training_passive components_gb page 1 passive components september 2013

Training_Passive components_GB

Passive components

September 2013


Definition

Passive components are used to transmit signals to an end customer without integrating active components within a channel. Application: mainly in single mode Point to Multi-pointapplication.

Function• Light attenuation• Light filtering• Light coupling• Light splitting


Overview passive optical components

• Terminator• Attenuator• Coupler/Splitter • Multiplexer und de-multiplexer (WDM)

• Filter• Isolator• Passive dispersion compensator

• Connection• Splice• Fiber


Coupler/Splitter and xWDM

ONT: Optical Network Termination Street cabinet (FTTC) Apartment (FTTH)

Splitters: Splitting in blocks, Street, building

WDM: Multiplexer e.g. Triple Play1490nm,1310nm + 1550nm

OLT: Optical Line Termination (im CO)

Attenuator, Terminator: everywhere where fibers are unused


AttenuatorTerminator


Attenuator

Application• Adaption of the transmitted light power to the dynamic

range of the receiver.• Prevention of over amplification of the receiver• Installation between adapter and patch cord

Metal doped fiber

Pin Pout


Attenuations (SM)

Characteristics• Balancing the channel power in wave division

multiplexing system• Variable- and fixed value attenuatiors

male-side

female-side


Terminator

Characteristic• Limitation of return loss on open and unused

connector/adapter • Reduction of reflected light thanks to doped fiber in

terminator.• Prevention of disturb signal by reflected light

metal doped fiber

Pin

optical power converted in heat.


Terminator

Application• unused channels in telecommunication distribution

panels• measuring devices • CATV installations, in order to have a stable and lower

back reflection in the system.


Einsatz von Terminator (SM)

Open connectors in an installation:Open PC (0°) polished connector generates a RL of 14.7 dB (~ 3.5 % of optical power is reflected back)

causing damage:• in lasers• amplifiers• and other active components Terminator prevents back scattering from open ports.

Terminator (open end)

CouplerTransmitter

(Laser, amplifier)

Receiver


Splitter/Coupler/WDM - General

2011


Coupler/Splitter/WDM

Principle• splitting and coupling of optical signals• Power- or wavelength depending (WDM)

Requirements• Low insertion loss• high cross talk - and return loss• high insulation• small dimension• high thermal and mechanical stability

xWDMSplitter


Technologies

Various technologies are available for the coupler and splitter designs:

Splitter WDM

Fiber-based - Fused biconic tapered (FBT) fiber

Fiber-based - Fused biconic tapered (FBT) fiber

Waveguides based on planar lightwave circuit (PLC)

Thin-film filter (TFF)

Gratings

Bulk optical (BOG)

•Fiber Bragg (FBG)

Splitters can be packaged in different shapes and sizes, depending on the basic technology used.


Technologies

varied production methodology for splitter and coupler:

Fiber based• Fused biconic tapered (FBT)

Wafer based• Planar lightwave circuit (PLC)

Form of packing and size depending on production method


Technology and structure

Planar lightwave circuit (PLC) Silicon substrateoptical circuittypically high split counts (1x64)

Fused biconical taper (FBT) fiber coupler thermally fusedtypically low counts (1x4)

100%

Cut off

50%

50%


Naming of coupler/splitter based on arrangement

Structure

1x2 Y-coupler

2x2 X-coupler

1xN tree coupler

MxN star coupler

Structure of splitter and coupler


Variants 1x2, 2x2, 1x4, 2x4, 4x4…..2x128.Splitter are commonly cascaded with 1x2 or 2x2 splitter

Coupler/Splitter

Differences of splitter types varies on production method resp. further characteristics such as attenuation, uniformity etc.


Configuration and platform


Splitter and coupler

2011


Splitter

Splitter

Coupler = Splitter ≠ xWDM

1310nm+1550nm

17dBm/50mW

1310nm+1550nm

13.5dBm/22.5mW

1310nm+1550nm

13.5dBm/22.5mW

3dB+0.5dB

(3dB=50%)

Function• Splitting and coupling of optical signal• Power division


FBT - Fused Biconical Taper

When twisting and fusing two fibers at the same time a coupling zone gets generated.

One fiber is so called the reference fiber while the second one gets twisted around until the desired coupling ratio is achieved.

P0 P1

P2P3

Input Thoughput

CoupledCrosstalktappered tapperedcoupling


FBT - Fused Biconical Taper

Criteria Characteristic

Wavelength 1 or 2 wave length with restricted tolerance band

typical 1310+1550nm ±40nm

Dimension large

spliced

size 5 - 10cm

Attenuation up to a splitting ration 1x8 both types are similar

Price 1x2 ~ €10

Coupler Box

1x2

50/50Splice

Input


PLC - Planar Lightwave Circuit

P1Input

P2

P3

P4

P8

Ribbon or single fiber get s attached to the wafer. These fibers are meant to be assembled (connector) or spliced.

The power split is ensured by Y-junction (Ion-exchange) fabricated inside the bulk material using photolithography technique

Si Substrate

CladdingCore

Si Substrate

CladdingCore Mat.

Si Substrate

Cladding Mat.

Si Substrate

Cladding Mat.

Cladding Mat.

Maske

Ätzen


PLC - Planar Lightwave Circuit

Criteria Characteristic

Wavelength all optical (SM) windows

Dimension small

cascading on waver

size from 10-20mm

Attenuation far better than FBT

Price 1x2 ~ €30-40 (from 1x8 cheaper)

1x250/50

Fiber Arrays

Input


Terms we should know

Directivity: Amount of reflected light in the parallel running fiber on the same side caused by the splitter [dB]

Insertion loss: Loss in the splitter due signal splitting and splice losses [dB]

Return loss: Amount of light reflected at the connector as well as in the splitter [dB]

Uniformity: Difference of the highest attenuation at all split fibers at all wavelength [dB]

Polarization Depending Loss : max. allowed variation in dependency of the polarization of the coupled light [dB]


xWDM

2011


xWDM

xWDM

1310nm+1550nm

17dBm/50mW (pro λ)

1310nm

16dBm/40mW (pro λ)

1550nm

16dBm/40mW (pro λ)

1dB

Coupler = Splitter ≠ xWDM

Function• Splitting and coupling of optical signal• Wavelength division


Function BWDM / CWDM / DWDM

the principle of a fist class WDM‘s is according to the physical principle of light refraction.

• The longer a wave (λ) the less the refraction.• Therefore all kind of WDM’s contain an element to split

colors/frequencies.• this principle works with some little exception

bidirectional.


Function BWDM / CWDM / DWDM


xWDM - terms

BWDM Broad Wavelength Division Multiplexing

CWDM Coarse Wavelength Division MultiplexApplication: Metropolitan Area Network

DWDM Dense Wavelength Division Multiplex Application: Wide- and Global Area Network

Generally there are three different types:

Other types such as Add/Drop WDM are application specific and based on the same technology


FBT - WDM / CWDM / DWDM

Fused Biconical Taper (FBT)Similar process as for coupler/splitter. Due to the different mode field diameter one wavelength couples out. unutilized the wavelength dependency on the mode field Ø by increasing the wavelength the mode Ø increases too.

Mode field Ø at 1550nm 10.3µm

Mode field Ø at 1310nm 9.5µm

Core Ø 8.3µm

Cladding Ø 125µm

• Low cost

• Low insertion loss

• Low isolation

• Broad passband


Thin Film Filters (TFF)TFF‘s are coated with multiple layers of material that is manufactured using an ion-assisted physical vapor deposition. Each layer contains the property of a different refractive index. Particular wavelength are reflected or transmitted.

TFF - WDM / CWDM / DWDM

• Low insertion loss

• High isolation

• Low PMD

• High Return Loss

• To a limited extent applicable for DWDM


Fiber Bragg Gratings (FBG)Based on the principles of diffraction and of optical interference. When a polychromatic light source impinges on a diffraction grating, each wavelength is diffracted at a different angle and therefore to a different point in space. Using a lens, these wavelengths can be focused onto individual fibers

FBG - WDM / CWDM / DWDM

• Under the first CWDM/DWDM

• High Insertion Loss

• High costs

• High dispersion


Arrayed waveguide gratings (AWGs)Based on diffraction principles. An AWG device consists of an array of curved-channel waveguides with a fixed difference in the path length between adjacent channels. The process results in different wavelengths having maximal interference at different locations, which correspond to the output ports.

AWG - WDM / CWDM / DWDM

• Narrow passband

• DWDM applicable

• Low dispersion

• High costs

• High PDL


Development of WDM Systems

BWDM 2 channels1310nm and 1550 nm

CWDM max. 18 channels20nm spacing 1 carrier / window

DWDM max. 20 - 40 channels100-200 GHz spacing 1 carrier / window

1310nm 1550nm

1310nm 1550nm

1310nm 1550nm


BWDM / CWDM / DWDM

BWDM: Multiplexing with 2 wavelength (mainly 1310nm/1550nm), also called WWDM (Wide WDM)

CWDM: Multiplexing up to 16 wavelengths (20nm channel spacing between 1260nm and 1650nm)

DWDM: Multiplexing up to 160 wavelengths (1.6nm [200GHz], 0.8nm [100GHz] and 0.4nm [50GHz] channel spacing)


Split in various wavelength (λ)– Multiplexing (MUX)

Principle BWDM / CWDM / DWDM

Combine various wavelength (λ) – Demultiplexing (DEMUX)

Multi-plexer

λ1

λ2

λ3

λ4

De-Multi-plexer

λ1

λ2

λ3

λ4

1 Link, nchannels

Fiber


Broad Wave Division Multiplexing

BWDM Standard channel plan• 2 wavelength• 1310nm und 1550nm

12

70

nm

16

10

nm

15

10

nm

15

70

nm

12

90

nm

13

10

nm

13

30

nm

13

50

nm

13

70

nm

13

90

nm

14

10

nm

14

30

nm

14

50

nm

14

70

nm

14

90

nm

15

30

nm

15

50

nm

15

90

nm

O-Band E-Band S-Band C-Band L-Band U-Band

16

50

nm

16

30

nm

16

70

nm


Course Wave Division Multiplexing

CWDM Standard channel plan• developed by Int. Telecommunications Union (ITU)• 20 nanometer spacing between channels• Starting at 1270nm and going thru 1610nm • 18 Channels

12

70

nm

16

10

nm

15

10

nm

15

70

nm

12

90

nm

13

10

nm

13

30

nm

13

50

nm

13

70

nm

13

90

nm

14

10

nm

14

30

nm

14

50

nm

14

70

nm

14

90

nm

15

30

nm

15

50

nm

15

90

nm


16

50

nm

16

30

nm

16

70

nm


CWDM - characteristicsCWDM Coarse Wavelength Division Multiplex

Frequency range 1310 - 1610

Frequency space 20nm

Number of Channel 18

Laser cost effectivethanks to rough frequency space

Filter cheap, simple

Data rate 10Gbit/s per channel

Optical amplifying from 70 km

Chromatic Dispersion from 10Gbit/s


DWDM Standard channel plan developed by the ITU• International Telecommunications Union• 400, 200, 100, and now 50 GHz spacing between

channels• Starting at 1530nm and going thru 1560nm

Dense Wave Division Multiplexing

12

70

nm

16

10

nm

15

10

nm

15

70

nm

12

90

nm

13

10

nm

13

30

nm

13

50

nm

13

70

nm

13

90

nm

14

10

nm

14

30

nm

14

50

nm

14

70

nm

14

90

nm

15

30

nm

15

50

nm

15

90

nm


16

50

nm

16

30

nm

16

70

nm


DWDM - characteristicsDWDM Dense Wavelength Division Multiplex

Frequency range 1530-1625nm (C or L-Band)

Frequency space 0.4 – 4.6nm

Laser temperature- and wavelength stabilities

Filter hochwertig

Data rate 10-100Gbit/s per channel for up to 80 respectively 160 channels

Optical amplifying after 80 - 200 km

el. data regeneration after 600 - 2000 km

chromatic Dispersion from 10Gbit/s

Polarizationmodedispersion from 40Gbit/s


WDM / CWDM / DWDM

Common types in our market environment:

• WDM 1310/1550nm (FBT or TFF) • 4 / 8 channel CWDM (TFF)• 4+1 channel Mux/deMux (TFF) 1490,1510, 1530,

1550nm+1310nm according ITU-T G.983.1 recommendation (2 reserve channels)

• 8+1 channel Mux/deMux 1490-1610nm+1310nm (TFF)


Pass-band: also called Pass channel wavelength. Spectrum of wavelength a WDM operates respectively is optimized. Pass-band ripple: Tolerance value of the attenuation variation within the pass-band.

Isolation: Indicates the amount of ‘wrong’ wavelength/frequency carried in the fiber. A WDM for 1310nm with 17dB isolation may carry up to ~2% of e.g. 1550nm.

Terms we should know


Single mode band

Band Description Wavelength range

O-Band Original 1260–1360 nm

E-Band Extended 1360–1460 nm

S-Band Short wavelength 1460–1530 nm

C-Band Conventional 1530–1565 nm

L-Band Long wavelength 1565–1625 nm

U-Band Ultralong wavelength 1625–1675 nm

training_passive components_gb page 1 passive components september 2013

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