This teaching material is a part of e-Photon/ONe Master study
in Optical Communications and Networks
Course and module:
Photonics in Switching
Optical components
Author(s):
Lena Wosinska, Bo Willen
Royal Institute of Technology KTH
Lena.Wosinska@imit.kth.se
No part of this presentation can be reused without the permission of author(s).
Users are requested to ask for permission by specifying the purpose of the usage.
http://www.e-photonone.org
Optical Components
•
•
•
•
•
•
•
•
Couplers
Isolators and Circulators
Filters
Multiplexers and Demultiplexers
Amplifiers
Transmitters and Receivers
Switches
Wavelength converters
Revision: date
2( )
Couplers
α
1-α
Revision: date
3( )
Couplers
 ( )  sin(  )
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4( )
Couplers
Key parameters
•
•
•
•
Excess loss
α(ℓ)-variations
Wavelength dependence
Polarisation dependence
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5( )
Couplers
cos() i sin()  Ei1( f )
 Eo1( f )
 i 

 e 


 Eo2 ( f )
 i sin() cos()   Ei 2 ( f )
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6( )
Couplers
cos() i sin()  Ei1( f )
 Eo1( f )
 i 

 e 


 Eo2 ( f )
 i sin() cos()   Ei 2 ( f )
 cos2 (κ) sin 2 (κ) 

T   2
2
 sin (κ) cos (κ) 
 T11 ( f )   ½ 

   
 T12 ( f )   ½ 
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7( )
Isolators and circulators
• Need: Avoid backward travelling waves,
sometimes detrimental for laser performance.
• Problems: Expensive and bulky


One of the remaining problems in optical networks:
Small, integrated devices are needed,
Magnetic fields required since we are dealing with
non-reciprocal devices.
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8( )
Isolators and circulators
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9( )
Isolators and circulators
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10 ( )
Isolators
and
Circulators
• Nonreciprocal
• Key parameters


Insertion loss ~ 1 dB
Isolation ~ 40-50 dB
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11 ( )
Isolators
Principle of operation
~
~
~
~
E(r, t )  Exeˆx  Eyeˆy  Ezeˆz
Two polarisation modes: Vertical and horisontal.
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12 ( )
Isolator
Revision: date
13 ( )
Polarisation independent
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14 ( )
Isolator
Polarisation independent
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15 ( )
Multiplexers and Filters
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16 ( )
Filters
Key parameters
• Insertion loss
• State of polarisation
dependence
• Temperature coefficient
• Passband flatness
• Crosstalk suppression
• Cost
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17 ( )
Gratings
• Bulk, fiber, waveguide…
a
Imaging plane
qi
qd
Grating equation
m
sin(q d )  sin(qi ) 
a
 q d depends on wavelength
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18 ( )
Blazed Gratings
α = blaze angel
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19 ( )
Stimax Grating
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20 ( )
Bragg Gratings
• Fiber gratings
• Long period fiber gratings
• Waveguide gratings
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21 ( )
Bragg Gratings
• Bragg phase-matching condition:
• Bragg wavelength:
2eff
 1  0 
0
2
 0  1 

0  2eff 
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22 ( )
Bragg gratings
Efficiency    tanh2 (L); L  length;  couplingcoefficient

1
Fractionalbandwidth 

B Number of " participating" fringes
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23 ( )
Fiber Bragg Gratings
•
•
•
•
•
Low loss
Low crosstalk
Ease of coupling
Polarization insensitive
Low temperature
coefficient
• Simple packaging
• The index of refraction
increases in UV-light.
• Short-period ~ 0.5 µm
• Long-period ~ 100 µm
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24 ( )
Long-period Fiber Grating
  eff 
p
eff
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25 ( )

A Bragg grating directional coupler OADM
1
Spatial separation of drop
No losses for add channel
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26 ( )
Bragg grating OADM
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27 ( )
Fabry-Perot Filters
Mirrors
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28 ( )
Thin-Film Filters
Cavity
Dielectric
reflectors
Cavity
Glass substrate
A resonant multi-cavity thin-film filter.
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29 ( )
Multilayer dielectric thin film filters
Key parameters:
• Flat top of the passband
• Sharp skirts
• Temperature insensitive
• Low loss
• Polarisation insensitive
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30 ( )
Semiconductor Waveguides
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31 ( )
Mach-Zehnder Interferometer
Non-linear element varying the time delay.
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32 ( )
Mach Zehnder Interferometer
Add/drop function
L. Wosinski, M. Swillo and M. Dainese, “Imprinting of low dispersion Bragg gratings in
planar devices for 40 Gbps DWDM systems”, Proc. of International Congress on Optics
and Optoelectronics, Warsaw, Poland 28 August - 2 September 2005, Proc. SPIE 5956,
pp OD1 – OD8.
Revision: date
33 ( )
AWG or Phasar
•
•
•
•
•
•
•
•
Number of channels
Central frequency
Channel spacing
Bandwidth
Insertion loss
Crosstalk
Polarisation dependence
Temperature dependence
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34 ( )
Advanced devices by PECVD in silica-on-silicon
State-of-the-art devices in PECVD technology are dense WDM
MULTI/DEMULTIPLEXERS by Arrayed-Waveguide Grating (AWG)
used to combine or divide narrowly spaced channels
Characteristics
AWG configuration
AWG fabrication
32 output channels, 0.8 nm channel spacing
(100 GHz), 25 nm band
L. Wosinski,“ Silica-on-Silicon Technology for Photonic Integrated Devices”,
6th International Conference on Transparent Optical Networks, Wroclaw,
Poland, Julyl 4 - 8, 2004, Proceedings of the IEEE, vol. 2, pp 274 - 279.
Revision: date
Laboratory of
35 ( )
PHOT ONICS
and
MICROWAVE Eng.
Add/Drop multiplexer
Bragg grating assisted MMI-coupler based add/drop-multiplexer
Input access
waveguide
Adiabatic taper
section
Bragg grating
section
Drop output
access waveguide
Transmission output
access waveguide
0
Transmission (dB)
Transmission (dB)
0
-10
-20
-30
-40
-1
-2
-50
-60
1540
1545
1550
1555
Wavelength (nm)
1560
-3
1548
1549
1550
1551
Wavelength (nm)
L. Wosinski, M. Dainese, H. Fernando and T. Augustsson, “Grating-assisted
add-drop multiplexer realized in silica-on-silicon technology”, Proceedings of
Revision: date
the Conference “Photonics Fabrication Europe”, Brugge, Belgium, 28
October, 1 November 2002, Proc. SPIE 4941, pp 43-50.
36 ( )
1552
AWG Cross Connect
 , , ,
1
1
1
2
1
3
1
4
 , , ,
1
1
Revision: date
2
2
37 ( )
3
3
4
4
Amplifiers
• Regenerators
• Clock recovery
• Erbium-Doped Fibre
Amplifiers
• Raman amplifiers
• Semiconductor Optical
Amplifiers
•
•
•
•
•
Scalability
Analogue devices
Noise accumulation
Bandwidth
Gain Flatness
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38 ( )
Optical Amplifiers
•
•
•
•
Stimulated emission
Spontaneous Emission
Polarisation dependence
Crosstalk




Gain
Noise
Amplitude fluctuations
Noise
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39 ( )
EDFA
Gain flattening filters
B- and C-band EDFA’s in parallel
C-band: Higher Erbium doping or longer
(Raman)
1460
1530
S-band
1565
1610 1625
L-band
C-band
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40 ( )
EDFA
•
•
•
•
Polarisation independent
No crosstalk
Wide wavelength range
Transparent
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41 ( )
EDFA, Gain Flattening
• Fluoride doped fiber
• Noise, pumped @ 1480
• Filter
• Power loss
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42 ( )
Raman. Nonlinear effects
• Stimulated Raman
• Phonon scattering
• Four-wave mixing
• Refractive index
modulation
Revision: date
43 ( )
Raman. Stokes wave
•
•
•
•
Pump power lost to phonons
Pump wavelength < Stokes wavelength
Noise – backward pump
Crosstalk
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44 ( )
Semiconductor Optical Amplifiers
• Transparent amplifier
• Wavelength converter
• Optical switch
• A forward biased p/n-junction
• AR-coating to avoid lasing
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45 ( )
Semiconductor Optical Amplifiers
•
•
•
•
•
•
Bandwidth ~100 nm (1.3 – 1.55µm)
Crosstalk
Coupling loss
Polarization dependence
Noise
High-quality AR-coating - FP
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46 ( )
Transmitters
• Lasers
• External Modulators (EA, MZI, ...)


High-frequency modulation
Low chirp
• Light emitting diodes



Low-frequency modulation
Broad band
Low power
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47 ( )
Lasers
•
•
•
•
•
•
•
•
Output power
Threshold current
Slope efficiency
Operation wavelength
Spectral width
Side-mode suppression
Wavelength stability
Dispersion
•
•
•
•
•
•
•
FP-lasers
DFB-lasers
DBR-lasers
External cavity
VCSEL
Tunable lasers
Mode-locked lasers
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48 ( )
Detectors
•
•
•
•
pin-diodes
Avalanche diodes, APD
msm-diodes
Front-end amplifiers


• Bandwidth
• Noise
• Dynamic range
High-impedance
Transimpedance
Revision: date
49 ( )