1. Present myself and the group Present our current research on: “title”
Kerr lens mode-locked femtosecond thin-disk lasers: towards powerful sub-50 fs oscillators
Norbert Modsching, Clément Paradis, François Labaye, Maxim Gaponenko,
Valentin J. Wittwer, Thomas Südmeyer
Laboratoire Temps-Fréquence, Université de Neuchâtel,
Neuchâtel, Switzerland
Present myself and the group
Present our current research on: “title” 

2. Motivation for high-power laser sources
Applications
Need
High field science
Wavelength conversion
Frequency comb generation
Sub-100-fs pulses
High repetition rate
High average power (beneficial)

3. Power-scalable ultrafast laser architectures
Fiber amplifier
Innoslab amplifier
P. Russbueldt et al., Opt. Lett. 35, 4169–4171 (2010).
T. Eidam et al., Opt. Lett. 35, 94–96 (2010).
Thin-disk oscillator / amplifier
ddisk ≈100 μm
A. Giesen et al., Appl. Phys. B 58, 365–372 (1994).
JP Negel et al., Opt. Express 23, 21064–21077 (2015).

4. Motivation for high-power laser oscillators
Applications
Need
High field science
Wavelength conversion
Frequency comb generation
Sub-100-fs pulses
High repetition rate
High average power (beneficial)
Thin-disk laser (TDL) oscillators
External spectral broadening and pulse compression required
Photoelectron
imaging spectroscopy
High harmonic
generation
Mid-infrared
generation
T. Südmeyer et al., Nat. Photonics 2, 599–604 (2008)
F. Emaury et al., Optica 2, 980–984 (2015)
I. Pupeza et al., Nat. Photonics 9, 721–724 (2015)

5. Motivation for high-power laser oscillators
Applications
Need
High field science
Wavelength conversion
Frequency comb generation
Sub-100-fs pulses
High repetition rate
High average power (beneficial)
Thin-disk laser (TDL) oscillators
First TDL oscillator delivering: >10 W, sub-100-fs
1.6 W, 35 fs
References:
C. Paradis et al., Opt. Express 25, (2017)

6. Key ingredients for short pulses from Yb-based oscillators
Key ingredients for short pulses from Yb-based oscillators
Pulse duration timeline
Mode locking schemes for TDLs
[1] J. A. der Au et al., Opt. Lett. 25, 859–861 (2000).
SESAM
Taken from: A. Diebold et al., Opt. Express 24, (2016).
Yb:YAG
ETH
Kerr lens mode locking
[3] O. Pronin et al., Opt. Lett. 36, 4746–4748 (2011).
[1]
[3]
Yb:YAG
MPQ
Yb:LuScO ETH
[4]
[4] J. Zhang et al., in CLEO (2015), PDA1.
[2] C. Schriber et al., in ASSL (2014), AF1A.4.
[2]
Yb:CALGO ETH
5 mm
Gain materials
Dlem FWHM (nm)
k (Wm-1K-1) (ndot ~7×1020 cm-3)
Melting temp. (°C)
Yb:YAG
9 ( ↔ 124 fs)
7.5
1940
Dlem FWHM (nm)
k (Wm-1K-1) (ndot ~7×1020 cm-3)
Melting temp. (°C)
Yb:YAG
9 ( ↔ 124 fs)
7.5
1940
Yb:Lu2O3
13 ( ↔ 87 fs)
12.3
2400
Ytterbium doped Lutetium oxyde: Yb:Lu2O3: Yb:LuO

7. Mode locking results: Yb:Lu2O3 thin-disk laser
Mode locking results: Yb:Lu2O3 thin-disk laser
Pulse duration timeline
CM1 OC KM HA
CM3
0.8 m
0.4 m
Pump
Thin disk
CM2
Laser cavity
Yb:Lu2O3
61 MHz repetition rate
3.5 W
2 W
[4]
[4] J. Zhang et al., in CLEO (2015), PDA1.
[2] C. Schriber et al., in ASSL (2014), AF1A.4.
[2]
37 fs, 1.5 W [5]
[5] Sévillano et al., in CLEO (2014), STu2E.1.
Gain materials
Mode-locked performance
Dlem FWHM (nm)
k (Wm-1K-1) (ndot ~7×1020 cm-3)
Melting temp. (°C)
Yb:YAG
9 ( ↔ 124 fs)
7.5
1940
Yb:Lu2O3
13 ( ↔ 87 fs)
12.3
2400
Pulse duration
49 fs
Output power
4.5 W
Spectral bandwidth FWHM
24 nm
GDD per RT
-1100 fs²
Output coupling rate
2.7 %
TBP (ideal sech2: 0.315)
0.322
Opt-to-opt efficiency
4.7 %
Pulse duration
49 fs
35 fs
Output power
4.5 W
1.6 W
Spectral bandwidth FWHM
24 nm
34 nm
GDD per RT
-1100 fs²
-1000 fs²
Output coupling rate
2.7 %
0.9 %
TBP (ideal sech2: 0.315)
0.322
0.330
Opt-to-opt efficiency
4.7 %
2.1 %
40 fs 1.1 W
35 fs 280 mW
32 fs 10 mW
*inversion level: 0.1
C. Paradis et al., Opt. Express 25, 14918–14925 (2017).

8. Mode locking results: Power scaling
Mode locking results: Power scaling
Power scaling of KLM TDL
Laser cavity
Yb:Lu2O3
CM1 OC KM HA
CM3
0.8 m
0.4 m
Pump
Thin disk
CM2
CM1 OC KM HA
CM3
0.8 m
0.4 m
Pump
Thin disk
CM2
[1] J. Brons et al., Opt. Lett. 41, 3567 (2016).
40 fs 1.1 W
35 fs 280 mW
32 fs 10 mW

9. Towards shorter pulse durations
Towards shorter pulse durations
Pulse duration timeline
Laser cavity
Yb:CALGO
Proof-of-principle demonstration
Low quality disk
124 MHz repetition rate
Yb:YAG
Yb:LuScO
Yb:CALGO
CM2 OC KM HA
0.9 m
0.3 m
CM1
Pump
Thin disk
Yb:Lu2O3
26 mW [6]
[6] J. Ma et al., Opt. Lett. 41, 890 (2016).
Mode-locked performance
Gain materials
Dlem FWHM (nm)
k (Wm-1K-1) (ndot ~7×1020 cm-3)
Melting temp. (°C)
Yb:YAG
9 ( ↔ 124 fs)
7.5
1940
Yb:Lu2O3
13 ( ↔ 87 fs)
12.3
2400
Dlem FWHM (nm)
k (Wm-1K-1) (ndot ~7×1020 cm-3)
Melting temp. (°C)
Yb:YAG
9 ( ↔ 124 fs)
7.5
1940
Yb:Lu2O3
13 ( ↔ 87 fs)
12.3
2400
Yb:CALGO
62 ( ↔ 18 fs) 4
1840
Pulse duration
30 fs
Output power
150 mW
Spectral bandwidth FWHM
45 nm
GDD per RT
-1000 fs²
Output coupling rate
0.3 %
TBP (ideal sech2: 0.315)
0.369
Opt-to-opt efficiency
0.1 %
Ytterbium doped Calcium Gadolinum Aluminate: Yb:CaGdAlO4: Yb:CALGO
Submitted to Optics Letters
*inversion level: 0.1

10. Conclusions and outlook
Conclusions and outlook
Key for short pulse generation
First Yb:CALGO KLM TDL
Combination of:
Thin-disk laser oscillator
Kerr lens mode locking
Broadband gain material
*inversion level: 0.1
Record performances from an Yb-based oscillator
Shortest pulses from Yb-doped bulk and thin-disk lasers
Yb:Lu2O3 [1]
Yb:CALGO [2]
Highest average power from any oscillator in sub-50-fs pulses
[1] C. Paradis et al., Opt. Express 25, 14918–14925 (2017).
[2] submitted to Optics Letters
Wavelength conversion
Frequency comb generation
Applications
Powerful sub-50-fs pulses
Apply KLM scaling laws
Broadband optical coating optimization
Optimize disk quality and parameters

11. Thank you for your attention
Acknowledgments
Thank you for your attention
UniNE LTF group