Fiber-Optic Measurement Techniques

Front Cover
Fiber-Optic Measurement Techniques
Copyright
Contents
Preface to first edition
Preface to the second edition
Chapter 1: Fundamentals of optical devices
1.1. Introduction
1.2. Laser diodes and LEDs
1.2.1. Pn junction and energy diagram
1.2.2. Direct and indirect semiconductors
1.2.3. Carrier confinement
1.2.4. Spontaneous emission and stimulated emission
1.2.5. Light-emitting diodes (LEDs)
1.2.5.1. PI curve
1.2.5.2. Modulation dynamics
1.2.6. Laser diodes (LDs)
1.2.6.1. Rate equations
1.2.6.2. Steady state solutions of rate equations
1.2.6.3. Threshold carrier density
Threshold current density
PJ relationship about threshold
Side-mode suppression ratio (SMR)
Turn-on delay
Small-signal modulation response
Laser noises
Relative intensity noise (RIN)
Phase noise
Mode partition noise
1.2.7. Single-frequency semiconductor lasers
1.2.7.1. DFB laser diode
1.2.7.2. External cavity laser diode
1.2.7.3. Integrated tunable lasers
1.3. Photodetectors
1.3.1. Pn-junction photodiodes
1.3.2. Responsivity and bandwidth
1.3.3. Electrical characteristics of a photodiode
1.3.4. Photodetector noise and SNR
1.3.4.1. Noise-equivalent power (NEP)
1.3.5. Avalanche photodiodes (APDs)
1.3.6. APD used as single photon detectors
1.4. Optical fibers
1.4.1. Reflection and refraction
1.4.1.1. Fresnel reflection coefficients
1.4.1.2. Special cases
Normal incidence
Critical angle
1.4.1.3. Optical field phase shift between the incident and the reflected beams
1.4.1.4. Brewster angle (total transmission ρ=0)
1.4.2. Propagation modes in optical fibers
1.4.2.1. Geometric optics analysis
1.4.2.2. Mode analysis using electromagnetic field theory
1.4.2.3. Numerical aperture
1.4.3. Optical fiber attenuation
1.4.4. Group velocity and dispersion
1.4.4.1. Phase velocity and group velocity
1.4.4.2. Group velocity dispersion
1.4.4.3. Sources of chromatic dispersion
1.4.4.4. Modal dispersion
1.4.4.5. Polarization mode dispersion (PMD)
1.4.5. Nonlinear effects in an optical fiber
1.4.5.1. Stimulated Brillouin scattering
1.4.5.2. Stimulated Raman scattering
1.4.5.3. Kerr effect nonlinearity and nonlinear Schrödinger equation
1.5. Optical amplifiers
1.5.1. Optical gain, gain bandwidth, and saturation
1.5.2. Semiconductor optical amplifiers
1.5.2.1. Steady-state analysis
1.5.2.2. Gain dynamics of OSA
Optical wavelength conversion using cross-gain saturation
Wavelength conversion using FWM in SOA
Optical phase modulation in an SOA
1.5.3. Erbium-doped fiber amplifiers (EDFAs)
1.5.3.1. Absorption and emission cross sections
1.5.3.2. Rate equations
1.5.3.3. EDFA design considerations
Forward pumping and backward pumping
EDFAs with AGC and APC
1.5.3.4. EDFA gain flattening
1.5.4. Raman amplification in optical fiber
1.6. External electro-optic modulator
1.6.1. Basic operation principle of electro-optic modulators
1.6.2. Frequency doubling and duobinary modulation
1.6.3. Optical single-side modulation
1.6.4. I/Q modulation of complex optical field
1.6.5. Bias point stabilization of an I/Q modulator
1.6.6. Optical modulators using electro-absorption effect
References
Chapter 2: Basic mechanisms and instrumentation for optical measurement
2.1. Introduction
2.2. Grating-based optical spectrum analyzers
2.2.1. General specifications
2.2.2. Fundamentals of diffraction gratings
2.2.2.1. Measure the diffraction angle spreading when the input only has a single frequency
2.2.2.2. Sweep the signal wavelength while measuring the output at a fixed diffraction angle
2.2.3. Basic OSA configurations
2.2.3.1. OSA based on a double monochromator
2.2.3.2. OSA with polarization sensitivity compensation
2.2.3.3. Consideration of focusing optics
2.2.3.4. Optical spectral meter using photodiode array
2.3. Scanning FP interferometer
2.3.1. Basic FPI configuration and transfer function
2.3.1.1. Free spectral range (FSR)
2.3.1.2. Half-power bandwidth (HPBW)
2.3.1.3. Finesse
2.3.1.4. Contrast
2.3.2. Scanning FPI spectrum analyzer
2.3.3. Scanning FPI basic optical configurations
2.3.4. Optical spectrum analyzer using the combination of grating and FPI
2.4. Mach-Zehnder interferometers
2.4.1. Transfer matrix of a 2x2 optical coupler
2.4.2. Transfer function of an MZI
2.4.3. MZI used as an optical filter
2.5. Michelson interferometers
2.5.1. Operating principle of a Michelson interferometer
2.5.2. Measurement and characterization of Michelson interferometers
2.5.3. Sagnac loop mirror
2.6. Optical wavelength meter
2.6.1. Operating principle of a wavelength meter based on Michelson interferometer
2.6.2. Wavelength coverage and spectral resolution
2.6.2.1. Wavelength coverage
2.6.2.2. Spectral resolution
2.6.2.3. Effect of signal coherence length
2.6.3. Wavelength calibration
2.6.4. Wavelength meter based on Fizeau wedge interferometer
2.7. Optical ring resonators and their applications
2.7.1. Ring resonator power transfer function and Q-factor
2.7.2. Ring resonators as tunable optical filters
2.7.3. Label-free biosensors based on high-Q ring resonators
2.7.4. Electro-optic modulators based on ring resonators
2.8. Optical polarimeter
2.8.1. General description of lightwave polarization
2.8.2. The stokes parameters and the Poincare sphere
2.8.3. Optical polarimeters
2.9. Measurement based on coherent optical detection
2.9.1. Operating principle
2.9.2. Receiver SNR calculation of coherent detection
2.9.2.1. Heterodyne and homodyne detection
2.9.2.2. Signal-to-noise ratio in coherent detection receivers
2.9.3. Balanced coherent detection and polarization diversity
2.9.4. Phase diversity in coherent homodyne detection
2.9.5. Coherent OSA based on swept frequency laser
2.10. Waveform measurement
2.10.1. Oscilloscope operating principle
2.10.2. Digital sampling oscilloscopes
2.10.3. High speed real-time digital analyzer
2.10.4. High-speed sampling of optical signal
2.10.4.1. Nonlinear optical sampling
2.10.4.2. Linear optical sampling
2.10.4.3. Sampling oscilloscope base on single-photon detection
2.10.4.4. High-speed electric ADC using optical techniques
2.10.5. Short optical pulse measurement using an autocorrelator
2.11. LIDAR and OCT
2.11.1. Light detection and ranging (LIDAR)
2.11.1.1. Pulsed LIDAR with direct detection
2.11.1.2. FMCW LIDAR and pulse compression
2.11.2. OCT
2.12. Optical network analyzer
2.12.1. S-Parameters and RF network analyzer
2.12.2. Optical network analyzers
2.12.2.1. Scalar optical network analyzer
2.12.2.2. Vector optical network analyzer
References
Chapter 3: Characterization of optical devices
3.1. Introduction
3.2. Characterization of RIN, linewidth, and phase noise of semiconductor lasers
3.2.1. Measurement of relative intensity noise (RIN)
3.2.2. Measurement of laser linewidth and phase noise
3.2.2.1. Self-homodyne and self-heterodyne detection
3.2.2.2. Coherent envelope detection and complex optical field detection
3.2.2.3. Non-Lorentzian phase noise and Lorentzian-equivalent linewidth
3.2.3. Multi-heterodyne technique to characterize spectral properties of semiconductor laser frequency combs
3.3. Measurement of electro-optic modulation response
3.3.1. Characterization of intensity modulation response
3.3.1.1. Frequency-domain characterization
3.3.1.2. Time-domain characterization
3.3.2. Measurement of frequency chirp
3.3.2.1. Modulation spectral measurement
3.3.2.2. Measurement utilizing fiber dispersion
3.3.3. Time-domain measurement of modulation-induced chirp
3.4. Wideband characterization of an optical receiver
3.4.1. Characterization of photodetector responsivity and linearity
3.4.2. Frequency domain characterization of photodetector response
3.4.3. Photodetector bandwidth characterization using source spontaneous-spontaneous beat noise
3.4.4. Photodetector characterization using short optical pulses
3.5. Characterization of optical amplifiers
3.5.1. Measurement of amplifier optical gain
3.5.2. Measurement of static and dynamic gain tilt
3.5.2.1. Static gain tilt
3.5.2.2. Dynamic gain tilt
3.5.3. Optical amplifier noise
3.5.4. Optical domain characterization of ASE noise
3.5.5. Impact of ASE noise in electrical domain
3.5.5.1. Signal-spontaneous emission beat noise
3.5.5.2. Spontaneous-spontaneous beat noise spectral density
3.5.6. Noise figure definition and its measurement
3.5.6.1. Noise figure definition
3.5.6.2. Optical domain measurement of noise figure
3.5.6.3. Electrical domain characterization of a noise figure
3.5.7. Time-domain characteristics of EDFA
3.5.8. Characterization of fiber Raman amplification
3.5.8.1. Noise characteristics of Raman amplifiers
3.5.8.2. Forward/backward hybrid pumping and 2nd-order pumping
3.5.8.3. RIN transfer from the pump to the optical signal
3.5.8.4. Characterization of fiber Raman amplifiers
3.6. Characterization of passive optical components
3.6.1. Fiber-optic couplers
3.6.2. Fiber Bragg grating filters
3.6.3. WDM multiplexers and demultiplexers
3.6.3.1. Thin film-based interference filters
3.6.3.2. Arrayed waveguide gratings
3.6.4. Characterization of optical filter transfer functions
3.6.4.1. Modulation phase-shift technique
3.6.4.2. Interferometer technique
3.6.5. Optical isolators and circulators
3.6.5.1. Optical isolators
3.6.5.2. Optical circulators
References
Chapter 4: Optical fiber measurement
4.1. Introduction
4.2. Classification of fiber types
4.2.1. Standard optical fibers for transmission
4.2.2. Specialty optical fibers
4.3. Measurement of fiber mode-field distribution
4.3.1. Near-field, far-field, and mode-field diameter
4.3.2. Far-field measurement techniques
4.3.3. Near-field measurement techniques
4.4. Fiber attenuation measurement and OTDR
4.4.1. Cutback technique
4.4.2. Optical time-domain reflectometers
4.4.3. Improvement considerations of OTDR
4.5. Fiber dispersion measurements
4.5.1. Intermodal dispersion and its measurement
4.5.1.1. Pulse distortion method
4.5.1.2. Frequency-domain measurement
4.5.2. Chromatic dispersion and its measurement
4.5.2.1. Modulation phase shift method
4.5.2.2. Baseband AM response method
4.5.2.3. Interferometric method
4.6. Polarization mode dispersion (PMD) measurement
4.6.1. Representation fiber birefringence and PMD parameter
4.6.2. Pulse delay method
4.6.3. The Interferometric method
4.6.4. Poincare arc method
4.6.5. Fixed analyzer method
4.6.6. The Jones Matrix method
4.6.7. The Mueller Matrix method
4.7. Determination of polarization-dependent loss
4.8. PMD sources and emulators
4.9. Measurement of fiber non-linearity
4.9.1. Measurement of stimulated Brillouin scattering coefficient
4.9.2. Measurement of the stimulated Raman scattering coefficient
4.9.3. Measurement of Kerr effect non-linearity
4.9.3.1. Non-linear index measurement using SPM
4.9.3.2. Non-linear index measurement using FWM
4.9.3.3. Non-linear index measurement using cross-phase modulation
4.9.3.4. Non-linear index measurement using modulation instability
References
Chapter 5: Fiber-based optical metrology and spectroscopy techniques
5.1. Introduction
5.2. Discrete fiber-optic sensors
5.2.1. Fiber-optic sensors based on optical path loss
5.2.2. Fiber-optic sensors based on interferometry
5.2.3. Fiber-optic sensors based on Faraday rotation of polarization
5.2.4. Fiber-optic gyroscopes
5.2.5. Fiber-optic sensors based on fiber Bragg gratings
5.2.6. Fiber-optic sensors based on Fabry-Perot interferometers
5.3. Distributed fiber sensors
5.3.1. Phase-sensitive OTDR
5.3.2. Brillouin and Raman OTDR
5.3.2.1. Measurements based on Brillouin scattering
5.3.2.2. Measurements based on Raman scattering
5.3.3. Interferometer-based distributed fiber sensors
5.4. Optical frequency combs and their applications
5.4.1. Basic definitions of optical frequency comb parameters
5.4.2. Femtosecond fiber lasers
5.4.3. Frequency stabilization of optical frequency combs
5.4.4. Precision metrology based on optical frequency combs
5.4.5. Measurements based on coherent dual combs
5.5. Nonlinear spectroscopy and microscopy based on femtosecond fiber lasers
5.5.1. Soliton self-frequency shift and generation of λ-tunable femtosecond pulses
5.5.2. Two-photon fluorescence microscopy based on λ-switchable femtosecond pulses excitation
5.5.3. CRS spectroscopy based on λ-tunable femtosecond pulses excitation
5.5.4. CRS microscopy based on λ-tunable femtosecond pulses excitation
References
Chapter 6: Optical system performance measurements
6.1. Introduction
6.2. Overview of fiber-optic transmission systems
6.2.1. Optical system performance considerations
6.2.2. Receiver BER and Q
6.2.3. System Q estimation based on eye diagram parameterization
6.2.4. Bit error rate testing
6.2.4.1. Pattern generator
6.2.4.2. Error detection
6.3. Receiver sensitivity measurement and OSNR tolerance
6.3.1. Receiver sensitivity and power margin
6.3.2. OSNR margin and required OSNR (R-OSNR)
6.3.3. BER versus decision threshold measurement
6.3.4. EVM and BER for high order complex modulation
6.4. Waveform distortion measurements
6.5. Jitter measurement
6.5.1. Basic jitter parameters and definitions
6.5.2. Jitter detection techniques
6.5.2.1. Jitter measurement based on sampling oscilloscope
6.5.2.2. Jitter measurement based on a phase detector
6.5.2.3. Jitter measurement based on a BER-T scan
6.6. In situ monitoring of linear propagation impairments
6.6.1. In situ monitoring of chromatic dispersion
6.6.2. In situ PMD monitoring
6.6.2.1. Basic operating principle
6.6.2.2. PMD monitoring using coherent detection
6.6.2.3. Difference between fiber DGD and the DGD experienced by an optical signal
6.6.3. In situ PDL monitoring
6.7. Measurement of non-linear crosstalks in WDM systems
6.7.1. Cross-phase modulation and pump-probe based measurement techniques
6.7.1.1. Measure XPM-induced phase modulation
6.7.1.2. Measure XPM-induced intensity modulation
6.7.1.3. Characterization of electrostriction non-linearity based on coherent detection
6.7.2. FWM-induced crosstalk in optical systems
6.7.3. Create WDM crosstalk channels with spectrally shaped broadband Gaussian noise
6.8. Optical performance monitoring based on coherent optical transceivers
6.8.1. Estimating system OSNR with a digital coherent transceiver
6.8.2. Measuring non-linear phase shift in a fiber-optic system with a digital coherent transceiver
6.8.2.1. Measurement using a single transceiver
6.8.2.2. Multi-span measurements with a recirculating loop and a separate coherent receiver
6.9. Optical system performance evaluation based on required OSNR
6.9.1. Measurement of R-SNR due to chromatic dispersion
6.9.2. Measurement of R-SNR due to fiber non-linearity
6.9.3. Measurement of R-OSNR due to optical filter misalignment
6.10. Fiber-optic recirculating loop
6.10.1. Operation principle of a recirculating loop
6.10.2. Measurement procedure and time control
6.10.3. Optical gain adjustment in the loop
References
Chapter 7: Measurement errors
7.1. Introduction
7.1.1. Error classification and reporting
7.2. Measurement error statistics
7.2.1. Effective sample size in the presence of serial correlations
7.3. Central limit theorem (CLT)
7.3.1. Approximations related to the central limit theorem
7.4. Identifying candidate outliers
7.5. Error estimates of measurement combinations
7.5.1. Error estimates for combinations of uncorrelated measurement samples
7.5.2. The weighted mean
7.6. Linear least squares fitting of data
7.6.1. Fitting evaluation based on a chi-square merit function
7.6.2. A fitting example
References
Index
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