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Final Year Projects in Integrated Photonics
Integrated Photonics Group
Slide 1 September 19, 2018 Final Year Projects in Integrated Photonics
The Internet – not slowing yet
Slide 2 September 19, 2018 Final Year Projects in Integrated Photonics
How is the internet transmitted?
Final Year Projects in Integrated Photonics September 19, 2018 Slide 3
Optical vs. Copper vs. Wireless
Final Year Projects in Integrated Photonics September 19, 2018 Slide 4
Wireless Copper
100s of km
>99% of the internet is over optical fibre
How is light used?
Final Year Projects in Integrated Photonics September 19, 2018 Slide 5
Light is turned on and off, for digital ones and zeros
Then, multiple colours can also be used…
Final Year Projects in Integrated Photonics September 19, 2018 Slide 6
Can we just keep adding more wavelengths at higher data rates?
Increase the number of colours?
Available space in optical fibre
The channels eventually interfere! Slide 7 September 19, 2018 Final Year Projects in Integrated Photonics
Increase the data rate?
Available space in optical fibre
The channels eventually interfere!
2!
≥ΔΔ tE νhE = ↑Δ↓Δ νt
Slide 8 September 19, 2018 Final Year Projects in Integrated Photonics
The end is near…
1983 1988 1993 1998 2003 2008 2013
WDMTDMOFDM/CoWDMCoherent Detection
Bit
Rat
e D
ista
nce
Pro
duct
(Tbi
t/s.
km)
106
105
104
103
102
10
1
.1
1983 1988 1993 1998 2003 2008 2013
WDMTDMOFDM/CoWDMCoherent Detection
Bit
Rat
e D
ista
nce
Pro
duct
(Tbi
t/s.
km)
106
105
104
103
102
10
1
.1
1983 1988 1993 1998 2003 2008 2013
WDMTDMOFDM/CoWDMCoherent Detection
Bit
Rat
e D
ista
nce
Pro
duct
(Tbi
t/s.
km)
106
105
104
103
102
10
1
.1Laboratory Results
Fundamental Limit (for ones and zeros)
New technology implemented
Final Year Projects in Integrated Photonics September 19, 2018 Slide 9
What improvements are possible?
Final Year Projects in Integrated Photonics September 19, 2018 Slide 10
Use 2 orthogonal polarisations: • Increases bandwidth by 2x • Done (boring)
Polarisation
What improvements are possible?
Final Year Projects in Integrated Photonics September 19, 2018 Slide 11
Use N orthogonal modes of optical fibre: • Increases bandwidth by N • Very current, very expensive
Space
Light path
What improvements are possible?
The Amplitude
The Phase No Signal
Final Year Projects in Integrated Photonics September 19, 2018 12
Amplitude & Phase
What improvements are possible?
2bits/pulse 4 bits/pulse 5 bits/pulse
Amplitude & Phase
Already implemented and expensive: • But room to invent more cost effective
solutions using interesting Physics Final Year Projects in Integrated Photonics September 19, 2018 Slide 13
An example…
Final Year Projects in Integrated Photonics September 19, 2018 Slide 14
Superchannels Separate Channels
What improvements are possible?
Available Frequency
Coherence
Final Year Projects in Integrated Photonics September 19, 2018 Slide 15
What improvements are possible?
Available Frequency
Superchannels
Requires coherent op=cal comb
Coherence
No current commercial solutions: • Focus of research group
Final Year Projects in Integrated Photonics September 19, 2018 Slide 16
Just like your phone except faster
Final Year Projects in Integrated Photonics September 19, 2018 Slide 17
Optics: 4 carrier × 25G symbols/sec × 4 bits/symbol × 2 pol. =800 Gbps
Modulator
Modulator
Modulator
Laser Comb
What we want on a single chip
Final Year Projects in Integrated Photonics September 19, 2018 Slide 18
Modulator
Modulator
Modulator
Required components
Laser Comb
Low linewidth laser
Comb genera=on
Op=cal Mux Op=cal Demux
Integrated Modulators
!
! !
! "
None suitable commercially for narrowly spaced coherent combs
Final Year Projects in Integrated Photonics September 19, 2018 Slide 19
Design of Integrated Optical Demultiplexers
SEM image of a 1x4 MMI integrated with slo9ed Fabry-‐Pérot slave lasers
The current design of the integrated op=cal demul=plexers works by: 1. Passively splits the injected comb using a Mul=mode Interferometer (MMI) 2. Injec=on locks a slave laser to each line in the op=cal comb.
Side Mode Suppression RaDo
SMSR
Passive power spli9er InjecDon locked
slave laser
Final Year Projects in Integrated Photonics September 19, 2018 Slide 20
TLS: Tuneable laser source PC: PolarizaDon controller MZM: Mach-‐Zehnder modulator EDFA: Erbium doped fibre amplifier PIC: Photonic integrated circuit OSA: OpDcal spectrum analyser
OpDcal Comb Generated
Wavelength(nm)
Power (d
Bm)
Laser injection locking
Wavelength(nm)
Power (d
Bm)
Laser injection locking
Injected Comb
Slave laser’s lasing mode
Slave laser’s side mode
Wavelength(nm)
Power (d
Bm)
SMSR
Laser injection locking
Types of Projects
# Simulation: $ Solving analytical equations $ Based on existing code $ Requiring code development
# Experimental # Mix of Experiment and Theory
Slide 24 September 19, 2018 Final Year Projects in Integrated Photonics
Laser TestingDevelop LabView based characterisation of diode lasers including: # Electrical # Optical # Gain Possible theoretical simulation and analysis addition available.
Final Year Projects in Integrated Photonics September 19, 2018 Slide 25
Project #1 – Laser Measurements
Dual comb generation chip
Final Year Projects in Integrated Photonics September 19, 2018 Slide 26
A ring laser
September 19, 2018 Slide 27
Ring
CW
CCW
Ring
CW
CCW
Project #2 – Laser Theory
Final Year Projects in Integrated Photonics
Laser linewidth
Final Year Projects in Integrated Photonics September 19, 2018 Slide 28
Δ𝐸Δ𝑡≥ ℏ/2 Δ𝜈Δ𝑡≥ 1/4𝜋
How long does an electromagnetic wave retain mathematical perfection?
𝐸= 𝐸↓0 𝑒↑𝑖(𝑘𝑥−𝜔𝑡) Δ𝑡↓𝑐 : Coherence time Δ𝑙↓𝑐 =cΔ𝑡↓𝑐 : Coherence length Δ𝜈↓𝑐 : Linewidth
Student will learn to characterize noise of and measure laser linewidth: # Using loss-compensated recirculating delayed self-heterodyne
interferometer (LC-RDSHI) # Sources of Noise in
$ Electrical Test Equipment $ Optical Test Equipment
Laser Linewidth Characterisation
Final Year Projects in Integrated Photonics September 19, 2018 Slide 29
-80
-70
-60
-50
-40
-30
-20
-10 0.00E+00 5.00E+08 1.00E+09
Pow
er L
evel
/ dB
m
Frequency / Hz
Project #3 –Laser Linewidth Characterisation
Starting Mode in Waveguide
Slide 30 September 19, 2018 Final Year Projects in Integrated Photonics
Starting Mode enters larger region
Slide 31 September 19, 2018 Final Year Projects in Integrated Photonics
Light Propagates through device
Slide 32 September 19, 2018 Final Year Projects in Integrated Photonics
Starting Mode exits in two pieces
Slide 33 September 19, 2018 Final Year Projects in Integrated Photonics
Top View
Slide 34 September 19, 2018 Final Year Projects in Integrated Photonics
Project #4 – Optical Simulations (more than one topic possible)
PICdraw – Custom Design tool
Final Year Projects in Integrated Photonics September 19, 2018 Slide 35
Mathematical based design # Custom software used
to design the complex devices
Slide 36 September 19, 2018 Final Year Projects in Integrated Photonics
Simulation and fabrication of complex photonic devices
Project #5 – Software for Photonic Device Design
Slide 37 September 19, 2018 Final Year Projects in Integrated Photonics
Get your hands dirty?
Project #6 – Making Stuff (come and talk to me…)
Slide 38 September 19, 2018 Final Year Projects in Integrated Photonics
e.g. Czerny-Turner spectrometer
Final Year Projects in Integrated Photonics September 19, 2018 Slide 39
6 possible project areas:
September 19, 2018 Slide 40
Please contact me if you have any questions about any of the project options.
Final Year Projects in Integrated Photonics
Experiment Theory Programming1 Laser Measurements Yes possible LabView2 Laser Theory No Yes likely3 Laser Linewidth Yes Yes LabView4 Simulations No Yes likely5 Optical design tools No Yes C++6 Making things Yes ? ?
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