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.

Time-Bandwidth ProductsTime-Bandwidth Products getting the average power of ultrafast DPSS getting the average power of ultrafast DPSS lasers from hundreds of mW to tens of Wattslasers from hundreds of mW to tens of Watts

by Dr. Thomas Ruchti

CERN, April 2006

SESAMSESAM®® Ultrafast Ultrafast

2

TBP – a thriving company from a thriving city

3

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

4

Typical pulse energy vs. repetition rate graph for ultrafast lasers in the late 90’ies

oscillator domainlow energy

amplifier domainlow speed

100 W10 W

1 W

100 mW10 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

Pu

lse

en

erg

y

TBP products in the 90ies

TBP products in the 90ies

5

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 increasedSESAM acts in reflectivity Nonlinear reflectivity:

10-5

2

4

10-4

2

4

Transm

issio

n,

a.u

.

1050

Time Delay, ps

long 10 ps

short 350 fs

Temporal response:100.0

99.8

99.6

99.4

99.2

99.05 6 7 8

1002 3 4 5 6 7 8

10002 3

Pulse fluence on SESAM (µJ/cm2)

nonsaturable losses

R

Fsat,A

Nonlinear reflectivity:

Non

linea

r re

flect

ivity

Time delay (ps)Pulse fluence of SESAM (µJ/cm2)

basic parameters adjustable by:operation wavelength L semiconductor compound Egap

modulation depth R absorber thickness, top reflector saturation fluence Fsat Egap, top reflector

response time A growth temperature, annealing saturation energy Esat beam radius A and Fsat

Rns

R>99.5%

Saturable Absorber / spacer layer

Semiconductor Bragg mirror

Incident light

6

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 / customizableRepetition rate can be locked to a reference RF with high precision,

jitter typically <200fs

Typical microwave spectrum of Lynx laser

7

New high power oscillator introduced by Time-Bandwidth Products AG

oscillator domainlow energy

amplifier domainlow speed

100 W10 W

1 W

100 mW10 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

Pu

lse

en

erg

y

TBP products in the 90ies

TBP products in the 90ies

10W TBP oscillator

8

TBP oscillators product range

Pulse durations 60 fs – 500 ps

Pulse energies up to 200 nJ

Repetition rates up to 10 GHz

Wavelengths 260 nm – 1550 nm

9

Higher pulse energy at higher repetition rates

oscillator domainlow energy

amplifier domainlow speed

100 W10 W

1 W

100 mW10 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

Pu

lse

en

erg

y

TBP products in the 90ies

TBP products in the 90ies

10W TBP oscillator

10

High power / high pulse energy ps amplifierWhy 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

12ps

J to mJ

Hz to MHz

Nd:VAN Nd:VAN

11

Product Portofolio ReviewHigh Pulse Energy Laser Products

Jaguar laser models DUETTOTM laser model

System description: regenerative amplifier MOPARepetition rate: single shot up to 4kHz 50kHz – 8MHzFundamental wavelength: 1047/1053/1064nm 1064nmPulse width: 10ps to 500ps 11ps ±3ps or longerOutput power: up to 2W ≥ 10WPulse energy: up to 1.5mJ depends on rep rate, ie 100JPeak power: up 150MW up to 16MW

12

New generation high power / pulse energy ps amplifier

oscillator domainlow energy

amplifier domainlow speed

100 W10 W

1 W

100 mW10 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

Pu

lse

en

erg

y

TBP products in the 90ies

TBP products in the 90ies

10W TBP oscillator

DUETTO™

13

The technique behind FORTIS™ - a fruitful

combination Thin-disk laser head SESAM®

High power with perfect beam quality

Stable and reliable passive mode locking

Sub-picosecond pulses with highest average power

perfect match

14

• 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 TEM00 operation

The technique behind FORTIS™: thin-disk lasers

Heat sink

1D longitudinalheat flow

Laser medium

AR coatingHR coating

Pump light

Laser mode

A. Giesen et al., Appl. Phys. B 58, 363 (1994).

15

The technique behind FORTIS™: SESAM®

technology

Gain

Outputcoupler

End mirror

Saturable absorber: lower losses for higher intensities

16

The technique behind FORTIS™: SESAM®

technology

Gain

Outputcoupler

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

Outputcoupler

17

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

M2 (TEM00)

Cutting-edge performance from an oscillator-only design – no amplifier!

18

datafit

p = 750 fs

Delay (fs)

Inte

nsity

(a.

u.)

Inte

nsity

(a.

u.)

Wavelength (nm)

datafit

= 1.6 nm

Distance (mm)

Bea

m s

ize

(mm

) datafit

M2 < 1.1

FORTIS™ - excellent temporal, spectral, and spatial

pulse qualitytemporal: Autocorrelation spectral: Optical spectrum

spatial: M2

19

New generation high power / pulse energy ps amplifier

oscillator domainlow energy

amplifier domainlow speed

100 W10 W

1 W

100 mW10 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

Pu

lse

en

erg

y

TBP products in the 90ies

TBP products in the 90ies

10W TBP oscillator

DUETTO™

FORTIS™

20

Interested?

visit us at www.time-bandwidth.com

21

TBP – a thriving company from a thriving city