.2, Measurement of R-SNR due to fiber nonlinearity
• • 7.7.3, Measurement of R-SNR due to optical filter misalignment
• • 6.8 Optical system performance monitors based on integrated optical circuits
• • 6.9, Optical re-circulating loop
• • 7.9.1. Operation principle of a recirculating loop
• • 7.9.2. Measurement procedure and time control
• • 7.9.3. Optical gain adjustment in the loop

Chapter 7: Measurement uncertainty and error analysis

• • 7.1, Prologue
• • 7.2, Specification and measurement
• • Measurement standard types
• • absolute errors
• • secondary errors
• • 7.3. Sources of uncertainty in optical measurements
• • Systematic
• • Random
• • Guard bands
• • 7.4. Error statistics and aggregation
• • Error distributions of single and multiple sources
• • Central limit Theorem
• • Error calculus
• • Correlated and uncorrelated errors
• • 7.5. Reporting errors: Text and graphical
• • Functional extraction from measured data
• • Errors in extracted functional parameters
• • Linear system and Neural network examples