PHOTONIC DEVICES AND MODULES FOR DATA PROCESSING

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PHOTONIC DEVICES AND MODULES PHOTONIC DEVICES AND MODULES FOR DATA PROCESSING, ANALYZING FOR DATA PROCESSING, ANALYZING

AND MONITORING IN OPTICS AND MONITORING IN OPTICS COMMUNICATION LINKSCOMMUNICATION LINKS

Zeev Zalevsky

School of Engineering, Bar-Ilan University

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Outline•Processing & modulating

•Electro-optical •Photo-activated•All-optical

•Analyzing•Optical Viterbi decoder•RF photonic filters

•Monitoring•Conclusions

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•Analyzing•Optical Viterbi decoder

•RF photonic filters


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ElectroElectro--optical modulatorsoptical modulatorsZeev Zalevsky, Ofer Limon, Luca Businaro, Dan Cojoc and Annamaria Gerardino

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Operation PrincipleOperation Principle

•Nano metallic and charged particle is trapped in special hole generated in the silicon.•The walls of the hole care are coated with oxide.•External voltage may move the particle that is trapped in the capacitor.•When the particle is moved into the optical path of the IR beam, it creates scattering.•True nano dimensional transistor. •The small dimensions allow fast mechanical movements.•Power dissipation only at switching transients.

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500nm

210nm

80nm

200nm 640nm

200nm

150nm

180nmSi

SiO2

Air

500nm

210nm

80nm

200nm 640nm

200nm

150nm

180nmSi

SiO2

Air

Schematic sketch of the designed device.

Preliminary fabrication attempt.

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Particle up

- 4

- 1

Field

Intensity

Particle upParticle upParticle up

- 4

- 1

- 4

- 1

Field

Intensity

Particle down

- 4

- 1

Field

Intensity

Particle downParticle downParticle down

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- 1

- 4

- 1

Field

Intensity

Numerical investigation of the nano particle based modulator. (a). ON state of the device (the particle is away form the optical path). (b). OFF state of the device (the particle is inside the optical path and it generates scattering of light).

(a). (b).

Numerical simulations

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Advantages:Advantages:

•Partially optical, i.e. partially reduced noises, reduced RF design considerations at high frequencies etc.•Small wavelength sensitivity (no resonator).•No finesse, i.e. no latency to reach steady state.•Really nano-size device.•Low power consumption.•Operation rate is not limited by various electro-optical and non linear effects in silicon.•No power consumption at steady state.

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Disadvantages:Disadvantages:

•Currently, low extinction ratio (around 1:4).•Long term functionality (difficult to avoid discharging of the particle).•Difficult fabrication process.•Although the mechanical vibration rate is high (few GHz) it is yet not high enough.

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PhotoPhoto--activated modulatorsactivated modulatorsZeev Zalevsky, Doron Abraham, Avraham Chelly, Yossef Shappir, Michael Rosenbluh

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n+

n+

p+ p+

p-type

n-type

Si oxide

Vs

Vd

VgVg

p-type

x=0

n+ n+

VcVc

Simplified version of a SOSPET device in equilibrium. The contacts marked Vg, Vd and Vs are the Gate Drain and Source voltages in the device. The cross-hatched region represents the silicon oxide block.

Sketch of the depletion layers under the bias voltage. (a). Illumination is OFF, the data channel is open. (b). Illuminationis ON, the depletion layers close the data channel.

(a).

(b).

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•No illumination (open channel): •Si(p)-Ox-Si(n) junction’s depletion layers are generated on both sides of the tunnel. •Most of the depletion layer is at the p-type and the layer in n-type side is thin enough to keep channel open. •Increasing voltage pushes p-type into inversion state and the electrons are moved towards the insulation layer. •Sweep channel removes those electrons (no electrons are remaining in p-type area).

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Operation PrincipleOperation Principle-- cont.cont.

•No illumination (open channel): •Since the p-type charge is negative, the only way of doing that is by increasing the depletion layer. •The inversion state is not possible now due to lack of free electrons. •It works as MOS capacitor in its deep depletion state.

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•With illumination (closed channel): •The illumination on the p-type area creates pairs of holes and electrons. •The holes of the p-type recombine with the photo-activated electrons but yet the free electrons concentration at that illuminated p-type area is significantly increased.•The depletion layer at the p-type region is narrowed until it reaches the inversion state.•The depletion layer at the n-type area penetrates deeply into the channel.

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Operation PrincipleOperation Principle-- cont.cont.

•With illumination (closed channel): •The generated electrons are drifted to the positive contact trough the “sweep channel”.•The generation rate of the electrons at the illuminated area is much higher than the sweeping rate.•The p-type area is now at the inversion state, and not in deep depletion as before.• The electrons in the surface of the insulator (the inversion layer) are the "generated electrons".

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Energy- band diagram of the SOS junction, around of the oxide block. (a). Without illumination. The p-type is in deep depletion state. (b). With the illumination on the p-type area. The p-type is in inversion state.

(a).

(b).

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Laser

Wafer

MirrorF.D

Probe

The C-V measurement setup. The gate voltage Vg includes a staircase DC bias and the vg sinusoidal AC signal at frequency of 100 KHz. The voltmeter and the ampere meter measure the magnitude and phase of the voltage across the MOS capacitance and the current through it. The laser is the illumination source.

Picture of the C-V measurement setup.

Experimental results

Area=10-2 [cm2]Area=10-2 [cm2]Area=10-2 [cm2]

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The C-V measurements for dark and illuminated cases. The temperature remains all the time at room temperature at 300K. The wavelength of the illumination was λ=532[nm], The MOS was a p-type with acceptors density of NA=1014[cm-3].

The ratio between the total capacitance and the capacitance of the oxide versus time. The difference between the lines is the way how the illumination was done: The dashed line is without any illumination. The left one is with a short pulse illumination and the right line is with continuous illumination starting after the change in the voltage. The MOS was a p-type with acceptor density of NA=1014[cm-3] and the oxide capacitance is: Cox=370[pF]. The illumination power was about 0.5mW.


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Plot of the free electrons concentration, across the data channel. One can see that the difference between the two states is more than one order of magnitude.

One of the masks related to the fabrication process of the SOSPET device.

Numerical simulations

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•Partially optical, i.e. partially reduced noises, reduced RF design considerations at high frequencies etc.•The control is fast and has no RC related speed limitations.•The info is electronic i.e. no wavelength sensitivity and no finesse related latency.

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•Although fast, the operation rate is still limited by the drift of carriers in silicon.•The info is electronic and requires RF design considerations.•The size is small in comparison to optical devices but yet larger than micro electronic transistors.•It consumes power to keep the device closed.

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AllAll--optical modulatorsoptical modulatorsZeev Zalevsky, Ofer Limon, Menachem Nathan and Arkady Rudnitsky

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•Miniaturized MMI (Mach-Zehnder) interferometer.•The two optical arms are balanced.•Visible spatially non uniform illumination (speckles)generates free carriers in silicon.•Due to plasma dispersion effect the absorption and the relative phase of the two arms in the MMI is unequally varied.•Small misbalance of the two arms creates strong IR output.

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Numerical simulation

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0 50 100 150 200 250 300 350 400 450 500-6

-5

-4

-3

-2

-1

0

Time[μSec]

Abs

orpt

ion

%

I llumination power effect

1298 [mA]1009 [mA]808 [mA]662 [mA]528 [mA]400 [mA]

Image of the fabricated device.

Measurements of the effect of visible illumination power on the contrast of the modulation of the IR information beam (at 1546nm). The current supplied to the visible Nd:YAG laser is in [mA]. 400mA is the minimal current required to obtain the modulation effect in our experimental setting.


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•All-optical concept, i.e. reduced noises, reduced RF design considerations at high frequencies etc.•Short in comparison to existing optical devices.•Small wavelength sensitivity (no resonator).•Low finesse, i.e. no latency to reach steady state.•High extinction ratio.•Small power control signal.

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•Large in comparison to electronic transistors.•Operation rate is limited by the rate of plasma dispersion effect in silicon.•Not really cascadable since info and control are in different wavelengths (solution: TPA or band gap design).•The info signal is at high power.•Reduced energetic efficiency for info signal.

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Optical Viterbi decoderOptical Viterbi decoderZeev Zalevsky, Shai Ben Yaish, Eliyahu Guetta, Yevgeny Beiderman and Sharon Gannot

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2x2 2x2 2x2 2x2

Sampling by the detector

2x2 2x2 2x2 2x22x2 2x2 2x2 2x2

Sampling by the detector

VOA2x2 2x2 2x2

VOA

Optical 2x2 switchesLaser DetectorOptical attenuators

(VOA)

VOA2x2 2x2 2x2

VOA

VOA2x2 2x2 2x2

VOA

Optical 2x2 switchesLaser DetectorOptical attenuators

(VOA)

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Optical amplifier DetectorsA/D card for connecting to computer

Lasers

VOA

Optical switches Optical Y couplers and fibers

Optical amplifier DetectorsA/D card for connecting to computer

Lasers

VOA

Optical switches Optical Y couplers and fibers

‘0’ ‘1’

‘00’ ‘01’

‘11’

‘10’‘0’ ‘1’

‘00’ ‘01’

‘11’

‘10’

‘0’

‘1’

‘00’ ‘0’

‘1’‘01’

‘10’

‘11’

Current state Next state

Required commands

‘0’

‘1’

‘00’ ‘0’

‘1’‘01’

‘10’

‘11’

Current state Next state

Required commands

Viterbi realization- cont.

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Input

4 output detectors

Reference

Experimenting

Interferometer module. (a). Fringes in the output plane. (b). Shift of the fringes when relative phase is introduced between the input and the reference beams.

(a). The optical buffer loop (loop A or loop B). (b). The decision module. (c). The measurements of the VOA realizing the three possible attenuations.

(a). (b).

(c).

(a).

(b).

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Experimenting– cont.Realization of the optical buffer (loop A). Attenuation states that follow external commands coming according to the decisions made in every stage of the trellis diagram. In this example one may see 5 clear energy states.

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Experimenting– cont.

The experimental results measured at the outputs of the various 2 by 2 switches.

(a).

(b).

(c).

(d).

(e).

(a). The upper output of the first 2X2 switch (node M3). (b). The lower output of that switch (node M4). (c). The upper output of the second 2X2 switch (i.e. node M5). (d). The lower output of that switch (i.e. node M6). (e). The final output of the system at the detector (node M7).

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RF filtersRF filtersZeev Zalevsky, Amir Shemer, Shlomo Zach and David Mendlovic

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•The carrier frequency of the information is not known (1Ghz-20Ghz).•The signal BW is 100Mhz.•The SNR in the BW is 10dB.

Problem Definition

Over the entire spectrum the SNR is -13dB

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Finite Impulse Response Filters:an- coefficientsδt- delayss(t)- original signal

Theory∑−

=

δ−=1N

0nnT )tnt(sa)t(s

∑

∫

∫∑

∫

−

=

−

=

δμπ=μ

μπ−=μ

μμ=μπ−δ−=

=μπ−=μ

1N

0nn

1N

0nn

TT

)tni2exp(a)(F

dt)ti2exp()t(s)(S

)(F)(Sdt)ti2exp()tnt(sa

dt)ti2exp()t(s)(St2

1FIR δ

=ν

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Experimental Results

Schematic sketch of improved static system having high information efficiency throughput

Fiber Filter

1x2 Switches

Optical Feedback Fiber

Fiber Filter

1x2 Switches

Optical Feedback Fiber

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Additional experimental results for optical filter generated oveAdditional experimental results for optical filter generated over RF signal at r RF signal at the first replication:the first replication: a). The first replication without modulation. b). and c). The modulation frequency is below the spectral position of the filter. d). The modulation frequency is 34.682MHz. e). The modulation frequency is higher than the filter.

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Experiments at high frequencies:Experiments at high frequencies: a). The modulation frequency does not match the optical filter. b). Modulation frequency of 800MHz.

a). b).

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Detected replications with EDFA at the optical feedback loop:Detected replications with EDFA at the optical feedback loop:a). Replications without modulation. b). Replications with modulation at

414.2MHz.

a). b).

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The modulation frequency is:The modulation frequency is: a). below the optical notch. b). at the optical notch c). above it.

a). b). c).

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Nano-Second Fast Tunable & Reconfigurable RF-Photonic Spectrum Analyzer

Passive Optical System

time

F1F2

First burstSecond burst

tδt2δ

Passive Optical System

time

F1F2

First burstSecond burst

tδt2δ

System Configuration

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Experimental Design

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Three tapes, first replication

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Three tapes, second replication

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Passive & Temporally Continuous Optical Spectral Analyzer of RF Signals via Wavelength Coding•Spectral mapping without temporal lose of information•In Dispersion Chromatic Fibers (DCF) the time that light passes through is wavelength dependent•We realize two termed FIR notch filter by usage of DCF (i.e. different filter for different wavelengths)

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Experimental setup

Optical Modulator

Signal Generator

ASE Source

SCOPE High Speed Detectors

Electronic Modulator Driver

15517m compensating fiber delay path

DCF -808ps/nm

DWDM Demux

50%-50% Y coupler

Optical Modulator

Signal Generator

ASE Source




DCF -808ps/nm

DWDM DemuxOptical

Modulator

Signal Generator

ASE Source




DCF -808ps/nm

DWDM Demux

50%-50% Y coupler

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Two channel sampling for a wavelength filter using frequency of 485.27049 MHz and two DFB lasers

(b). Two channels with different wavelengths (1560.605nm & 1555.747nm) for modulation freq. of 331MHz (notch for 1560.605nm and pass band for 1555.747nm). (c). Two channels with different wavelengths (1560.605nm & 1555.747nm) for modulation frequency of 274MHz (notch for 1555.747nm & band pass for 1560.605nm).

(a). Two channels with different wavelengths (1560.605nm & 1555.747nm) for modulation freq. of 339MHz (pass band for both channels).

a). b).

c).

for λ= 1550.9nm (left) and for λ= 1557.4nm (middle) and the combined channels of the mid figure (blue) and the FFT of the signal (Red) using 50:50 Y-coupler (right).

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Experimental results- cont.

e). Two channels with different wavelengths (1560.605nm and 1558.172nm) for modulation frequency of 303MHz (pass band for 1560.605nm and notch for 1558.172nm). f). Two channels with different wavelengths (1560.605nm and 1558.172nm) for modulation frequency of 297MHz (pass band for both channels).

d).

e).

f).

d). Two channels with different wavelengths (1560.605nm and 1555.747nm) for modulation frequency of 393MHz (notch for both channels.

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Monitoring: In band OSNR Monitoring: In band OSNR network monitoring using network monitoring using periodic polarization modulationperiodic polarization modulationZeev Zalevsky, Dov Abraham, Vardit Eckhouse and Yevgeny Beiderman

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Experimental setup

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Experimental results seen at the digital scope. (a). Optical replication and appropriate polarization modulation of a sinusoidal sequence. (b). Optical replication and appropriate polarization modulation of a PRBS 231-1 input sequence. (c). Modulation of noise.

a). b). c).

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Experimental results after digital processing. a). Theoretical filter and the spectral band of the appearing information (signal + PMD + noise). b). The polarization modulation and replication of an input PRBS sequence with PMD and ASE noise. c). The polarization modulation of the ASE noise. d). The obtained experimental filter (the dashed lines indicate its contour). e). The correlation peak between sequence 1 and 3. f). The effective resulted experimental filter for the information (with PMD), the noise and the theoretical boundaries. g). The anticipated accuracy of the suggested technique for various DGD values and in comparison with the polarization nulling approach. h). The OSNR accuracy vs. DGD for various true OSNR values with apodization.

a). b). c). d).

e). f). g). h).

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Experimental results after digital processing. (a). The obtained experimental filter (the dashed lines indicate its contour). (b). The effective resulted experimental filter for the information (with PMD), the noise and the theoretical boundaries.

a). b).

factor of more than 40more than 40 between the attenuation of the signal with the PMD and the noise in the proper bandwidth

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ConclusionsWe have presented various approaches for:

•Processing & modulating•Analyzing & filtering•Monitoring & detecting

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PHOTONIC DEVICES AND MODULES FOR DATA PROCESSING