II nano-tera.ch
Prof. Ursula Keller (PI) Dr. Bauke Tilma Dr. Matthias Golling Mario Mangold Sandro Link Dominik Waldburger Cesare Alfieri
Vertical integration of ultrafast semiconductor lasers and their applications
Prof. Thomas Südmeyer Dr. Stephane Schilt Dr. Valentin Wittwer Nayara Jornod
Dr. Deran Maas Dr. Thomas Paul
start: Nov 2013
Dr. Jacques Morel Dr. Laurent Devenoges
Dr. Gábor Csúcs
Ultrafast lasers … generate coherent light pulses with pico- or femtosecond duration access ultrashort time scales
observe and use fast dynamics • understand chemical reaction dynamics • fast communication • …
pump-probe
optical clocking
2
a)
Ultrafast lasers … generate coherent light pulses with pico- or femtosecond duration access ultrashort time scales
observe and use fast dynamics • understand chemical reaction dynamics • fast communication • …
concentrate in time and space
achieve extremely high intensities • material processing • multi-photon biomedical imaging 30 µm a)• b) …
Brain Research Institute Prof. Fritjof Helmchen Fabian Voigt 30 µm
b)
pollen grains
50 µm
c)
brain tissue of mouse
50 µm
3
Ultrafast lasers … generate coherent light pulses with pico- or femtosecond duration access ultrashort time scales
concentrate in time and space
observe and use fast dynamics • understand chemical reaction dynamics • fast communication • … achieve extremely high intensities • material processing • multi-photon biomedical imaging • …
intensity
broad optical spectrum
frequency
generate ultrastable frequency combs • high precision spectroscopy • optical clocks • … 4
MIXSEL II
Frequency combs
Multiphoton microscopy
Spectroscopy
Metrology applications
Product development
MIXSEL prototype 5
Ultrafast semiconductor lasers: our approach and goals gain • completely fabricated at ETH Zürich • very compact lasers few µm few
loss µm
• waver-scale production • cost efficient
6
Ultrafast semiconductor lasers: our approach and goals gain
VECSEL Vertical External Cavity Surface Emitting Laser
7
Ultrafast semiconductor lasers: our approach and goals gain loss SESAM
VECSEL Vertical External Cavity Surface Emitting Laser
+
Semiconductor Saturable Absorber Mirror
8
Ultrafast semiconductor lasers: our approach and goals VECSEL gain chip
Emitting Laser
+
n ct io se
AR
re gi on n ga i
M i bo rr tto o m r D
at s he
SESAM
VECSEL Vertical External Cavity Surface
in k
loss
BR
gain
Semiconductor Saturable Absorber Mirror
9
Ultrafast semiconductor lasers: our approach and goals VECSEL gain chip
n ct io se
AR
n ga i
BR
M i bo rr tto o m r D
at s
Semiconductor Saturable Absorber Mirror
ab so AR rbe r se ct io n
BR
D
ir bo ro tto r m
M
bs
tra te
SESAM
su
Emitting Laser
+
he
SESAM
VECSEL Vertical External Cavity Surface
in k
loss
re gi on
gain
10
Ultrafast semiconductor lasers: our approach and goals gain loss SESAM
VECSEL Vertical External Cavity Surface Emitting Laser
+
Semiconductor Saturable Absorber Mirror
MIXSEL
=
Modelocked Integrated External-Cavity Surface Emitting Laser
11
Ultrafast semiconductor lasers: our approach and goals gain loss SESAM
=
Semiconductor Saturable Absorber Mirror
Modelocked Integrated External-Cavity Surface Emitting Laser
ab s pu orb m er p D BR ga in re gi on AR se ct io n
la
M
irr o se r rD
BR
MIXSEL chip
in k
Emitting Laser
+
at s
Vertical External Cavity Surface
MIXSEL
he
VECSEL
12
Targeted laser performance Average output power
10 W
Goal:
1 W
• ultra short pulses ≤ 100 fs 100 mW
• several hundreds mW average output power
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
13
Targeted laser performance Average output power
10 W
Goal:
1 W
• ultra short pulses ≤ 100 fs 100 mW
• several hundreds mW average output power
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
For example for supercontinuum generation for stabilized optical frequency combs
applications for optical frequency combs ● ● ● ●
coherent communication spectroscopy optical clocks comb metrology
14
Frequency combs from modelocked lasers I(ω)
train of evenly spaced pulses
equidistant frequency comb
frep
E(t) t
1 / frep
FT
ω
15
Frequency combs from modelocked lasers I(ω)
train of evenly spaced pulses
equidistant frequency comb
frep
E(t) t
FT
ω
1 / frep
Optical Frequency Combs
intensity
frep fCEO
fn = m frep + fCEO CEO: carrier envelope offset
frequency Telle, et al., Appl. Phys. B 69, 327 (1999) Diddams, et al., Phys. Rev. Lett. 84, 5102 (2000) 16
Frequency combs from modelocked lasers I(ω)
train of evenly spaced pulses
equidistant frequency comb
frep
E(t) t
FT
ω
1 / frep
Optical Frequency Combs undefined, optical intensity intensity frequency
phase-stable link: optical to microwave
beat
THz
MHz frequency frequency
Telle, et al., Appl. Phys. B 69, 327 (1999) Diddams, et al., Phys. Rev. Lett. 84, 5102 (2000) 17
Targeted laser performance Average output power
10 W
Goal:
1 W
• ultra short pulses ≤ 100 fs 100 mW
• several hundreds mW average output power
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
optical frequency combs
required: ●
octave-spanning & coherent
●
very broad optical spectrum: supercontinuum detection of fCEO
υ
18
Supercontinuum generation and CEO detection Average output power
10 W
1 W
100 mW
10 mW VECSEL
MIXSEL
pulse duration: 231 fs average output power: 100 mW repetition rate: 1.75 GHz center wavelength: 1038 nm
1 mW 100 fs
1 ps Pulse duration
C. A. Zaugg, A. Klenner, M. Mangold, A. S. Mayer, S. M. Link, F. Emaury, M. Golling, E. Gini, C. J. Saraceno, B. W. Tilma, U. Keller, Optics Express, vol. 22, No. 13, pp. 16445-16455, 2014 19
Supercontinuum generation and CEO detection Average output power
10 W
1 W
amplification in Yb-doped fiber amplifier 100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
C. A. Zaugg, A. Klenner, M. Mangold, A. S. Mayer, S. M. Link, F. Emaury, M. Golling, E. Gini, C. J. Saraceno, B. W. Tilma, U. Keller, Optics Express, vol. 22, No. 13, pp. 16445-16455, 2014 20
Supercontinuum generation and CEO detection Average output power
10 W
1 W
pulse compression in LMA fiber 100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
C. A. Zaugg, A. Klenner, M. Mangold, A. S. Mayer, S. M. Link, F. Emaury, M. Golling, E. Gini, C. J. Saraceno, B. W. Tilma, U. Keller, Optics Express, vol. 22, No. 13, pp. 16445-16455, 2014 21
Supercontinuum generation and CEO detection Average output power
10 W
[1] H. R. Telle, G. Steinmeyer, A. E. Dunlop, J. Stenger, D. H. Sutter and U. Keller, Applied Physics B 69, 327 (1999)
1 W
coherent supercontinuum generation in nonlinear fiber
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
supercontinuum
[1]
C. A. Zaugg, A. Klenner, M. Mangold, A. S. Mayer, S. M. Link, F. Emaury, M. Golling, E. Gini, C. J. Saraceno, B. W. Tilma, U. Keller, Optics Express, vol. 22, No. 13, pp. 16445-16455, 2014 22
Supercontinuum generation and CEO detection Average output power
10 W
[1] H. R. Telle, G. Steinmeyer, A. E. Dunlop, J. Stenger, D. H. Sutter and U. Keller, Applied Physics B 69, 327 (1999)
1 W
coherent supercontinuum generation in nonlinear fiber
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps
RBW 100 kHz fCEO 1
-25 -50
frep=1.75 GHz fCEO 2
fCEO detection
frep
intensity
int. (dBc)
Pulse duration
fCEO
-75
-100
frequency 0.0
0.5 1.0 1.5 frequency (GHz)
[1]
C. A. Zaugg, A. Klenner, M. Mangold, A. S. Mayer, S. M. Link, F. Emaury, M. Golling, E. Gini, C. J. Saraceno, B. W. Tilma, U. Keller, Optics Express, vol. 22, No. 13, pp. 16445-16455, 2014 23
Supercontinuum generation and CEO detection Average output power
10 W
1 W
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
goal: improve performance of the lasers further to get rid of amplification and compression stage
C. A. Zaugg, A. Klenner, M. Mangold, A. S. Mayer, S. M. Link, F. Emaury, M. Golling, E. Gini, C. J. Saraceno, B. W. Tilma, U. Keller, Optics Express, vol. 22, No. 13, pp. 16445-16455, 2014 24
147-fs high-power ultrafast VECSEL Average output power
10 W
1 W
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
25
147-fs high-power ultrafast VECSEL Average output power
10 W
1 W
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
shortest pulse duration from a highpower ultrafast SDL
pulse duration: 147 fs average output power: 100 mW repetition rate: 1.82 GHz peak power: 328 W
D. Waldburger, M. Mangold, S. M. Link, M. Golling, E. Gini, B. W. Tilma, U. Keller, accepted at CLEO US 2015 26
Shortest pulses of a MIXSEL Average output power
10 W
1 W
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
M. Mangold, D. Waldburger, S. M. Link, M. Golling, E. Gini, B. W. Tilma, U. Keller, accepted at CLEO/Europe 2015 27
Shortest pulses of a MIXSEL Average output power
10 W
1 W
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
pulse duration: 253 fs average output power: 235 mW repetition rate: 3.35 GHz center wavelength: 1044 nm
cavity length: 44.7 mm
shortest pulse duration from a MIXSEL
M. Mangold, D. Waldburger, S. M. Link, M. Golling, E. Gini, B. W. Tilma, U. Keller, accepted at CLEO/Europe 2015 28
Fiber dispersion modelling supercontinuum generation 1 W
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
SEM image of fiber
spectrum
Average output power
10 W
simulated dispersion wavelength [nm]
29
Prototypes for noise characterization 2 VECSEL prototypes
19 cm
25 cm
noise characterization frequency stabilization
30
2 Photon-microscopy 30 µm
Brain tissue b)of a mouse
a)
50 µm
c)
Pollen grains Brain Research Institute Prof. Fritjof Helmchen Fabian Voigt
a)
30 µm
b)
50 µm
31
Application: Dual-comb spectroscopy possible gas spectroscopy setup
Acetylene has strong absorption lines in the near infrared around 1035 nm.
absorption [%]
requirement: 2 modelocked lasers with slightly different pulse repetition frequencies
wavelength [nm] 32
Dual-comb MIXSEL
33
Dual-comb MIXSEL
34
Dual-comb MIXSEL
Two pulsed lasers from one MIXSEL chip
35
Dual-comb MIXSEL ∆λ = 0.25 nm
0.6 0.4 0.2 0.0
0.8 0.6
966.0 967.0 wavelength [nm] meas
τp = 13.5 ps
sech
2
fit
0.4 0.2 0.0 -40 0 40 delay [ps]
output power [mW] pulse repetition
spectral intensity [arb. u.]
1.0
0.8
λc = 966.11 nm
p-polarized beam 1.0
autocorrelation [arb. u.]
spectral intensity [arb. u.]
1.0
autocorrelation [arb. u.]
s-polarized beam
1.0
λc = 966.01 nm
0.8 ∆λ =
0.6 0.23 nm 0.4 0.2 0.0
966.0 967.0 wavelength [nm] meas
0.8
sech fit
0.6
2
τp = 19.1 ps
0.4 0.2 0.0
-40 0 40 delay [ps]
s-pol
p-pol
76
70
1.895
1.890
frequency [GHz]
36
Dual-comb MIXSEL
amplitude [dBc]
comb1
span 150 MHz RBW 1 kHz
-10
0.4 0.2 0.0
0.8 0.6
966.0 967.0 wavelength [nm] meas
τp = 13.5 ps
sech
2
fit
0.4 0.2 0.0 -40 0 40 delay [ps]
0.48
0.52 frequency [GHz]
0.56
pulse repetition
spectral intensity [arb. u.]
∆λ = 0.25 nm
0.6
output power [mW]
-20 0.44
1.0
0.8
λc = 966.11 nm
p-polarized beam 1.0
autocorrelation [arb. u.]
0
spectral intensity [arb. u.]
microwave comb
1.0
autocorrelation [arb. u.]
s-polarized beam
1.0
λc = 966.01 nm
0.8 ∆λ =
0.6 0.23 nm 0.4 0.2 0.0
966.0 967.0 wavelength [nm] meas
0.8
sech fit
0.6
2
τp = 19.1 ps
0.4 0.2 0.0
-40 0 40 delay [ps]
s-pol
p-pol
76
70
1.895
1.890
frequency [GHz]
direct link between the terahertz frequencies and the electronically accessible microwave regime S. M. Link, A. Klenner, M. Mangold, C. A. Zaugg, M. Golling, B. W. Tilma, U. Keller, Optics Express, vol. 23, No. 5, pp. 5521-5531, 2015 37
Dual-comb MIXSEL
amplitude [dBc]
comb1
span 150 MHz RBW 1 kHz
-10
∆λ = 0.25 nm
0.6 0.4 0.2 0.0
0.8 0.6
966.0 967.0 wavelength [nm] meas
τp = 13.5 ps
sech
2
fit
0.4 0.2 0.0 -40 0 40 delay [ps]
output power [mW]
-20 0.44
0.48
0.52 frequency [GHz]
0.56
pulse repetition
spectral intensity [arb. u.]
1.0
0.8
λc = 966.11 nm
p-polarized beam 1.0
autocorrelation [arb. u.]
0
spectral intensity [arb. u.]
microwave comb
1.0
autocorrelation [arb. u.]
s-polarized beam
1.0
λc = 966.01 nm
0.8 ∆λ =
0.6 0.23 nm 0.4 0.2 0.0
966.0 967.0 wavelength [nm] meas
0.8
sech fit
0.6
2
τp = 19.1 ps
0.4 0.2 0.0
-40 0 40 delay [ps]
s-pol
p-pol
76
70
1.895
1.890
frequency [GHz]
Swiss patent application 01498/14, filed 2 October 2014 S. M. Link, A. Klenner, M. Mangold, C. A. Zaugg, M. Golling, B. W. Tilma, U. Keller, Optics Express, vol. 23, No. 5, pp. 5521-5531, 2015 38
MIXSEL II
Frequency combs
Multiphoton microscopy
Spectroscopy
Metrology applications
Product development
MIXSEL prototype 39
MIXSEL II
Frequency combs
Multiphoton microscopy
Average output power
10 W
1 W
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
Spectroscopy
Metrology applications
Product development
MIXSEL prototype 40
MIXSEL II
Frequency combs
Multiphoton microscopy
Average output power
10 W
1 W
100 mW
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
Spectroscopy
Metrology applications
Product development
MIXSEL prototype 41
MIXSEL II
30 µm
a)
Frequency combs
50 µm
b)
Multiphoton microscopy
Average output power
10 W
1 W
100 mW
50 µm
c)
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
Spectroscopy
Metrology applications
Product development
MIXSEL prototype 42
MIXSEL II
30 µm
a)
Frequency combs
50 µm
b)
Multiphoton microscopy
Average output power
10 W
1 W
100 mW
50 µm
c)
10 mW VECSEL
MIXSEL
1 mW 100 fs
1 ps Pulse duration
Spectroscopy
Metrology applications
Product development
MIXSEL prototype 43
MIXSEL II
Frequency combs
Multiphoton microscopy
Spectroscopy
Metrology applications
Product development
MIXSEL prototype 44
45
Overview – ultrafast progress
Average output power
10 W
1 W
100 mW
'VECSEls Keller' 'MIXSELs' 'VECSELs others'
10 mW
1 mW 100 fs Alexander Klenner
1 ps Pulse duration
10 ps
Nov. 2013 May 2015
Overview – ultrafast progress 10 kW
Peak power
1 kW
'Peak Power VECSELs Keller' 'Peak Power MIXSELs ' 'Peak Power VECSELs others'
100 W 10 W 1 W 100 mW 100 fs
Alexander Klenner
1 ps 10 ps Pulse duration
Nov. 2013 May 2015
1200
mm 0 75 % 0 .5
1000
4
m 0m 0 10 % 0 .5
m 0m 0 15 % 0.5
3
800 600 400 200 04
m 00 2 = C 1% O R = T OC 5
6
2
m
7
Pulse duration (ps)
Output power (mW)
Repetition-rate scaling of MIXSEL 1400
mm 0 50 % 0.7
8
9
10
1 2
3
4
5
6
7
8
Repetition rate (GHz)
• Repetition rate-tuning from 5 GHz to 101 GHz with single MIXSEL structure [1] • Watt-level operation up to 15 GHz • Femtosecond operation at 60 GHz and 101 GHz • M2 < 1.1 for all measurements
0 100
9
MIXSEL-chip pump
cavity length reduction: 29.4 mm to 1.49 mm (frep from 5.1 GHz to 101.2 GHz)
output coupler
o ut p ut
M. Mangold, C. A. Zaugg, S. M. Link, M. Golling, B. W. Tilma, U. Keller, Opt. Express 22, pp. 6099-6107 (2014) 48
Comb spectroscopy for process control at ABB application: acetylene (C2H2) in ethylene (C2H4)
Ethylene is the most widely produced petrochemical with >100 million tons per year and a 20 billion USD market size
Acetylene is a byproduct of the ethylene production and considered an impurity in the final product
Traditionally gas chromatography are used to monitor acetylene slow response and high maintenance < 100 ppm acetylene
< 1 ppm acetylene
cracked gas > 1000 ppm acetylene
catalytic reactor
catalytic reactor
add CO2, H2
< 10 ppm acetylene
Comb spectroscopy for process control at ABB proposed solution
Frequency comb spectroscopy is a powerful new technology with numerous strengths: fast measurement speed high resolution broad spectrum simultaneous measurement of multiple species in-situ measurements
3 HITRAN:C2H2 2.5
2 absorption (%)
Acetylene has strong absorption lines in the near infrared around 1035 nm.
1.5
1
0.5
0 1010
1015
1020
1025
1030 wavelength (nm)
1035
1040
1045
1050
Comb spectroscopy for process control at ABB experimental setup MIXSEL 1
gas cell
frep = 1 GHz
digitizer
signal processing
MIXSEL 2 frep = 1 GHz + Δf 3
HITRAN:C2H2 2.5
2 absorption (%)
Simulated spectrum Repetition rate is 1 GHz (dot spacing) The resolution is sufficient to reconstruct the absorption spectrum and accurately compute the acetylene concentration
1.5
1
0.5
0 289.65
289.7
289.75
289.8
289.85 frequency (THz)
289.9
289.95
290
290.05
52
53
Milestones MIXSEL II (proposal) X
max. av. power 600 mW
X
+ pulse rep. rate scaling 5-100 GHz
X
year 3 milestone done
x
vention and surprise:
cked MIXSEL with picosecond pulses
Start 1. Nov. 2013
April 2015 1.5 years/18 mos
M. Mangold, C. A. Zaugg, M. Golling, B. W. Tilma, U. Keller,Optics Express, vol. 23, No. 5, pp. 5521-553
Oct. 2014 54
Milestones 1.1
April 2015 1.5 years/18 mos
1.1 Ultrafast OP-VECSEL with sub-300-fs pulse durations and >1 W average power: 1.1.1: First sub-300-fs pulses with >1W average power (year 1) Best result so far: 269 fs, 605 mW, 1.84 GHz, 1.07 kW peak power Shortest pulses so far: 147 fs, 100 mW, 1.82 GHz, 328 W peak power D. Waldburger, M. Mangold, S. M. Link, M. Golling, E. Gini, B. W. Tilma, U. Keller, CLEO US 2015, Talk SM3F.2
1.1.2 and 1.1.3: SESAM optimization and 1:1 modelocking: novel fast QW saturable saturable absorbers, based on LT InGaAs in AlAs barrier more details in 1.2.2 55
Milestones 1.2
April 2015 1.5 years/18 mos
1.2 OP-MIXSELs with femtosecond pulse durations and more than 1 W average power: 1.2.1: First working device at any power: ok, 620 fs, 101 mW, 4.8 GHz, 967.7 nm M. Mangold, V. J. Wittwer, C. A. Zaugg, S. M. Link, M. Golling, B. W. Tilma, U. Keller, Opt. Express 21, 24904-24911 (2013)
In addition: Pulse repetition rate scaling to 100 GHz M. Mangold, C. A. Zaugg, S. M. Link, M. Golling, B. W. Tilma, U. Keller, Opt. Express 22, pp. 6099-6107 (2014)
1.2.2: Integrated saturable absorber optimization and characterization: at this point all based on fast quantum well (QW) absorbers Future: move towards QD absorbers and more power (>1 W milestone year 3) 56
Milestones 1.3
April 2015 1.5 years/18 mos
1.3 OP-MIXSELs with <300 fs and >1 W average power: 1.3.1: First working device at any power: year 3 milestone ok, 253 fs, 235 mW, 3.35 GHz, 1044 nm M. Mangold, D. Waldburger, S. M. Link, M. Golling, E. Gini, B. W. Tilma, U. Keller, CLEO/Europe 2015, upgraded to Invited Talk CF-4.1
Using QW saturable absorber in AlAs barrier integrated (MBE/MOCVD growth) 57
Milestones 2.2
April 2015 1.5 years/18 mos
2.2 Coherent supercontinuum generation for stable frequency comb generation:
2.2.1: Develop a broadband white light dispersion measurement system for fibers (year 1) Design done, parts ordered and arriving – work in progress by UniNeu, Südmeyer 2.2.2: Numerical simulation and optimization of SCG (moved to ≈1030 nm) 2.2.3: First coherent octave-spanning SCG from a semiconductor laser (Keller): explained in Milestone 3.2.1 58
Milestones 3.1
April 2015 1.5 years/18 mos
3.1 Noise evaluation and optimization of ultrafast VECSELs/MIXSELs (Südmeyer, Morel): Prototypes delivered to UniNEU and METAS Mar/Apr 2015 (Südmeyer, Morel) Poster presentation with latest noise characterization Picosecond MIXSEL noise characterization M. Mangold, S. M. Link, A. Klenner, C. A. Zaugg, M. Golling, B. W. Tilma, U. Keller, IEEE Photonics Journal 6, 1500309 (2014) MIXSEL: >645 mW output power, 14.3 ps pulses, 2 GHz pulse reprate • 127 fs timing jitter – free-running [100 Hz, 100 MHz] • 31 fs timing jitter – stabilized [100 Hz, 100 MHz] • < 0.15% amplitude noise [1 Hz, 10 MHz] 59
Milestones 4
April 2015 1.5 years/18 mos
4 Prototype lasers for application demonstrations, UniZH, UniNeu, Metas (Keller): First generation strain-compensated SESAM modelocked VECSELs UniZH Prof. Helmchen, biomedical imaging, summer 2014: 263 fs, 1.77 GHz, 360 mW Gigahertz pulse repetition rate needs samples with scattering but less absorption UniNeu and METAS, prototype delivered Feb/March 2015: UniNeu: 255 fs, 1.77 GHz, 120 mW METAS: 203 fs, 1.77 GHz, 80 mW 60
Milestones 5
April 2015 1.5 years/18 mos
Dual-comb MIXSEL
5 Application demonstrations: 5.1 UniZH Prof. Helmchen, biomedical imaging, summer 2014: 263 fs, 1.77 GHz, 360 mW Gigahertz pulse repetition rate needs samples with scattering but less absorption METAS and ABB are getting prepared for prototype delivery 61