Continuum “White Light”

Generation

WhiteLase: High Power Ultra-

broadband Light Sources

Technology

Ultrafast Pulses + Fiber Laser + Non-linear PCF

= Spectral broadening from 400nm to 2500nm

Ultrafast Fiber Laser MOPA

• MOPA = Master Oscillator Power Amplifier

• All fiber design – no free-space optics

• In supercontinuum systems “post processing” is non-linear microstructured optical fiber (PCF)

Master Oscillator

• Diode pumped Yb fiber laser at 1064nm

• Passively mode-locked via saturable absorber mirror

• Self-starting operation providing transform limited pulses – 3ps (min) to >100ps (max)

• Repetition rate set by fiber length: – 20MHz (min) to ≈110MHz (max)

Changing Repetition Rate

5

•Repetition Rate

20MHz

•Pulse energy ≈100nJ

•Average Power 2W

•pulse-pulse: 50ns

•Repetition Rate

10MHz

•Pulse energy ≈100nJ

•Average Power 1W

•pulse-pulse: 100ns

•Repetition Rate

6.67MHz (custom)

•Pulse energy ≈100nJ

•Average Power

667mW

•pulse-pulse:150ns

•Repetition Rate

5MHz

•Pulse energy ≈100nJ

•Average Power

500mW

•pulse-pulse: 200ns

I

t

I

t

I

t

PCF

t

Amplifier Pulse-

picker

Master

Oscillator

Supercontinuum Generation

• Spectrum related primarily to the Kerr and Raman non-linearities

• Raman scattering, Self Phase Modulation (SPM) and Four-wave mixing (FWM) involved

• Pump needs to be close to the zero-dispersion of the fiber in the anomalous regime

• High peak-power is maintained and the fiber non-linearity can be maintained over long interaction lengths

• Result is spectral broadening in both directions around the pump wavelength

Photonic Crystal Fiber (PCF)

• Microstructured fiber with solid silica

core and air/silica cladding

• High difference in refractive index

between core and cladding guides

light

– Single spatial mode at all wavelengths

– Small core-size enhances non-linear

effects

• Group Velocity Dispersion properties

can be carefully designed

7

Peak Power Drives Spectral Bandwidth

Peak Power Drives Spectral Bandwidth

Peak Power Drives Spectral Bandwidth

Peak Power Drives Spectral Bandwidth

Peak Power Drives Spectral Bandwidth

Peak Power Drives Spectral Bandwidth

Peak Power Drives Spectral Bandwidth

Peak Power Drives Spectral Bandwidth

Supercontinuum Laser Evolution

2005 2008 2010 2013 1W 6W >10W 4W

• Over the last 7 years, SC lasers have seen an order of magnitude

increase in their output powers.

• Market demands and technology developments are driving product

evolution in three key directions:

– Higher power

– More spectral bandwidth

– Lower cost / higher reliability

Higher Power Supercontinuum

• Spectrum is determined by the peak power of pump pulses.

• By increasing the repetition rate of the oscillator, the supercontinuum power

increases while the spectrum is fixed.

• Current state-of-art SC has >10W average power with >1.5W in the visible

range.

• Short term experiments (200h) performed at much higher powers of 30W

(5W visible power) have suggested significant power scaling is still

achievable using current technology...

10W laser

1.5W

visible

Limitations of Supercontinuum Lasers

• Photodarkening of fibers was historically a problem.

• Generation of deeper UV wavelengths inside fiber causes photodarkening.

• Proprietary fiber design can reduce photodarkening and enables SC systems capable

of operating at higher power levels and UV wavlengths…to a limited extent

• Further power scaling may involve combining multiple SC sources into a single high

power output of reduced “brightness”.

• Deeper UV wavelengths can be achieved by harmonically doubling SC output.

• Reliability of “youthful” technology.

Properties of Supercontinuum Light

• Broadband pulsed output

– Typically ≈2µm bandwidth

– Continuously bright spectrum with no “gaps”

• “Laser-like” beam propagation

– Collimated output

– Can be steered/manipulated like a laser

• Single spatial mode at all wavelengths

– Can be efficiently fiber-coupled

– Can be focused to diffraction-limited spot

– High brightness compared to other BB sources

• Ultrafast pulses at high repetition rate

– Can be used as Quasi-Continuous Wave source

– Can be used for lifetime study (≈50ps filtered pulse-width)

• Low temporal coherence – can be used for OCT

Applications

• Fluorescence excitation

• Industrial inspection and sorting

• Lifetime study

• Super-resolution techniques

• Medical illumination

• Broadband spectroscopy

• Nanophotonics

• Optical Coherence Tomography

• Hyper-spectral measurement

• Raman spectroscopy

• High intensity lamp replacement

Future Developments

• UV Supercontinuum – High Power <390nm

– Low Power <350nm

• Average Power Scaling – 10W supercontinuum released in 2012

– 30W supercontinuum demonstrated in lab

• Lower Repetition rates – Project to develop single-shot to 80MHz source

• Femtosecond Supercontinuum – Pumping PCF with femtosecond 1064nm laser source

Thank you

info@fianium.com

Tim Gerke

tim.gerke@fianium.com

direct: 720-341-2784

Fianium WhiteLase

Compact mode-locked supercontinuum lasers

WhiteLase micro

ALP (Advanced Laser Platform)

WhiteLase SC400, SC450 & SC480

WhiteLase micro

• Spectrum from <450nm to >2000nm

• >200mW total output power (>20mW visible)

• 20MHz repetition rate

-40

-30

-20

-10

0

10

400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200

Spectral power density (dBm/nm)

Wavelength (nm)

WhiteLase SC400 & SC450

0

1

2

3

4

5

6

7

300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500

Spectral Power Density (mW/nm)

Wavelength (nm)

SC400-6

SC400-4

SC400-2

WhiteLase SC450-HE

• Optimised for maximum supercontinuum pulse energy

• 1nJ/nm from 600-800nm

• Full Spectrum from <550nm to >1750nm

• Operates at 1MHz and 0.5MHz – user selectable

• Super-resolution and spectroscopy applications

0

1

2

3

400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 Spectral power desnity (nJ/nm)

Wavelength (nm)

SC390 UV-Enhanced

• Short-wavelength

cut-in <390nm –

shortest available

• Long wavelength

edge ~2400nm

• Up to 3W total

power

Acousto-Optic Tunable Filter

AOTF-DUAL

• Dual output filter module to cover extended wavelength range

• Can cover any two standard AOTF wavelength options

AOTF-HP

• New high-power version of Fianium AOTF system

• Provides >70% of supercontinuum power density to free-space unpolarised beam

AOTF • Removable tunable filter compatible

with all Fianium WhiteLase™ Supercontinuum Systems

• Up to 8 collinear individually tunable channels

• Three wavelength options covering full spectral range : 400-700nm, 650-1100nm & 1100-2000nm

SuperChrome™ Tunable Filter

Tunable Wavelength

• Single channel tunable from 400nm to 850nm

• Broadband “White Light” setting

Tunable Bandwidth

• <5nm to >50nm FWHM tunability

• Optimise channel bandwidth vs. output power

High Performance

• Up to 50dB out-of-band

suppression

• 80% transmission

• Fast 100nm/s tuning speed

• High beam quality

• Free-space or FC fiber delivered

output