L3 OPTICAL FIBER DEVICES

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L3OPTICAL FIBER DEVICES COMPONENT PASSIVE
ACTIVE

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The Whole View
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OPTICAL NETWORK
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Industrial Communication
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Unit Multiplier
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Unit Of Measurement

• Decibel (dB/dBm)
• To express gain or loss in the system
• dB 10 Log10 (Pout/ Pin)

Pin
System/components
Pout
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dB Table
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dBm decibels reference to 1 milliwatt
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dB mW table
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Wavelength Spacing
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Wavelength vs Frequency
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Wavelength
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Wavelength (cont.)
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CWDM vs DWDM
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Optical Transmission Spectrum
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PASSIVE VS ACTIVE

• Active need external power (ELECTRICITY) to
  perform
• Passive no external power required

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Part I Optical Passive Devices
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Optical Couplers

• Couplers can perform both combining and
  splitting.
• The devices are widely used in optical LAN and
  broadcasting networks

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Optical Couplers

• An optical coupler is a passive (unpowered)
  device that diverges (1N) or converges (N1)
  optical signals from one fibre or optical signal
  path to more than one (or vice versa.)
• Configurations Splitters, taps, combiners,
  directional couplers

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Optical Couplers Fabrication Techniques

• Fusion
• Most popular type of coupler
• Fiber based
• Mass-produced
• Mechanical
• Earlier technique
• Optics based
• Fussy
• Mask and etch
• Growing in popularity
• Future technology
• - Waveguide based

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Optical Couplers Characteristics

• COUPLING RATIO

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Optical Couplers

• EXCESS LOSS
• Ratio of the input power to the total output power

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Optical Couplers

• INSERTION LOSS

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Optical Couplers

• DIRECTIVITY

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Couplers - Fabrication
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ISOLATORS
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ISOLATOR SPECIFICATION
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Couplers and Isolator in Optical Amplifiers
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CIRCULATORS
Optical circulators redirects light
sequentially from port-to-port in a
unidirectional path
Same characteristics as isolators by looking port
1-2 _at_ port 2-3
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CIRCULATORS

• Characteristics
• high isolation
• low insertion loss
• can have more than 3 ports

• Applications
• Optical Amplifier
• Add-Drop Multiplexer
• Bi-directional transmission
• To monitor back-reflection from devices or
  optical subsystems

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CIRCULATORS APPLICATION
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Fiber Bragg Gratings
A grating is a periodic structure or perturbation
in a material that creates a property of
reflecting or transmitting light in a
certain direction depending on the wavelength.
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Bragg Gratings - testing
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Fiber Bragg Gratings
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Fiber Bragg Gratings

• Characteristics
• high reflectivity to be used as a filter
• low insertion loss
• low cost/simple packaging

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Fiber Bragg Gratings

• Transmission spectrum
• band-rejection filter

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Fiber Bragg Gratings

• Reflection spectrum
• reflective filter

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FBG APPLICATIONS
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FBG APPLICATIONS
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FBG APPLICATIONS
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FIBER BRAGG GRATING SPECS.
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ATTENUATORS
Function To decrease light intensity (power)
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ATTENUATORS

• Characteristics
• low insertion loss
• dynamic attenuation range
• wide range of operating wavelength
• high return loss

• Applications
• adjust optical power to the dynamic range of
  receivers
• equalize power between different WDM signals
• To avoid receiver saturation

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ATTENUATORS
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ATTENUATORS
Programmable attenuator
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Optical Fibre Connectors
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Optical Fibre Connectors
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Part II. Optical Active Devices

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TX - RX
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Light Sources

• 2 types
• Semiconductor Lasers
• Fabry Perot Laser Diode (FP)
• Light Emitting Diode (LED)
• Distributed Feedback Laser Diode (DFB)
• VCsel laser
• Fibre Lasers
• Ring Lasers

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Light Emitting Diode
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Fabry Perot Laser Diode
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Distributed Feedback Laser Diode
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Fibre Lasers

• _at_1530nm _at_1550nm

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COMPARISON OF LIGHT SOURCES
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Transceiver modules(TX and RX in the same
package) widely used in the optical routing and
switching equipment
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Detector/Receiver

• Opposite function from the light source
  converts optical energy to electrical energy.

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Signal detect
Signal detect output
Quantizer
Pre-Amp
Signal output
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Detector/Receiver Specification

• Receiver sensitivity the weakest optical signal
  that can be received
• Dynamic Range different between minimum and
  maximum power level
• Data rate/bandwidth
• Operating wavelength
• Responsivity (A/W)
• Jitter/Duty cycle

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Photodetectors

• Responsivity

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Erbium-doped Fibre Amplifier
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Important Parameter in EDFA

• Gain, G (dB)
• 10log(PSignal_Out - Pase) / PSignal_In
• Noise Figure, F
• SNRout / SNRin
• S-band 1440 - 1530nm
• C-band 1530 - 1565nm
• L-band 1565 - 1625nm

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Typical Application of EDFA
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Component/Device Testing Requirement

• Optical Power Meter
• Optical Light Source
• Optical Attenuator
• Fusion Splicer machine
• Optical connector/adaptors
• Optical Spectrum Analyser(OSA)
• Tunable laser source

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Thank You