Development and Implementation of Near- Infrared Ultrafast ... Final... · Infrared Ultrafast Laser...

Development and Implementation of Near-

Infrared Ultrafast Laser Sources Generated by

Nonlinear Fiber Propagation

Final Exam for Scott R Domingue, PhD candidateDepartment of Electrical and Computer Engineering

Colorado State University

Welcome to my committee members:

Prof. Amber Krummel

Prof. Diego Krapf

Prof. Mario Marconi

and my adviser

Prof. Randy Bartels

Development and Implementation of Near-

Infrared Ultrafast Laser Sources Generated by

Nonlinear Fiber Propagation

Final Exam Overview:Examining a couple systems utilizing our 1060 nm

ultrafast technology for an end-goal application

Imaging ModalityNonlinear Optical

ElementUltrafast Sources

ANDi fiber Laser

3-Photon

Excitation

Fluorescence

Hyperspectral

Imaging via

Excitation Labeled

Fluorescence

ANDi seeded NPA

Dual-Band SC

ANDi: all normal dispersion laser

NPA: nonlinear power amplifier

SC: supercontinuum generation

Part I

Part III

Part IINonlinear Pulse

Compression w/

Normal Dispersion SC

Second-Harmonic

Generation

• (I) Chapter 6

• (I) Chapter 7

• (II) Chapter 10

• (III) Chapter 14

Multi-Photon Microscopy based on Labels,

Endogenous Fluorophores, and Harmonic-

Generation Imaging

Laser-scanning, multi-photon microscopy:

• High Resolution (submicron)

• Optical Sectioning

• Imaging Through Scattering media

(scattering dominated attenuation, 𝜆−2 −𝜆−4)

Recent Advances: Quantitative diagnosis of

disease based on label-free tissue interrogation

• 2nd-harmonic generation from collagen:

quantification of fibrosis

• 2-photon excitation fluorescence from

intrinsic fluorophores: metabolic response

from NADH concentration

• 3rd-harmonic generation from lipids:

functional imaging of retinas (𝜏−2 signal

sensitivity)

Denk, W.et al., Science 248, (1990)

Campagnola, P., Anal. Chem. 83, (2011)

Xu, C. et al., Proc. Natl. Acad. Sci. 93, (1996)

Masihzadeh, O. et al., Mol. Vis. 21, (2015)

Part IIntro.

Experimental Super-Resolved Multiphoton

Microscopy with Spatial Frequency-Modulated

Imaging

Field, JJ, et al., ARXIV, (2015)

Second-harmonic

generation from CdTe

Solar Cell grain

boundaries

Two-photon auto-

fluorescence (or

photoluminescence)

Increased Resolution

Line Focus => average

power limitations

Part IIntro.

Scaling Relationships between

Excitation Pulses and nonlinear signal

level

power in Nth-order nonlinear

signal, from pulses with intensity

𝐼 𝑡 and repetition rate 𝑓𝑊 ∝ 𝐼𝑁 = 𝑓∫ 𝐼 𝑡

𝑁𝑑𝑡

𝑊 ∝𝐼 𝑁

𝑓𝑁−1 𝜏𝑁−1

Scaling the power in Nth-order nonlinear signal with excitation pulse

parameters (for clean, Gaussian pulses)

𝐼 : Average Power

𝜏 : Pulse Duration

𝑓 : Pulse Repetition Rate

𝐼 𝑡 =𝐼

𝑓𝜏 𝜋𝑒−

𝑡𝜏

2

Part IIntro.

The Color Spectrum of Multi-Photon

Imaging ModalitiesHow might we access the extensive color palette of ultrafast microscopy starting with

1060 nm pulses? (Answer: Harnessing nonlinear propagation)

500 750 1000 1250 1500 1750 2000

Ti:SapphireYb-dopedEr-dopedCr:Forsterite

Wavelength [nm]

Imaging

Modalities

2nd and 3rd Harmonic GenerationSHG/ THG

2-PEF 3/4-PEF

CRS

TAS Transient Absorption Spectroscopy

Coherent Raman Spectroscopy

2-, 3-, and 4-Photon Excitation Fluorescence

Ultrafast

Sources

Part IIntro.

Nonlinear Bulk

and Fiber based

Extensions

A-SC

DB-SCDB-SC

A/N-SC

SSFS

Dual-Band Supercontinuum

Supercontinuum (Normal vs. Anomalous Dispersion)

Soliton Self-Frequency Shifting

OPO Optical Parametric Oscillator

A-SC

How might we access the extensive color palette of ultrafast microscopy starting with

1060 nm pulses? (Answer: Harnessing nonlinear fiber propagation)

Imaging

Modalities

2nd and 3rd Harmonic GenerationSHG/ THG

2-PEF 3-PEF

CRS

TAS Transient Absorption Spectroscopy

Coherent Raman Spectroscopy

2-, 3-Photon Excitation Fluorescence

500 750 1000 1250 1500 1750 2000

Wavelength [nm]

Yb-doped fiber lasers

Supporting ~150 fs pulses

Nonlinear Fiber

Based Spectral

Solutions for 1060

nm pulses

DB-SCDB-SC

N-SC

Dual-Band Supercontinuum

Normal Dispersion Supercontinuum

Leveraging Nonlinear Fiber Propagation to

Extend the Application Space of Yb-doped laser

Part IIntro.

Our Goals for 1060 nm Ultrafast Source Development via Nonlinear Pulse Compression

Part IIntro.

1060 nm sources

beyond the Yb

gain bandwidth

750 1000 1250



N-SC

Wavelength [nm]

Normal Dispersion

Supercontinuum

1. Bandwidths/Durations comparable to Ti:Sapphire Oscillators: <30 fs2. Average Powers/Pulse Energies sufficient for creative microscope

development: >0.5 W / >10 nJ

3. High quality pulse intensity profiles: >90% Normalized Compression

4. Stability and Reliability exceeding that of Ti:Sapphire Oscillators: up-time

of Months to Years

5. Simplest (most elegant) possible optical systems: price point low enough

for system replication

6. High Quality Power Spectra: power spectral smoothness comparable to

Gaussian Pulses

Our Starting Ultrafast Source at 1060 nm

ANDi

`

NPA

`

`

MC

Master Oscillator Nonlinear and Power Amplifier, using Yb-doped

optical fiber

• 27 nJ or 1.7 W at 63

MHz

• 136 fs FWHM, 180 kW

peak power

• 97% of TL peak powerMaster Oscillator Nonlinear and Power Amplifier



MC: Martinez compressor

1045 1065 10850

0.2

0.4

0.6

0.8

1

Pow

er S

pec

trum

[a.

u.]

Wavelength [nm]-200 0 200

0

0.2

0.4

0.6

0.8

1

Time [fs]

Inte

nsi

ty [

a.u

.]

Part IInitialSource

Domingue, S. R. et al., Opt. Lett. 39, (2014)

850 950 1050 1150 1250-200

-150

-100

-50

0

50

Wavelength [nm]D

isper

sion C

oef

fici

ent

[ps/

nm

-km

]

Bulk FSLMA-PM-10, PCFLMA-PM-5, PCF

SC-4-975, PCFNL-1050-NEG1, PCF

UHNA3

Spectral Broadening in Optical Fiber

ANDi

`

NPA

`

`

MC

SC

Generating shorter pulses from the Yb-doped ultrafast source, using

nonlinear propagation in optical fiber





solitons

𝛽2 = −𝐷10−6𝜆2

2𝜋𝑐Conversion to Group

Velocity Dispersion

Part INonlinearPulseCompression

`

MC

1060 nm

Our Early Lessons in Nonlinear Pulse Compression

ΦRSN

RMS-N

RSN

S.R. Domingue et al., Optics Express 21 (2013)

What we thought we knew• PM nonlinear fiber => eliminates polarization

instability AND average power limitations

Yb:KYWPulse Shaper +

Grating

Compressor

SC in Normal

Dispersion, “Fairly”

nonlinear fiber

• Pulse shaper + prism compressor => a general

solution to nonlinear pulse compression

Non-PM PM


350 mW

Transmissive Pulse Shaping in the Naïve limit

Transform-Limit supported by the SC bandwidth dropped

from 18(dashed) to 36 fs (solid)

None of which are the Dominant Issue

Initially attributed to sub-optimal pulse shaper: visible SLM, 4λ SLM

Wavefront Error, Spherical Aberration, and Spatial Chirp

Wav

elen

gth

[n

m]

Time [fs]

Mea

sure

d

Rec

on

stru

cted

-100 0 100

490

500

510

520

530950 1000 1050 1100

0

0.2

0.4

0.6

0.8

1

1.2

Pow

er S

pec

tru

m [

a.u

.]

Wavelength[nm]

SeedSC

-1000 0 10000

0.5

1

Inte

nsi

ty [

a.u

.]

Time [fs]

SeedSC

-1

0

1

2

Sp

ectr

al P

has

e [r

ad]


SLM: spatial light modulator

930nm990nm1060nm

1150nm

1230nm

4-F Martinez Pulse Shapers with an Achromatic Doublet

Extensive Petzval Field Curvature, roughly quadratic in Field Angle (i.e.

Diffraction Angle / Wavelength)

-10 -5 0 5 10

-14

-12

-10

-8

-6

-4

-2

0

Field Angle, Δθ [degrees]

Fie

ld C

urv

ature

[m

m]

170nm

302nm15fs

127nm

224nm20fs

102nm

179nm

25fs

72nm

127nm

35fs

51nm

89nm

50fs

Rayleigh

Lengths

S.R. Domingue et al., Optics Letters, 40 (2015)

Out of Plane Focusing =>

Spectral Wings are NOT 4-F =>

Spectral Apodization

sin 𝛾 − sin 𝜃 𝜆 = 𝑁𝜆

Δ𝜃 = 𝜃 𝜆 − 𝜃(𝜆0)

950 1000 1050 1100Pow

er S

pec

trum

[a.

u.]

Wavelength [nm]

Trans. Grating


4-F Martinez Pulse Shapers with a Plӧssl Lens

Significant reduction in Petzval Field Curvature


A. Negrean et al., Biomed. Opt. Express. 5, (2014)

= 𝑧𝑡𝑎𝑛 (𝜆)

𝑧𝑅𝑎𝑦𝑙𝑒𝑖𝑔ℎ 𝜆∗ 100 %

Tangential

Relative

Curvature0 2 4 6 8 10 12

-10

-8

-6

-4

-2

0

Field Angle [degrees]

Tan

gen

tial

Rel

ativ

e

Cu

rvat

ure

[100%

]

Wavelength [nm]

60mm Plӧssl100mm Plӧssl

200mm Ach.

150mm Ach.

100mm Ach. same as before

75mm Ach.

1060 1089 1117 1145 1171 1197 1222Flat-Field Pulse Shaper

930nm990nm1060nm

1150nm

1230nm

Trans. Grating

Kernel for Idea:

Swap grating for Scan Mirror (galvo)

and it’s a Laser Scanning system,

Plӧssl lenses are nearly telecentric.


ANDi

`

NPA

`

`

MC

SC

Armed with the Flat-Field Pule shaper, we try to use the Master Oscillator Nonlinear

and Power fiber Amplifier to generate broader bandwidths

Pulses injected into SC fiber

• 27 nJ or 1.6 W at 60 MHz

• 136 fs FWHM

• 97% of TL peak power

Notice: ~1 W coupled

power vs. 0.35 W before





FFPS: flat-field pulse shaper

So what happens in

“fairly” nonlinear PM

fiber (more nonlinear than

telecom fiber) at these

higher pulse energies?

`

FFPS


Nonlinear Pulse Compression beyond the Naïve limit (almost)

The PM, “fairly” nonlinear fiber fails

The polarization

maintenance fails after

~30 min exposure of

500 mW average

power

ANDi

`

NPA

`

`

MC

SC






`

FFPS

Similar failure reports

in PM photonic

crystal fiber.


Nonlinear Pulse Compression beyond the Naïve limit (almost)

-150 -100 -50 0 50 100 1500

0.2

0.4

0.6

0.8

1

Time [fs]

Inte

nsi

ty [

a.u

.]

0

10

20

30

40

Sp

ec.

Ph

ase

[rad

]

980 1030 1080 1130

Wavelength [nm]

State-of-the-Art Nonlinear Pulse Compression

`

ANDi

`

NPA

`

MC

SC

Master Oscillator Nonlinear and Power fiber Amplifier + Telecom-like fiber (low

nonlinearity) + Flat-Field Pulse Shaper:

ANDi: all normal dispersion laserNPA: nonlinear power amp.MC: Martinez compressorSC: supercontinuum generationFFPS: flat-field pulse shaperTL: transform-limited duration

Move away from “nonlinear” fiber and

towards telecom and amplifier fibers: 𝛾𝑁𝐿

∼3

`

FFPS

FFPS

TL

27 fs

FWHM

State-of-the-Art

at 10 nJ

Shaper-off

Fiber

Shaper-on



0 2.5 5 7.5 10 12.50

5

10

15

20

25

SLM Pixel [k-pix.]

Vo

ltag

e B

its

[k-b

its]

0

10

20

30

40

50

0

0.2

0.4

0.6

0.8

1

What Sources hath Nonlinear Pulse Compression wrought?

Generating state-of-the-art pulses beyond the typical Yb-doped gain bandwidth

using our series of pulse source and pulse shaping technologies

S.R. Domingue et al., Optics Letters, 40 (2015)TL: transform-limited duration


950 1000 1050 1100 1150 1200

0

10

20

30

40

50

Wavelength [nm]

Spec

tral

Phas

e [r

ad]

-80 -60 -40 -20 0 20 40 60 800

0.2

0.4

0.6

0.8

1

Time [fs]

Inte

nsi

ty [

a.u

.]

95 % TL

27 fs

FWHM

FFPS

TL

Shaper-off

Fiber

Shaper-on

10

0 m

m P

lӧss

l

92 % TL

19 fs

FWHM

60

mm

Plӧ

ssl 10 nJ

600 mW

Revisiting Our Goals for 1060 nm Ultrafast Source Development via Nonlinear Pulse

Compression1060 nm sources

beyond the Yb

gain bandwidth

750 1000 1250

Yb-doped fiber lasersSupporting ~150 fs pulses

N-SC

Wavelength [nm]


1. Bandwidths/Durations comparable to Ti:Sapphire Oscillators: <30 fs2. Average Powers/Pulse Energies sufficient for creative microscope

development: >0.5 W / >10 nJ

3. High Quality Pulse Intensity profiles: >90% Normalized Compression

4. Stability and Reliability exceeding that of Ti:Sapphire Oscillators: up-time

of Months to Years




Gaussian Pulses

Part IFinale

Revisiting Our Goals for 1060 nm

ultrafast source development1060 nm sources beyond

the Yb gain bandwidth

750 1000 1250



N-SC

Wavelength [nm]





Gaussian Pulses

Part IFinale

`

AN

Di `

MC

2 W

ANDi

Spectral Clipping

Enclosed Short

(<50 mm)

Photonic Crystal

Fiber

(Hyper) Prism

Compressor

Without a Pulse

Shaper

> 10 nJ

< 20 fs

1 MW Peak Power

• Chapter 2.3

• Chapter 4.3

• Chapter 6.3

• Chapter 10

Moving from Source Development to Applications

Some possible applications utilizing our ultrafast 1060 nm pulse source, in

particular the two that we describe in remainder of the presentation.

`

ANDi

`

NPA

`

MC

SC


NPA: nonlinear power amp.




`

FFPS

• ~25 fs

• >350 kW

• 10 nJ @ 60 MHz

• 600 mW

`

Laser Scanning

Multi-photon

Microscopy

`Nonlinear Laser

Machining

`

3-Photon

Excitation

Fluorescence

Microscopy

`

Hyperspectral

Imaging via

Excitation Labeled

Fluorescence

`

Nonlinear 1250

nm pulse

generation`

Second

Harmonic

Generation

Part IFinale

Part IPart III Part II

Motivation for Part II: Source Development in the 1300 nm Biological Imaging Window

The attenuation of ballistic photons with propagation in turbid

(biological) media fundamentally limits the depth of image penetration

for multi-photon microscopy.

800 1000 1200 1400 1600 18000

250

500

750

1000

1250

1500

1750

Att

enu

atio

n L

eng

th [

μm

]

Wavelength [nm]

Mie Scattering

Water Absorption

Combined (Mouse

Cortex Model)

𝑙𝑒 =1

𝑙𝑠𝑐𝑎𝑡𝑡𝑒𝑟𝑖𝑛𝑔+

1

𝑙𝑎𝑏𝑠𝑜𝑟𝑝𝑡𝑖𝑜𝑛

−1

Effective multi-photon fluorescence

attenuation length (depth where signal

decays by 𝑒−2)

D. Kobat et al., J. Biomed. Opt. 16, (2011)

N.G. Horton et al., Nat. Photonics 7, (2013)

Fundamental image penetration

depth limit (in-focus fluorescent

signal to background ratio >1):

• 2-photon excitation ~5-6× 𝑙𝑒• 3-photon excitation ~8-9× 𝑙𝑒

Part IIIntro.

Motivation for Source Development in the 1300 nm Biological Imaging Window

To reach the fundamental depth limit, you do still need enough average

power (and/or pulse energy) to get ballistic photons down to 5𝑙𝑒

800 1000 1200 1400 1600 18000

250

500

750

1000

1250

1500

1750

Att

enu

atio

n L

eng

th [

μm

]

Wavelength [nm]

Mie Scattering

Water Absorption

Combined (Mouse

Cortex Model)

Canonical Ultrafast Lasers

Early Work• Ti:sapphire, 830 nm

• 𝑙𝑒 = 155 𝜇m

• Maximum Imaging Depth =

650 𝜇m (~4𝑙𝑒 ≠ 5𝑙𝑒)

D. Kleinfeld et al., Proc. Natl. Acad. Sci. 95, (1998)

J. Mertz, Introduction to Optical Microscopy, (2009)

• Reducing 𝜏 is limited to ~5x

• Instead reduce f by ~500x

𝑊 ∝𝐼 𝑁

𝑓𝑁−1 𝜏𝑁−1

Part IIIntro.

To reach the fundamental depth limit, you do still need enough average

power (and/or pulse energy) to get ballistic photons down to 5𝑙𝑒

Canonical Ultrafast Lasers

Later Work• Ti:sapphire, 925 nm

• 𝑙𝑒 = 200 𝜇m

• Regenerative amplifier: 200 kHz

repetition rate (150 fs, 3 𝜇J

pulses)

• Imaging GFP-labeled neurons

1 mm below brain surface (5𝑙𝑒)

P. Theer et al., OL 28, (2003)

This hits the limit of penetration

depth. To get deeper have to

scale something else… 𝜆800 1000 1200 1400 1600 18000

250

500

750

1000

1250

1500

1750

Att

enu

atio

n L

eng

th [

μm

]

Wavelength [nm]

Mie Scattering

Water Absorption

Combined (Mouse

Cortex Model)


Part IIIntro.

Longer wavelength excitation affects not only the attenuation length, but also

can enable the possibility of 3-photon excitation fluorescence: win, win

800 1000 1200 1400 1600 18000

250

500

750

1000

1250

1500

1750

Att

enu

atio

n L

eng

th [

μm

]

Wavelength [nm]

Mie Scattering

Water Absorption

Combined (Mouse

Cortex Model)

Increasing the Excitation Wavelength

𝑙𝑒 800 nm = 150 𝜇m

𝑙𝑒 1060 nm = 250 𝜇m

𝑙𝑒 1300 nm = 350 𝜇m

Fundamental Imaging Depth Limits

for 2PM (5𝑙𝑒) / 3PM (8𝑙𝑒)

• 750 / 1200 𝜇m

• 1250 / 2000 𝜇m

• 1750 / 2800 𝜇m

N.G. Horton et al., Nat. Photonics 7, (2013)2PM: 2-photon microscopy

3PM: 3-photon microscopy

No “Simple” ultrafast sources

at 1300 nm!!

Cr:forsterite lasers (reliability) and Ti:sapphire

pumped optical parametric oscillators ($$$)


Part IIIntro.

Generating pulses at 1250 nm in a photonic crystal fiber for 3-photon excitation

fluorescence microscopy.

`

ANDi

`

NPA

`

MC

SC






PCF: photonic crystal fiber

`

FFPSNonlinear 1250 nm pulse

generation in Dual Zero-

Dispersion Wavelength

Photonic Crystal Fiber

(PCF)PCF

Goal: • >1 nJ pulses at ~1300 nm

• minimum pulse duration (as

close to 28 fs as possible)

D. Kobat et al., J. Biomed. Opt., 16 (2011)

Part IIIntro.

Nonlinear Frequency Conversion from 1060 nm out to the 1300 nm Biological Imaging

Window

Nonlinear Frequency Conversion from 1060 nm out to the 1300 nm via Photonic Crystal

Fiber Generating pulses at 1250 nm in a photonic crystal fiber with two, closely

spaced zero-dispersion wavelengths (NL-1050-ZERO2)

850 950 1050 1150 1250-50

-40

-30

-20

-10

0

10

Wavelength [nm]

Dis

per

sion

Co

effi

cien

t

[ps/

nm

-km

]

Bulk FSLMA-PM-5

NL-1050-NEG1NL-1050-ZERO2

800 1000 1200 14000

1

Inte

nsi

ty 30 fs, 0.5 nJ

Wavelength [nm]

Fib

er L

ength

[m

m]

800 1000 1200 14000

5

10

15

20

25

30

Part IIIntro.

Numerical Model

Constructing a fiber cocktail composed of telecom and photonic crystal fiber

(PCF) with 2 zero-dispersion wavelengths (NL-1050-Zero2)

Part IINonlinearFiber Construction

Nonlinear Fiber Cocktails for Broadband Pulse Coupling with Minimal Instability

HI-1060

8 mm

PCF-Zero-2

30 mm

Optical

Fiber:

Off-Axis

Parabolic

Collimator

Free-Space

Aspheric Lens

Angle-Polished

ConnectorsLaser In• 0.67 dB Splice Loss

• 59% Transmission

• Fiber-Fiber splice

hermetically Seals PCF

PCF: photonic crystal fiber

1250 nm Pulse Characteristics after Nonlinear Frequency Conversion from 1060 nm

1250 nm generation at low powers: 0.6 nJ, 37 mW @ 61 MHz

Time [fs]

Wav

elen

gth

[nm

]

Mea

sure

d

Rec

on

stru

cted

-100 0 100

580

600

620

640

Efficiency:• 5% Depolarization

• 35% Conversion

efficiency including

fiber coupling (!)

Durations:• TL: 23 fs FWHM

• TL: 28 fs Square

• Reconstructed: 44 fs

Square

• 64% compressed

S.R. Domingue et al., Opt. Express 22, (2014)

TL: transform-limited duration

FROG: frequency resolved optical gating

Part II1250 nmPulseGeneration

Wavelength [nm]

Sp

ectr

al P

has

e [r

ad]

1150 1250 1350

-10

12

3

Pow

er S

pec

trum

[a.

u.]

-100 0 1000

0.2

0.4

0.6

0.8

1

Time [fs]

Inte

nsi

ty [

a.u

.]TL

Recon.

𝜏𝑠𝑞𝑢𝑎𝑟𝑒 =𝐸𝑛𝑒𝑟𝑔𝑦

𝑃𝑒𝑎𝑘 𝑃𝑜𝑤𝑒𝑟

Phantom-FROG

1250 nm generation at higher powers: 2 nJ, 122 mW @ 61 MHz

Efficiency:• 10% Depolarization

• Still 35% Conversion

efficiency

• Record pulse energy

at 1250 nm via fiber

nonlinear frequency

conversion

Durations:• TL: 21 fs FWHM

• TL: 29 fs Square

• FROG: 49 fs Square

• 59% compression

Time [fs]

Wav

elen

gth

[nm

]

Mea

sure

d

Rec

on

stru

cted

-100 0 100

600

620

640

660



1250 nm Pulse Characteristics after Nonlinear Frequency Conversion from 1060 nm

TL: transform-limited duration

FROG: frequency resolved optical gating

Wavelength [nm]

Spec

tral

Phas

e [r

ad]

1150 1250 1350

-10

12

3

Pow

er S

pec

trum

[a.

u.]

-100 0 1000

0.2

0.4

0.6

0.8

1

Time [fs]

Inte

nsi

ty [

a.u

.]

TL

Recon.

Phantom-FROG

At 2 nJ (200 mW coupled) there is a problematic instability. We suspect back reflections

from the fiber exit face feeding back into the fiber amplifier

1250 nm pulses have

nearly binary changes of

state.• Small changes in spectral

phase

• Larger changes in power

spectrum

• Huge change in intensity

profile

Output of Photonic

Crystal Fiber



Average Power Limitations in Nonlinear Frequency Conversion to 1250 nm Pulses

-1

0

1

2

3

4

5

Wavelength [nm]

Spec

tral

Phas

e [r

ad]

1150 1250 1350

-1

0

1

2

3

4

5

Pow

er S

pec

trum

[a.

u.]

-100 0 1000

0.2

0.4

0.6

0.8

1

Time [fs]

Inte

nsi

ty [

a.u

.]

Three-Photon Excitation Fluorescence Microscopy in the 1250 nm Biological Imaging Window

Preliminary results indicating feasibility and needs for future system

`

ANDi

`

NPA

`

MC

SC






PCF: photonics crystal fiber

`

FFPS

Stage-Scanning 3-Photon

Excitation Fluorescence

Microscopy (0.5 NA)

PCF-100 0 100

0

0.2

0.4

0.6

0.8

1

Time [fs]

Inte

nsi

ty [

a.u

.] 0.6 nJ

44 fs

xY

Part II1250 nmMicroscopy


100 𝝁m

Three-Photon Excitation Fluorescence Microscopy in the Second Biological Imaging

Window

Preliminary results indicating feasibility and needs for future system

GFP labeled mouse pancreas

Fluorescein dyed lens tissue


30 𝝁m

apart

Part II1250 nmMicroscopy

Goals and Future Work Generating 1250 nm pulses

100 𝝁m

Fluorescein dyed lens tissue

Future Work:• Reduce Parasitic Back-Reflections from

Photonic Crystal Fiber systems• Increase 1250 nm pulse energy

• Improve Spatial Mode (Degrading exit fiber

face => reduces spatial mode quality)

Part IIFinale

Goal• >1.5 nJ incident on

surface

HI-1060

1-2 mm

PCF-Zero-2

30 mm

Sealed Chamber WindowsFerrules /

Potted Fiber

Seeding Dual-Zero Dispersion Photonic Crystal Fiber with 1060 nm pulses to directly generate

1250 nm pulses for Nonlinear Microscopy

• Limited to < 3nJ (~200 mW) by

Polarization Instability in Fiber

Future Work Generating ~1300 nm pulses for Nonlinear Microscopy

• Photonic Crystal Fiber with single

Zero-Dispersion Wavelength at < 1060

nm

• Soliton Self-Frequency Shifting • 0.3 nJ, 50 fs seed pulse at 1340 nm

• Amplify in Nd-Doped ZBLAN fibers• >5 nJ

• <100 fs pulse

Part IIFinale

`

ANDi

`

NPA

`

MC




SSFS: soliton self-frequency shifting

SS

FS

Pump

Module #1

4 copies

2 copies

+ GDD

Chirped-Pulse

Amplifier

Divided-

Pulse

Amplifier

- GDD

8 copies>5 nJ 1340 nm

Amplified pulse

output

1050 nm 795 nm

LD’s

PBS

DM1

DM2

Nd-ZBLAN #1

Pump

Module #3

FR+M

Nd-ZBLAN #2Pump

Module #2

Pump

Module #4

Move to Nd-doped Fiber Amplifier for surplus pulse energy in the 1300

nm biological imaging window

Chapter 9

Chapter 11

Part III: Hyperspectral Imaging

Multiplexing spectral measurements in time using unique frequency signatures

`

ANDi

`

NPA

`

MC

SC






`

FFPS

• ~25 fs

• >350 kW

• 10 nJ @ 60 MHz

• 600 mW

`

Laser Scanning

Multi-photon

Microscopy

`Nonlinear Laser

Machining

`

3-Photon

Excitation

Fluorescence

Microscopy

`

Hyperspectral

Imaging via

Excitation Labeled

Fluorescence

`

Nonlinear 1250

nm pulse

generation`

Second

Harmonic

Generation

Part IIIIntro.

Hyperspectral Imaging and Spectral Multiplexing more Generally

The desire on both fronts is to eliminate the requirement of a

1- or 2-dimensional photo-detector array

Futia, G. et al, Opt. Express 19, (2011)

Diebold, E. D. et al., Nat. Photonics 7, (2013)

Spatial Frequency Modulated

Imaging

Encodes Spatial Information

into the time-domain

Decouples imaging speed from

camera frame rate:• Single-Element Photodetector

bandwidths virtually unlimited

• Demonstrated 4 kHz confocal

fluorescence frame rates*

To add a hyperspectral modality,

we desire something other than

spatially disperse and capture with

an array detector!

Part IIIIntro.

The desire on both fronts is to eliminate the requirement of a

1- or 2-dimensional photo-detector array

Weber, J. R. et al., J. Biomed. Opt. 16, (2011)

Hyperspectral information

enables:

Encodes Spatial Information

into the time-domain

• Scattering, absorption, and

fluorescence (tissue optical

properties => disease indicators)

• Imagination limited

applications: • electronic to vibrational

interactions

• photo-thermal imaging

• excitation labeled fluorescence

Part IIIIntro.

Hyperspectral Imaging and Spectral Multiplexing more Generally

Spatial Frequency Modulated

Imaging

Light Labeling for Hyperspectral Imaging and General Spectroscopy: a New Method

Down shifting the angular carrier frequencies of an optical bandwidth into a directly

measureable frequency range: 500 THz @ 2000 THz => 100’s Hz @ 100-10 kHz

Related to Fourier Transform Spectroscopy,

except we encode a wavelength dependent

intensity modulation onto power spectrum

Moves the “Spectrometer” from

the back-end of the experiment

to the front-end

Transfers wavelength/spectroscopic

information into the time-domain

Fluorescent Intensity

Fluorescent Intensity and

Fluorophore Identification

Alexa

Fluor 514

Alexa

Fluor 546

Part IIIIntro.

S.R. Domingue et al., Optica, Publication Pending

Modulating the spectral line-focus within a folded 4-F Martinez with a

frequency modulated reticle

Light Labeling via Spectral Intensity Modulation

The color to space mapping:

𝑓 Ω = 𝑟0 + 𝛼Ω

Diffraction

Grating

Side ViewF

F

Motor

Mirror

Reticle Side view of reticle and

spectral line focus

M(r,t) = 1

2+

1

2𝑠𝑖𝑔𝑛(cos 2𝜋Δ𝑘 𝑟𝜈𝑅𝑡 )

Δ𝑘 is in cycles / unit radius:

Δ𝑘 = 5 𝑚𝑚−1 → 𝑀(𝑟 = 1 𝑚𝑚) has 5

cycles (or periods) per revolution of the

reticle and

𝑥(𝜔) = 𝛼Ω

𝑥(𝜔0) = 0

The lateral displacement of

wavelets after the lens:

𝑥

Ω = 𝜔 − 𝜔0.

sign() enforces binary modulations

𝜈𝑟: rotation rate𝛼 ≈

2𝜋𝑐𝑁𝐹

𝜔02 cos 𝜃

Part IIILightLabeling

𝜈𝑅

Modulating the spectral line-focus within a folded 4-F Martinez with a

frequency modulated reticle

The Physical Means of Encoding the Spectral

Modulation for Light Labeling

𝜈𝑅

The color to space mapping:

𝑓 Ω = 𝑟0 + 𝛼Ω

Combined with the spatial mask fcn:

M r, t =1

2+1

2𝑠𝑖𝑔𝑛(cos 2𝜋Δ𝑘 𝑟𝜈𝑅𝑡 )

Affects a Power Spectral Modulation:

M r, t → M(Ω, 𝑡)

𝐼 Ω, 𝑡 = M Ω, 𝑡 𝐴 Ω

𝐴(Ω): power spectral envelope

Ω = 𝜔 − 𝜔0.

𝜈𝑟: rotation rate

sign() enforces binary modulations

Diffraction

Grating

F

F

Motor

Mirror

Reticle

𝑥(𝜔) = 𝛼Ω

𝑥(𝜔0) = 0

The lateral displacement of

wavelets after the lens:

𝑥

Ω = 𝜔 − 𝜔0.


-90 -60 -30 0 30 60 90

0

0.25

0.5

0.75

Transmitted Power Spectrum as a function of Reticle Angle

The Temporal Intensity imparted by the Frequency Modulated Reticle

Photodetector

Wavelength-Independent, Single-Element Detection:

s 𝑡 = ∫ 𝐼 Ω, 𝑡 𝑑ΩWavelength

Pow

er S

pec

tru

m

𝜃 = 0∘

Excitation

Spectrum

Transmitted

Spectrum,

𝐼(Ω, 𝑡)

𝜃 = 3.5∘𝜃 = 7∘𝜃 = 10.5∘𝜃 = 17.5∘𝜃 = 70∘

Reticle Angle [deg] / 2𝜋 𝜈𝑟𝑡

s(t)


Isolating the first sideband in the Fourier transform of 𝑠(𝑡), 𝑆(𝜈) = 𝐹𝐹𝑇{𝑠(𝑡)}, returns the excitation power spectrum

𝐹𝐹𝑇{𝑠(𝑡)}

The electric field carrier frequencies (𝜔) of the optical

bandwidth down shifted to a frequency range Hz-MHz

LiL

aP

ow

er

Spec

trum

, 𝑆(𝜈)

Modulation Frequency →← Wavelength

The Temporal Intensity imparted by the Frequency Modulated Reticle

LiL

a S

ignal

, 𝑠(𝑡)

Reticle Angle

/ 2𝜋 𝜈𝑟𝑡


Measuring Power Spectra with the Light Labeling (LiLa) system

Spectral Resolution of Single-Element Detector Spectroscopy with Light Labeling

Wavelength [nm]

Po

wer

Sp

ectr

a [a

.u.]

510 530 550

LiLa

Ocean Optics

with:

Spectral resolution depends on:

• reticle Δ𝑘• monochromatic wavelet focal spots sizes

incident on the reticle, 𝑤𝐹𝑊𝐻𝑀

1

Δ𝑘𝑤𝐹𝑊𝐻𝑀

For the case 𝑤𝐹𝑊𝐻𝑀 ≪1

Δ𝑘, the Spectral Resolution:

𝛼𝛿Ω =1

Δ𝑘→ 𝛿𝜆 =

cos 𝜃

Δ𝑘 𝑁 𝐹(= 0.8 nm)

Numerical Values for our System

𝑤𝐹𝑊𝐻𝑀 = 20 𝜇m and 1

Δ𝑘= 200 𝜇m

sin 𝜃 = 𝑁𝜆0 − sin(17.5∘).𝑁=1200 L/mm: grating ruling density

𝐹=200 mm : focal length in Martinez S.R. Domingue et al., Optica, Publication Pending


90 spectral points (limited by

available bandwidth)

Time / Reticle AngleL

iLa

Sig

nal

, 𝑠(𝑡)

FFT{𝑠(𝑡)}

Modulation

Frequency

LiL

aP

ow

er

Spec

trum

, 𝑆(𝜈)

𝜈′

Calibrated

Spectrometer

Razor Blade

Wav

elen

gth

Modula

tion

Fre

quen

cy

𝜈′

Razor Position

𝜆′

𝑥′

Co-Locating EdgesCaptured by

spectrometer

Captured by Light Labeling

With RazorNo Razor

Wavelength

Pow

er

Spec

trum

, C

ounts

𝜆′

𝜆[𝑛𝑚] = −0.14𝜈[𝐻𝑧] + 620

Measured mapping between 𝜈 and 𝜆

Locating known edges in power spectrum: for example, a razor blade in

spectral line focus

Calibrating the Light Labeling system

Wav

elen

gth

[nm

]

Modulation Frequency [Hz]500 650 800

510

530

550Data


Background-Free Absorption Imaging via Light Labeling and Excitation Labeled

FluorescenceTransferring the Light Labeling modulations from the excitation power

spectrum to a fluorophore via absorption

Wavelength

No

rmal

ized

Sp

ectr

a Excitation

Fluorophore A

Fluorophore B

Absorbed

spectrum

(filled)

Fluorophore A

Fluorophore B

Wavelength

Em

issi

on

Sp

ectr

a

The broadband fluorescent emission retains

the temporal label of absorbed wavelengths

LiLa Excitation

Pulse

TimeE

mis

sio

n I

nte

nsi

ty

Higher

Frequencies

Time-

Domain

Wavelength-Domain

507090 Hz

Modulation

Frequency


Part IIIExcitationLabeledFluorescence

Background-Free Absorption Imaging via Light Labeling: Excitation Labeled Fluorescence

The fluorescent emission intensity contains the temporal Light Labeling

modulations, from which the absorbed power spectrum is recovered

Wavelength

Em

issi

on

Sp

ectr

a

Time

Em

issi

on

In

tensi

ty

Excitation

Fluorophore A

Fluorophore B

FFT{𝑠(𝑡)}

Exci

tati

on

Time

Wavelength →L

iLa

Rec

ov

ered

Ab

sorb

ed S

pec

tra

← Modulation Frequency

Absorption Spectra

Absorbed Spectra

Part IIIExcitationLabeledFluorescence

For weakly separated absorbed spectra the un-absorbed spectra can

magnify the contrast for algorithmic species identification.

FrequencyU

n-a

bso

rbed

Spec

trum

Part IIIHI-ELFMicroscope

𝑆un,546 𝜈 .

𝑆un,514 𝜈 .

𝑆un 𝑥𝑖 , 𝑦𝑗 , 𝜈 .

Absorbed Spectra Characteristics:

Alexa Fluor 514

• Δ𝜆 = 16 nm FWHM

• Δ𝜆0 = 524 nm

Alexa Fluor 546

• Δ𝜆 = 22 nm FWHM

• Δ𝜆0 = 527 nm

500 510 520 530 540 5500

0.2

0.4

0.6

0.8

1

Wavelength [nm]

Ab

sorp

tio

n S

pec

tra

[a.u

.]

0

0.2

0.4

0.6

0.8

1𝑆excitation𝑆546𝑆514.

𝑆546.

𝑆514.𝑆(𝑥𝑖 , 𝑦𝑗)

Using Excitation Labeled Fluorescence for Fluorescent Species Identification

𝑆𝑢𝑛−𝐴𝑏𝑠 𝜆 = 𝑆𝐸𝑥𝑐 𝜆 − 𝑆𝐴𝑏𝑠𝑜𝑟𝑏𝑒𝑑(𝜆)

y

x

t

𝑠(𝑥, 𝑦; 𝑡)

The frame rate of a high speed camera and Light Labeling converts the time-domain

trace from each camera pixel into a spectral measurement

Hyperspectral Imaging via Excitation Labeled Fluorescence (HI-ELF)

Sequential HI-

ELF Micrographs

of Fluorescent

Intensity

reference spectrum

Camera

Dichroic

Mirror

Long Pass

Filter

HI-ELF Microscope


10x /

0.2 NA

200 250 300 350

552 535 518 504

Frequency [Hz]

Spec

trum

[a.

u.]

Wavelength [nm]

FFT{s(t)}𝑆𝐸𝑥𝑐 𝜆 −

𝑆′(𝜆)

0 0.25 0.5-6

-4

-2

0

2

4

Time [s]

Sig

nal

, s(

t) [

V]

200 250 300 350-0.5

0

0.5

1

1.5

2552 535 518 504

Frequency [Hz]U

n-A

bso

rbed

Spec

trum

[a.

u.]

Wavelength [nm]

Processing the Light Labeled signal at each pixel

y

x

t


The frame rate of a high speed camera and Light Labeling converts the time-domain

trace from each camera pixel into a spectral measurement


Sequential HI-

ELF Micrographs

of Fluorescent

Intensity

Species weighting at each pixel by least mean-squared-error search

𝑆 𝑥𝑖 , 𝑦𝑗 , 𝜈 = 𝑎546 𝑥𝑖 , 𝑦𝑗 𝑆un,546 𝜈 + 𝑎514 𝑥𝑖 , 𝑦𝑗 𝑆un,514(𝜈)

Species weighted micrographs:

𝐼514,546 𝑥𝑖 , 𝑦𝑗 = ∫ 𝑆 𝑥𝑖 , 𝑦𝑗 , 𝜈𝑎514,546(𝑥𝑖,𝑦𝑗)

𝑎514 𝑥𝑖,𝑦𝑗 +𝑎546(𝑥𝑖,𝑦𝑗)𝑑𝜈

reference spectrum

Camera

Dichroic

Mirror

Long Pass

Filter

HI-ELF Microscope

Frequency

Un-a

bso

rbed

Sp

ectr

um

𝑎546 𝑥𝑖 , 𝑦𝑗 𝑆un,546 𝜈 .

𝑎514 𝑥𝑖 , 𝑦𝑗 𝑆un,514 𝜈 .

𝑆 𝑥𝑖 , 𝑦𝑗 , 𝜈 .

These fits are distinguishing between Absorbed

Spectra with centroids separated by 3 nm


10x /

0.2 NA

y

x

t


Micrographs of differentiated fluorescent species based on absorbed spectra, recovered

from the temporal dynamics of the broadband fluorescent emission intensity


Sequential HI-

ELF Micrographs

of Fluorescent

Intensity

Images of total emission intensity (Left) and emission intensity weighted

by species coefficients, 𝐼514,546 𝑥𝑖 , 𝑦𝑗 , (Right)

Alexa Fluor 514 and 546 in blue and red, respectively

Camera

Dichroic

Mirror

Long Pass

Filter

HI-ELF Microscope

reference spectrum



10x /

0.2 NA

Future Work for Hyperspectral Imaging via Light Labeling

Part IIIFinale

Future Work:• A Generalized Theory of Light

Labelingy

x

t


Part IIIFinale


Labeling

• Add Spatial Frequency Modulated

Imaging to current green Light

Labeling system

Single-

Element

Detector Cylindrical

Lens

Dichroic

Mirror


Part IIIFinale


Labeling

• Add Spatial Frequency Modulated

Imaging to current green Light

Labeling system

• Calibrate a Light Labeling

spectrometer at 2 𝜇m to capture

Second-Harmonic Generation

Frequency Resolved Optical

Gating (SHG-FROG) traces

Single-

Element

Detector

4 𝜇m

SHG-

FROG

Special Thanks

The Bartels Ultrafast Lab

Philip Schlup

Omid Masihzadeh

Jesse Wilson

Jeff Field

David Winters

David Kupka

David Smith

Keith Wernsing

Patrick Stockton

Committee Members

Amber Krummel

Diego Krapf

Mario Marconi

Funding Sources

Department of Energy

Office of Naval Research

National Institute of Health

The Keck Foundation

Colorado State University

Special Thanks

My ANDis

Blandi (CSU)

Negato (CSU)

Blazer (CSU)

Kandi (CSU)

Boomer/Athena (CSU)

Mandi (CU-Denver)

Jandi (CSM)

Nandi (NREL)

Extra-Special Thanks

My Adviser

Randy Bartels

My Fiancée

Stephanie Krueger

Q.E.D.

Nonlinear Pulse Compression a la Warhol

Development and Implementation of Near- Infrared Ultrafast ... Final... · Infrared Ultrafast Laser...

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Transcript of Development and Implementation of Near- Infrared Ultrafast ... Final... · Infrared Ultrafast Laser...