Time-Bandwidth Products getting the average power of ultrafast DPSS lasers from hundreds of mW to tens of Watts by Dr. Thomas Ruchti CERN, April 2006 SESAM ® Ultrafast

1 TBP – a thriving company from a thriving city

2 History Time-Bandwidth Products AG was founded at the end of 1994 as spin of from the Federal Institute of Technology (ETH) in Zurich First commercial products did ship in 1996 At that time: a few hundred of mW output power from a fs / ps laser was considered as astonishing, ie: -GLX-200: 150fs with 100mW output power -GE-100: 8ps with 300mW output power Today, 10 years later, we sell commercial products with several Watts of output power

3 Typical pulse energy vs. repetition rate graph for ultrafast lasers in the late 90’ies oscillator domain low energy amplifier domain low speed 100 W 10 W 1 W 100 mW 10 mW 1 kHz 10 kHz 100 kHz 1 MHz 10 MHz 100 MHz Repetition rate 1 mJ 100 µJ 10 µJ 1 µJ 100 nJ 10 nJ 1 nJ Pulse energy TBP products in the 90ies

4 SESAM ® device acts as saturable absorber saturable absorber introduces less loss into a laser cavity at higher energy densities (fluences) than at low fluences laser operates in pulsed mode by itself (passive pulsing), as net gain is increased SESAM acts in reflectivity  Nonlinear reflectivity: Temporal response: Nonlinear reflectivity: Nonlinear reflectivity Time delay (ps)Pulse fluence of SESAM (µJ/cm 2 ) basic parameters adjustable by: operation wavelength L semiconductor compound E gap modulation depth  R absorber thickness, top reflector saturation fluence F sat E gap, top reflector response time  A growth temperature, annealing saturation energy E sat beam radius A and F sat R ns

5 Key points of passively mode-locked DPSS lasers using SESAM ® technology Very low amplitude noise, typically <0.1% rms All diode pumped solid state -Very compact packages possible -No fast degeneration of SESAM – substantial investment over the last >10 years in basic device research No pre- and/or post pulses as often seen with actively mode-locked systems -No active control/switching required Reliable self starting mechanism SESAM device is the end mirror of the laser cavity -Repetition rate of the laser: F = c/(2xL), ie 100MHz => 1.5m high flexibility / customizable Repetition rate can be locked to a reference RF with high precision, jitter typically <200fs Typical microwave spectrum of Lynx laser

6 New high power oscillator introduced by Time-Bandwidth Products AG oscillator domain low energy amplifier domain low speed 100 W 10 W 1 W 100 mW 10 mW 1 kHz 10 kHz 100 kHz 1 MHz 10 MHz 100 MHz Repetition rate 1 mJ 100 µJ 10 µJ 1 µJ 100 nJ 10 nJ 1 nJ Pulse energy TBP products in the 90ies 10W TBP oscillator

7 TBP oscillators product range Pulse durations60 fs – 500 ps Pulse energies up to 200 nJ Repetition rates up to 10 GHz Wavelengths260 nm – 1550 nm

8 Higher pulse energy at higher repetition rates oscillator domain low energy amplifier domain low speed 100 W 10 W 1 W 100 mW 10 mW 1 kHz 10 kHz 100 kHz 1 MHz 10 MHz 100 MHz Repetition rate 1 mJ 100 µJ 10 µJ 1 µJ 100 nJ 10 nJ 1 nJ Pulse energy TBP products in the 90ies 10W TBP oscillator

9 High power / high pulse energy ps amplifier Why even consider to do a ps amplifier and not a fs amplifier? In the past a lot of research in material processing with fs TiSA amplifiers: Good results but too complex and too low repetition rate: Typical fs TiSA amplifier layout: TiSA seed laser 80MHz, nJ, 100fs Stretcher fs to ns TiSA amplifier (regen or CPA),  J to mJ Hz to kHz Q-switched green Pump laser ns, mJ, Hz to kHz Compressor ns to fs <150fs  J to mJ Hz to kHz Typical ps amplifier system is much simpler and therefore more reliable and easier to use Higher output power Higher repetition rate No stretcher and compressor, no Q-switched green pump laser ps amplifier by TBP: 12ps  J to mJ Hz to MHz Nd:VAN

10 Product Portofolio Review High Pulse Energy Laser Products Jaguar laser modelsDUETTO TM laser model System description:regenerative amplifierMOPA Repetition rate:single shot up to 4kHz50kHz – 8MHz Fundamental wavelength:1047/1053/1064nm1064nm Pulse width:10ps to 500ps11ps ±3ps or longer Output power:up to 2W≥ 10W Pulse energy:up to 1.5mJdepends on rep rate, ie 100  J Peak power:up 150MWup to 16MW

11 New generation high power / pulse energy ps amplifier oscillator domain low energy amplifier domain low speed 100 W 10 W 1 W 100 mW 10 mW 1 kHz 10 kHz 100 kHz 1 MHz 10 MHz 100 MHz Repetition rate 1 mJ 100 µJ 10 µJ 1 µJ 100 nJ 10 nJ 1 nJ Pulse energy TBP products in the 90ies 10W TBP oscillator DUETTO™

12 The technique behind FORTIS™ - a fruitful combination Thin-disk laser headSESAM ® High power with perfect beam quality Stable and reliable passive mode locking Sub-picosecond pulses with highest average power perfect match

13 Laser medium in geometry of a thin disk (≈0.1 mm) Mode diameter larger than disk thickness  longitudinal quasi-1D heat flow  reduction of thermal lens and aberrations  enables high-power TEM 00 operation The technique behind FORTIS™: thin-disk lasers Heat sink 1D longitudinal heat flow Laser medium AR coating HR coating Pump light Laser mode A. Giesen et al., Appl. Phys. B 58, 363 (1994).

14 The technique behind FORTIS™: SESAM ® technology Gain Output coupler End mirror Saturable absorber: lower losses for higher intensities

15 The technique behind FORTIS™: SESAM ® technology Gain Output coupler SESAM ® SEmiconductor Saturable Absorber Mirror U. Keller et al., Opt. Lett. 17, 505 (1992) all-solid-state adjustable absorber parameters self-starting, stable, and reliable mode locking Output coupler

16 FORTIS™ - mode-locked laser with highest power on the market 50 W 40 – 60 MHz 1 µJ < 850 fs 1 MW 1030 nm 1.1 output power repetition rate pulse energy pulse width peak power wavelength M 2 (TEM 00 ) Cutting-edge performance from an oscillator-only design – no amplifier!

17 data fit  p = 750 fs Delay (fs) Intensity (a.u.) Wavelength (nm) data fit  = 1.6 nm Distance (mm) Beam size (mm) data fit M 2 < 1.1 FORTIS™ - excellent temporal, spectral, and spatial pulse quality temporal: Autocorrelationspectral: Optical spectrum spatial: M 2

18 New generation high power / pulse energy ps amplifier oscillator domain low energy amplifier domain low speed 100 W 10 W 1 W 100 mW 10 mW 1 kHz 10 kHz 100 kHz 1 MHz 10 MHz 100 MHz Repetition rate 1 mJ 100 µJ 10 µJ 1 µJ 100 nJ 10 nJ 1 nJ Pulse energy TBP products in the 90ies 10W TBP oscillator DUETTO™ FORTIS™

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20 TBP – a thriving company from a thriving city