Features

• EDFA System enables student to experimentally investigate the principles and characteristics of EDFA in C Band ( 1530nm – 1565 nm)
• Demonstrates amplification of 1550 nm wavelength along with the detection and measurement of amplified signal.
• Investigation and Analysis of Small and Large Signal Gain
• Facility to implement Forward and Backward Pumping and Study Gain Characteristics

Edfa block diagram

• 1550nm signal and 980nm pumped inside EDF
• 2:1 WDM system is used to combine pump and optical signal (1550nm)
• The Erbium atoms absorb 980nm pump signal and jump to higher energy state
• 1550nm strikes excited Er+3 ions and initiate Stimulated Emission
• 1550nm amplified by stimulated emission

Amplification principle

• Figure above describe the energy level diagram for Er+3 ion
• 1480 nm pump excites Er+3 to quasi metastable stage
• Coincidently, emits wavelengths in the range 1525- 1565nm range while returning back to ground state fromquasi-metastable stage
• This amplifies the signal by stimulated emission.

Specifications
Lasers @1550nm

• 1.25 Gbps Laser Diode Module at wavelength of 1550nm
• In Built Isolator
• Channel Spacing    : 20 nm
• Threshold Current Ith    : 10 mA Typical
• Output Power    : @ Ith + 30 mA - > 0.7 mW @ ~ 58 mA-> 1.4 mW
• Operating Voltage    : 1.1V Typical

PUMP LASER@980nm

• Up to 100 / 150mW Uncooled 980nm Pump Module
• Maximum Operating Power : 100 / 150mW
• Maximum Operating Current : 340mA
• Center Wavelength    : Min 970nm Max 980nm
• Optical Connector    : SC/PC

Optical Detector

• 1.5 GHz InGaAs PIN Photodiode Module.
• Responsivity    : Typical 0.9 A/Win 9/125 μmfiber
• Spectral Range    : 1250nm to 1600nm
• Reverse Voltage    : 30 V max.
• Optical Connector    : SC/PC

Wavelength Division Multiplexer

• Operating Wavelength(nm) : 980/1550
• Max. Insertion Loss (dB)    : 0.20
• Isolation (dB)    : >20
• Polarization Sensitivity(dB) : <0.05

Erbium doped fiber

• The core of the fiber is doped with Erbium.
• In EDF fiber core acts as gain medium or Host
• MFD (Nominal)    : 5.5 - 6.3um@1550nm
• Core NA    : 0.21 - 0.24
• Cut - off Wavelength : 900 - 940nm
• C-Band Single Mode Fiber (1530 - 1565nm)
• Peak Absorption    : 4.5-5.5 dB/m@980nm; : 5.4-7.1 dB/m@1531nm

Optical filter

• An optical filter is a device that selectively transmits light of different wavelengths, usually implemented as a glass plane or plastic device in the optical path, which are either dyed in the bulk or have interference coatings.
• Center Wavelength    : 1550nm@ 2nm BW
• Pass bandwidth @0.5dB    : 2.0nm
• Return Loss    : ≥ 50dB

Variable attenuator

• An optical attenuator, or fiber optic attenuator, is a device used to reduce the power level of an optical signal
• The power reduction is done by such means as absorption, reflection, diffusion, scattering, deflection, diffraction, and dispersion, etc. optical attenuators usually work by absorbing the light.
• Attenuation Range : 0.8 to 60dB
• Wavelength : 1550nm

Software

• User friendly GUI for monitoring, controlling of EDFA system
• Operating modes like CW mode, VI characteristics mode, Internal & External Modulation
• LASER control like Supply ON/OFF, wavelength selection and driving current selection.
• Real time signal level monitoring of Photo-detector.
• Graphical representation : XY plot of VI characteristics and Internal Modulation
• COM Settings : USB 2.0

Software interface

1.    Vi characterisation of pump and lasersource

• Above picture shows the VI characteristics of pump and source LASER.
• VI characteristics of both LASERs could be observed in the software by selecting VI characteristics in the Operating Mode option.

2.    Laser controls

• Individual LASER voltage can be controlled using slider provided in software
• LASER voltage and corresponding LASER current is displayed on the screen

3.    Modulation mode

• LASER voltage controls provided
• Select LASER on Left column
• Internal and External modulation options available
• 4 Modulation frequencies(100Hz, 200Hz,500Hz,1KHz) can be used
• Modulated signals displayed on graph in right column

4.    Optical spectrum analyzer display

• Output Spectrum of EDF with Signal Source (1550nm)

Accessories

• Shielded USB A-A cable    : 01No
• Power Cable    : 01No
• SC-SC Single Mode Fiber    : 06No
• Optic Patch Chords
• BNC to BNC coaxial cable    : 01No
• Software on CD    : 01No
• FTDI Drivers
• Experimental Manual    : 01No