Filtros fotónicos de radiofrecuencia

8/13/2019 Filtros fotnicos de radiofrecuencia

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1

Departamento de Comunicaciones

Curso de Doctorado

2004-2005

Aplicaciones de la Fotnica de

Microondas

Filtros fotnicos de radiofrecuencia

basados en dispositivos avanzados

Contents

Fundamental concepts

Filters operation

Implementations:

A little history

Filters based on a single source

Filters based on multiwavelength narrow sources

Filters based on broadband sources


2/17

2

Fundamental Concepts

=

=

=M

r

r

r

N

k

k

k

zb

zazH

1

0

1

)(

Transfer functions for RF fi lters

Filter

=

=N

k

kTtkhnh0

)(][)(

h[2]

0 2 3

h[0]h[1]h[3]

h[N]Time Impulse

a) If N is finite: Finite Impulse Response (FIR) filter =

=N

k

k

kzazH0

)(

b) If N is infinite: Infinite Impulse Response (IIR) filter

=

=N

r

Tjr

reaH0

)(

=

=N

r

r rTtath0

)()(

Tz =1

Filter Frequency Response

Fundamental ConceptsTransfer functions for RF filters

The filter transfer function is always periodic in the frequency domain

0 1 2 3 4 5 6-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

FSR

f(Ghz)fr1 fr2

fr0

-3dB

f

MSSR

FSR [Hz]: Free Spectral Range or Spectral period FSR=1/f [Hz]: 3 dB Resonance bandwidth (same for all resonance orders)Q factor: Quality factor Q=frk/f (depends on the resonance)F: Finesse: F=FSR/f (indepndent of the resonance)MSSR [dB]: Main to secondary sidelobe ratio

Resonance

order 0Resonance

order 1

Resonance

order 2


3/17

3


Transfer functions for RF fi lters

modulator

InputRF Signal

CW laserSource

T

2T

NT

ao1/2

aN1/2

a21/2

Input electric field

Output electric field

receiver

Output RF Signal

Delay line weight

Opticalsignaltapping

element

Opticalsignalcombining

element

( )tsi

( ) ( )[ ] ( ) ( )( )rTtrTtwjir

erTtsatE + = 0

21

0

( )[ ] ( )( )ttwji

oets +21

( ) ( ) ( ) == rTtsatEts ir2

00

Signal taps

Optical delay lines

Optical weights

Signal combination

(couplers, stars, etc.)

General Layout

Source coherence

Polarization

Positive coefficients

Limited Spectral period or FSR (Free Spectral Range)

Noise

Reconfigurability

Tunability

Practical realization of RF filters



4/17

4

Fundamental ConceptsRequired photonics components

1) Optical signal tapping: Lasers, sliced broadband

sources, FBGs

2) Optical signal weighting:

3) Optical delay lines:

4) Optical signal combiners and switches

EDFAs, SOAs, EOMs, EAMs,

VCs, VOAS

Standard and HD fiber coils, LC-FBGs


Example: 3 tap transversal filter using fiber Coil delay lines

CW

optical

source1x3

T

2T

ao

a1

a2

3x1

=

=2

0

)()(r

r rTtxaty

Possible

optical

interference

(coherence)

RF signal

RF modulated

optical signalDelayed &Weighted

optical signals

Delayed &Weighted

RF signals


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5

CW

optical

source

CW

optical

source

CW

optical

source

RF signal

Dispersiveelement

to

to+T

to+2T

PossibleOptical

interference

(coherence )

Delayed &Weighted

optical signals

T

=

=2

0

)()(r

r rTtxaty

Delayed &Weighted

RF signalsPo

P1

P2Weighted

Optical

signals


Example: 3 tap transversal filter using Dispersive Delay Line

Filter Operation

The possibility to tune the RF bandpass position in a

sufficiently fast way either discretely or continuously

To tune the RF response of the filter, the FSR has to be

modified and therefore also the basic time delay T between

samples or taps.

Filter Tunability

0 1 2 3 4 5 6-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

FSR2

f(Ghz)fr1fr0

FSR1


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6

Filter Operation

A number of techniques to produce true time delays T

have been proposed:

Switched propagation paths (switched delay lines): Different

paths providing different basic propagation delays (that is

different values of T) can be chosen by means of an optical

space switch. It allows only step by step tunability, with the

tuning speed being limited by the switching time (1-10ms).

Wavelength tuning of one or multiple sources combined with

dispersive optical devices: based on tuneable sources anddispersive devices (Standard Fibre, High dispersive (dispersion

compensating) fibre, Linearly Chirped Fibre Bragg Gratings

(LCFBG)).Can provide continuous or step tunability at high

speed, limited by the tuning speed of the sources (depending on

the tuneable source technology from 100ns to >100ms).

Filter Tunability

A number of techniques to produce true time

delays T have been proposed:

Fixed wavelength multiple sources or sliced broad-

band sources combined with tuneable dispersive

devices: Based on novel devices and tuneabledispersion properties as Special Chirped FBGs with

actuators to change their dispersion properties. It can

provide continuous and step tunability but in this case

the time and accuracy to perform a dispersion change

on the fibre device is not so well controlled (100 ms-

1s).

Filter Operation

Filter Tunability


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7

Brings the possibility of changing dynamically the values

of the filter taps (ak, br coefficients) to reshape its

spectral response:

The windowing / weighting or apodisation of the

amplitude of the filter taps is also a fundamental aspect

to ensure enough rejection of the avoided bands.

Different apodisation functions have been demonstrated

for MSLR improvement:

By adjusting the power of the optical sources

By controlling the attenuation/gain suffered by the taps when

they travel though the optical processor

Filter Operation

Filter Reconfigurability

Implementations: a little historyFiber optic delay lines for microwave signal processing

Optical fiber as a delay medium for signal processing applications was proposed by Wilner

and van den Heuvel (1976).

Ohlhaber and Wilner (1977) reported an experimental demonstration of an optical fiber

transversal filter based on three multimode fiber delay paths to generate and correlate a 4-

bit, 88-Mb/s coded sequence.

An optical fiber frequency filter was demonstrated by Chang, Cassaboom, and Taylor

(1977), who illuminated a bundle of fifteen multimode fibers that provided fifteen different

delays spaced by 5.2 ns yielding a filter with a transfer function having a fundamentalpassband at 193 MHz.

Optical fiber as a delay medium for signal processing applications was proposed by Wilner

and van den Heuvel (1976).

Ohlhaber and Wilner (1977) reported an experimental demonstration of an optical fiber

transversal filter based on three multimode fiber delay paths to generate and correlate a 4-

bit, 88-Mb/s coded sequence.

An optical fiber frequency filter was demonstrated by Chang, Cassaboom, and Taylor

(1977), who illuminated a bundle of fifteen multimode fibers that provided fifteen different

delays spaced by 5.2 ns yielding a filter with a transfer function having a fundamentalpassband at 193 MHz.

K.P.Jackson et al., IEEE Trans. MTT, 33, pp. 193-210 (1985)

Implementation of single-mode fiber delay-line networks capable of synthesizing many

sophisticated time- and frequency-domain filtering operations (tapping mechanisms, basic

signal processing, etc.)

Implementation of single-mode fiber delay-line networks capable of synthesizing many

sophisticated time- and frequency-domain filtering operations (tapping mechanisms, basic

signal processing, etc.)

FSR=740 MHz


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8

A lit tle history

Wavelength tunable

fiber laser3 dB

coupler

Digitizing

oscilloscope

Signal

generatorDetector

1 m 1 m 1 m 1 m 1 m

G1 G6G2 G3 G4 G5

Ball et al, PTL pp.741-743 (1994)

Fiber-grating-based optical processors

50 ns true time delay in discrete 10 ns intervals

Grating spacing set to yield the desired delay

50 ns true time delay in discrete 10 ns intervals

Grating spacing set to yield the desired delay

LiNO3Modulator

Implementations

Laser

Polarization

controller

couplerTemperature

controller

Chirped fibre

gratingOptical receiver

MZ-EOM

Fibre delay line

Network analyser

Tunable RF transversal filters by using chirped FBGs

Zhang et al.,EL, pp. 1770-1772 (1998)

Linear and continuous tuning.

The time delay introduced by the grating is wavelength dependent.

Linear and continuous tuning.

The time delay introduced by the grating is wavelength dependent.


Implementations


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9

Tunable laser

LCA OC

1x8

splitter

attenuator

4

1 4

...

1 4

l1 l4

Tunable bandpass transversal filters

Zhang et al.,EL, pp.

1708-1710 (2000)

Changing the wavelength of the tunable laser selects operating gratings

Each grating array gives a filtering frequency

Possibility of designing the filter response (Hamming window)

A Mach-Zehnder section doubles the number of taps (so does Q factor)

Changing the wavelength of the tunable laser selects operating gratings

Each grating array gives a filtering frequency

Possibility of designing the filter response (Hamming window)

A Mach-Zehnder section doubles the number of taps (so does Q factor)


Implementations

Laser Recirculatingdelay line

Polarization

controller

MZ EOM

Optical Power

Meter

LCA

1

42 3

1

32

4

RF

Notch filter by using an optical fiber recirculating line

Zhang et al., IEEE MWCL, pp. 217-219 (2001)

The frequency response is controlled by the coupling coefficient of the

coupler and the length of the recirculating loop.

The fiber grating array enables to get a tunable FSR.

Continuous tunability can be achieved by using a chirped fiber grating

The frequency response is controlled by the coupling coefficient of the

coupler and the length of the recirculating loop.

The fiber grating array enables to get a tunable FSR.

Continuous tunability can be achieved by using a chirped fiber grating

IIR (Infinite Impulse Response filters)


Implementations


10/17

10

Filters based on multiwavelength narrow sources

Tunable source 3

Tunable source 4

DFB laser Vectorial

Network

Analyser

5x1Coupler

2x2Coupler

Fiber Grating

Adapted

Terminals

Electro-Optical

Modulator

Tunable source 1

Tunable source 2

Sample amplitudes are controlled by

laser output powers (reconfigurability)

The basic delay T is set by the spectral separation ofadjacent wavelengths. Thus T can be changed(tunability)

The linear chirp provides avariable delay with wavelength:

Each sample is carried using adifferent wavelength (=0.533nm)

1547 1548 1549 1550 1551-40

-30

-20

-10

0

0

1

2

3

4

Reflectivity(dB)

GroupDelay(ns)

N 2k

Wavelength (nm)

01

Tunable and reconfigurable filter based on a laser array and a LCFBG

0 1 2 3 4 5 6-5 0

-4 5

-4 0

-3 5

-3 0

-2 5

-2 0

-1 5

-1 0

-5

0

Frequency (GHz)

Modulus(dB)

Experimental resultTheoretical result

2.125 GHz

12dB

D. Pastor, J. Capmany and B. Ortega, OFC99 (1999)

Implementations

APODISATION

By the proper weighting of the tap

contributions controlling the output power

of the lasers in the array, the secondary to

main lobe ratio can be increased.

The figure shows a Gaussian apodisationas (0.5 0.8 1 0.8 0.5) that reduces the main

to secondary sidelobe ratio up to -20 dB.

APODISATION

By the proper weighting of the tap

contributions controlling the output power

of the lasers in the array, the secondary tomain lobe ratio can be increased.

The figure shows a Gaussian apodisationas (0.5 0.8 1 0.8 0.5) that reduces the main

to secondary sidelobe ratio up to -20 dB.

Filters based on multiwavelength narrow sourcesTunable and reconfigurable filter based on a laser array and a LCFBG

RECONFIGURABILITY

0 1 2 3 4 5 6-60

-50

-40

-30

-20

-10

0

0 1 2 3 4 6-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

5

Frequency (GHz)

Modulus(dB)

Experimental resultTheoretical result

Frequency (GHz)

Modulus(dB)

4 Taps 3 Taps

Laser 5 is switched off Laser 1 and 5 are switched off

By switching off one

or more lasers.

Bandpass positions

are maintained.

0-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

1 1.5 2 2.5 3 3.5 40.50.5 3.5

Frequency (GHz)

Modulus(dB)

No apodisedtaps

Gaussian Apodised tapsTheoretical apodised filter

Implementations


11/17

11

By adjusting of spectral spacing between sources to 0.266 nm (half of theprevious) the resonance separation increases up to 4.25GHz.

The figure shows results extended up to 10 GHz, and the CSE is observed. Thefirst notch is at 8.5 GHz for the dispersion parameter of the grating.

By adjusting of spectral spacing between sources to 0.266 nm (half of theprevious) the resonance separation increases up to 4.25GHz.

The figure shows results extended up to 10 GHz, and the CSE is observed. The

first notch is at 8.5 GHz for the dispersion parameter of the grating.

Carrier Suppression

Effect

The third main lobe is

just cancelled with this

particular parameters.

0 2 4 6 8 10-4 5

-4 0

-3 5

-3 0

-2 5

-2 0

-1 5

-1 0

-5

0

Frequency (GHz)

Modulus(dB)

Experimental result

Theoretical result

4.25 GHz

To overcome the CSE SSB

modulation was employed and

operation up to 20GHz with 3

taps was demonstrated.

To overcome the CSE SSB

modulation was employed and

operation up to 20GHz with 3

taps was demonstrated.

Filters based on multiwavelength narrow sourcesTunable and reconfigurable filter based on a laser array and a LCFBG

TUNABILITY

D. Pastor and J. Capmany, EL 34, pp 1684-1685 (1998)

Implementations

MAGNETIC TUNABLE

CHIRP DEVICE

Multiwavelengthsource

EOMCirculator

Uniform FBG

Network

Analyser

I

3A 0.39nm 916ps/nm

5A 0.56nm 475ps/nm

Curren t Bandwid th Delay s lope

Filters based on multiwavelength narrow sourcesMultiwavelength source with tunable chirped grating

-25

-20

-15

-10

-5

0

REFLECTIVITY(dB)

1 54 4. 4 1 54 4.7 15 45. 0 1 54 5. 3 1 54 5. 6

0

125

250

375

500

DELAYTIME(ps)

WAVELENGTH (nm)

0 2 4 6 80

20

4060

80

100

5 A

3 A

AXIAL DISTANCE (cm)

Coil

Uniform Bragg Grating Magnetostrictive

Rod

MAGNETIC FIELD -25

-20

-15

-10

-5

0

REFLECTIVITY(dB)

-25

-20

-15

-10

-5

0

REFLECTIVITY(dB)

0 3 6 9 12 15

-25

-20

-15

-10

-5

0

REFLECTIVITY(dB)

FREQUENCY (GHz)

6.36GHz

8.14GHz

9.39GHz

0 A

2 A

4 ACONTINUOUSTUNABILITY

CONTINUOUS

TUNABILITY

Implementations


12/17

12

(b)

MultiwavelengthSource EOM

z axis

Coils

TFBG

RF input

(a)

Out toLCA (bar)

Out toLCA(cross)

I1

LCA

I2Y-junction Coupler

Optical

switch

z axis

1542 1543 1544 1545

-40

-30

-20

-10

(nm)

Reflectivity(dBm)

0.2

0.4

0.6

0.8

Group

DelayTime(ns)

(a)

MagneticField

0 1 2 3 4

4

6

8

10

12

14

FSR(

GHz)

I (A)

1543 15440.0

0.5

1.0 BS

CS(ns)

(nm)

0 2 4 6 8 10

-30

-20

-10

0 (b)

H(

dB)

f (GHz)

-30

-20

-10

0 (a)

H(

dB)

SWITCHED DELAY LINESWITCHED DELAY LINESWITCHED DELAY LINE

LARGER

TUNABILITY

LARGER

TUNABILITY

Filters based on multiwavelength narrow sourcesMultiwavelength source with tunable chirped grating

(ps/nm) 0 A 2 A 4 A

BAR 351 297 230

CROSS 715 580 420

(ps/nm) 0 A 2 A 4 A

BA R 351 297 230

CROSS 715 580 420J. Mora et al., EL, 39, p. 1799-1800 (2003)

Implementations

Filters based on multiwavelength narrow sourcesCurrent Injection in multimode lasers

Fabry- Perot

Lasernear

the threshold

current

Isolator

EOM EDFA

Dispersiveelement.

46 km SSMF

Receiver

RF Network

AnalyserIbias Input

1540 1542 1544 1546 1548 1550 1552 1554 15560

20

40

60

80

100

120

140

Wavelength (nm)

LinearArbitraryUnits

A Fabry-Perot laser was employed toprovide a CW multi-wavelength source

The entire optical signal is RF modulated

and applied to a dispersive media (46 km

SSMF).

The bias current of the FP laser was

controlled near the threshold to providedifferent weighing profiles and thereforealso different MSLR and 3dB BW values.

Increasing the

Bias current

D.Pastor, et al. IEEE Photon. Tech. Lett., vol. 13, pp. 1224-1226, (2001)

0 1 2 3 4 5 6-3 5

-3 0

-2 5

-2 0

-1 5

-1 0

-5

0

Frecuency (GHz)

|H(f)|dB

Frequency (GHz)

Implementations


13/17

13

Filters based on broadband sourcesBragg grating based acousto-optic superlattice modulator

(a)

0 1 2 3 4 5 60.0

0.5

1.0

1.5

Wavelength

shift(nm)

fs(MHz)

0,0 0,5 1,0 1,5 2,0

0,00

0,25

0,50

0,75

1,00

Reflectivity(dB)

PS(mW)

(b)

1542 1543 1544-70

-60

-50

-40

R(

dB)

(nm)

-70

-60

-50

-40

R(

dB)

0 5 10 15 20

-45

-30

-15

0

|H|2

(dB)

f (GHz)

-45

-30

-15

0

|H|2

(dB)

The interaction between a longitudinal acoustic

wave and a strong FBG can generate a fiberBragg grating array suitable for RF applications.

Tunability and reconfigurability of the device are

demonstrated.

The interaction between a longitudinal acousticwave and a strong FBG can generate a fiberBragg grating array suitable for RF applications.

Tunability and reconfigurability of the device are

demonstrated.

EOM

Tap

Power

Wavelength

Broadband

Source

90/10

Coupler

10

90

Wavelength

Group

Delay

Time

Tapping

Element

OSA

LCA

fiber

length

Optical

Power

Wavelength

Broadband

Source

Horn

Transducer

RF supply-2 -1 0 1 2-20

-10

0

Reflectivity(dB)

-B/

-20

-10

0

Reflectivity(dB) (a)

(b)

Tapered

fiber

FBG

Circulator

M.Delgado-Pinar et al., MWP04

Implementations

Multitap filter using in-fiber Bragg grating arrays

Spectral slicing of a broadband source

Bragg gratings equispaced in time

Possibility of designing the filter response (Kaiser window)

Spectral slicing of a broadband source

Bragg gratings equispaced in time

Possibility of designing the filter response (Kaiser window)

Hunter et al.,IEEE MGWL, pp. 103-105 (1996)

Grating sets3 dB couplerElectro-optic

modulator

Network analyser and

display

RF oscillator

1480nm

pump

diode

IsolatorWDM

15m Erbium

doped fiber

Photodetector


Implementations


14/17

14

Filters based on broadband sourcesLED sliced by tunable gratings

Electro-optic modulatorOSAOSA

23 kmfiber

SLED

1L2

EDFAEDFA

LCALCA

UFBGs

90-10 Coupler

RF signal

Mechanical stageReflected signals

2

3

0

glue

1545 15460.0

0.5

1.0

R(a.u.)

(nm)

( ) NeinitN

LLpN

= 1

,LNN

NLLN

=

0 50 100 150

1545

1546

1547

1548

1549 3

2

1

0

N(nm)

L (m)

0.0 0.5 1.0 1.5 2.0 2.50

1

2

3

4

5

6

FSR(GHz)

-1(nm-1)

J. Mora et al., Opt. Express10, 1291-1298 (2002).

Implementations

Mechanical stage

0

L2

UFBGs4x4 coupler

AT

Variable

attenuator

3

2

1

From LED

Reflected signals

To modulator

glue

-3 -2 -1 0 1 2 3-30

-25

-20

-15

-10

-5

P(a.u.)

P(a.u.)

MSLR(dB)

AT

(dB)

-3 0

-2 0

-1 0

0

H(dB)

-3 0

-2 0

-1 0

0

H(dB)

0 2 4 6 8 1 0

-3 0

-2 0

-1 0

0

f (GHz)

H(dB)

(a)

(b)

(c)

Sidelobe Supressed Filters

Filters based on broadband sourcesLED sliced by tunable gratings

Implementations


15/17

15

D. Pastor et al, Opt. Lett. 2003, 28, pp. 18021804.

SLED

EDFA

1X40

AWG

1X40

AWG EOM

Network

Analyser

SOA 23 kmSSMF

1 540 1 54 5 1 55 0 1 55 5 15 60 1 56 5-40

-38

-36

-34

-32

-30

-28

-26

-24

-22

-20

Wavelength(nm)

Amplitude(dB)

Array of:

SwitchesVariable

attenuators.

Broadband Source sliced by AWGs Two Combined BB sources arespectrally sliced by means of a pair of

Arrayed Waveguide Gratings (AWGs)

AWG are standard ITU for DWDMapplic (0.8 nm channel spacing and

0.4nm channel BW)

Switches and/or Variable attenuatorsbetween AWGs provides weighing andtuneability features.

A dispersive media (SSMF) is used to

imprint the proper time delay to eachslice (sample) after the modulation of

the RF signal over the entire spectrum

at the EOM

12 slices (channels)

spaced 2 x 0.8 nm = 1.6 nmUniform weighing

Dispersive Med: 400ps/nm

RF response: FSR=1.56 GHz3dB B W=125 MHz

MSLR=15 dB0 2 4 6 8 10-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

Frequency (GHz)

Amplitude(dB)

1 .1 1 .2 1 .3 1 .4 1 .5 1 .6 1 .7 1 .8 1 .9 2

-30

-25

-20

-15

-10

-5

0

Frequency(GHz)

Amplitude(dB)

0 Hz lobe out

of measure

>130MHz


Implementations

1 2 3 4 5 6 7 8 9 10-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

Frequency (GHz)

Amplitude(dB)

1540 1550 1560Wavelength(nm)

1 2 3 4 5 6 7 8 9 10-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

Frequency (GHz)

Amplitude(dB)

1540 1545 1550 1555 1560 1565Wavelength(nm)

24 slices (channels)spaced 0.8 nm

Uniform weighing (aprox)

Dispersive Med: 400ps/nmRF response: FSR=3.1 GHz

3dB BW=125 MHz (aprox)

MSLR=14 dB

6 slices (channels)

spaced 4 x 0.8 nm = 3.2 nmApodized samples

Dispersive Med: 400ps/nmRF response: FSR= 780 MHz

3dB B W=200 MHzMSLR=15 dB (with half samples

as previous)

Examples of Tuneability and Apodization


Broadband Source sliced by AWGs

Implementations


16/17

16

Practical Limits

Intrinsic to the Slicing approach:1. Spectral power inefficiency if the ratio

SliceBW / SliceSpacing is low or/and theBandwidth of the BB source is larger than

slices range.2. RF decaying envelope due to the low pass

filtering effect produced by the Slicebandwidth and the dispersive media.

We can appreciate in the simulation as the

product (GVD) determinates the 3dBbandwidth of the decaying slope in RF

domain.

(1) and (2) move in opposite directions

Extrinsic to the Slicing approach:

1. Precise amplitude control of each tap was

difficult due to the PDL of the AWG and EOM(mainliy the EOM) devices in combination witha polarized source like it was the SLED.

Filters based on broadband sourcesBroadband Source sliced by AWGs

Implementations

A single bandpass RF filter based on a MZI illuminated with a

broadband source.

A tuning range of several tens of GHz is achieved by changing

the optical paths of the MZI and the dispersion.

The bandwidth of the RF filter is kept constant along the RF

range, when the dispersion in the system is invariant.

Potential high Q values can be achieved by choosing the

appropriate broadband source.

A single bandpass RF filter based on a MZI illuminated with a

broadband source.

A tuning range of several tens of GHz is achieved by changing

the optical paths of the MZI and the dispersion.

The bandwidth of the RF filter is kept constant along the RF

range, when the dispersion in the system is invariant.

Potential high Q values can be achieved by choosing the

appropriate broadband source.

Filters based on broadband sourcesBroadband source sliced by a MZI

J. Mora et al., Intl. Topical Meeting on MWP, pp. 251-254 (2003).

Implementations


17/17

EDFA 1

1

FABRY-PEROTFILTER

Electro-Optical

Modulator70 km SSMF

EDFA 2

vectorial

networkanalyser

0 1 2 3 4 5 6-60

-50

-40

-30

-20

-10

0

Frequency (GHz)

NormalisedModulus

ofH(f),dB

1526 1528 1530 1532 1534 1536 15380

20

40

60

80

1526 1528 1530 1532 1534 1536 15380

0.5

1

)(nm

)(nm

Normalised

Weights

OpticalPower

(arbitrarynaturalunits) (a)

(b)

(a)-(b)

A fibre based Fabry-Perot filter of 35 GHz

of FSR and high Finesse was employed toslice the 1530 nm peak of ASE noise from

an EDFA. Almost 35 naturally aposized resonances(samples) can be distinguished over the

noise floor at the receiver input.

3dB BW=250MHz

>35dB

J. Capmany, et. al. Electron. Lett., pp. 494-496, (1999).

Filters based on broadband sourcesBroadband source sliced by Fabry-Perot

Implementations

Documents

Filtros fotónicos de radiofrecuencia