Ultrafast Components - TSUKASA TECtsukasa-tec.co.jp/product/optics/documents/CVI... · CVI has been providing researchers with optics optimized for femtosecond operation for over

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sIntroUltrafast Components

Ultrafast Discussion . . . . . . . . . . . . 264

Broadband Mirrors. . . . . . . . . . . . . 266

Ti:Sapphire Broadband Mirrors . . . 270

Argon-Ion 488-515nm Mirrors . . . . 271

Nd:YAG 532nm Mirrors . . . . . . . . . 272

Short Wave Pass

Dichroic Beamsplitters . . . . . . . . 273

Broadband Low GVD Mirrors. . . . . 274

Negative GVD Mirrors . . . . . . . . . . 275

Low Dispersion Polarizers. . . . . . . . 276

Isosceles Brewster Prisms . . . . . . . . 277

Femtosecond Beamsplitters . . . . . . 278

λ µ

Ωωω

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264 Americas (505) 296-9541 | Europe +44 (0) 1624 647000 | Asia +82 (0) 32 673-6114 | Order now at www.cvilaser.com

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Ultrafast Components

1. Introduction

CVI has been providing researchers

with optics optimized for femtosecond

operation for over a decade. Now CVI

offers dispersion control mirrors, which

include the LGVD and the TNM2, to

reduce pulse broadening inside or outside

the cavity.

2. Some Basics

The distinguishing aspect of femtosecond

laser optics design is the need to control

the phase characteristic of the optical

system over the requisite wide pulse

bandwidth. CVI has made an intensive

theoretical study of these effects. Certain

coating designs have been modified with

control of the phase characteristics in

mind. New proprietary designs have

been created with desirable characteristics

for femtosecond researchers. All optics

in this section have been tested by

researchers in the field and we are

constantly fielding new requests.

Assume that the power, reflectivity and

polarization characteristics of a laser

mirror are acceptable over the bandwidth

of a femtosecond pulse. This means

that over the entire pulse bandwidth,

a cavity mirror may have a reflectivity

greater than 99.8%. A 50% beamsplitter

may have a fairly constant reflection. A

polarizer may maintain its rejection of

one polarization with an acceptable

transmission of the other. It is not

enough, however, to simply preserve

the power spectrum S(ω)=|E(ω)|2 when

dealing with femtosecond pulses. The

phase relationship among the Fourier

components of the pulse must also be

preserved in order that the pulse not be

broadened or distorted. What constraint

on the performance of a mirror or

transmissive optic does this imply?

Consider a general initial pulse shape Eo(t).

As a function of its Fourier components, it

may be expressed as:

Suppose this pulse reflects off of a mirror.

For this example, we assume the mirror is

“ideal”, and use for the Fourier transform

of its complex amplitude reflectance:

In this “ideal” mirror response case, r is

a real constant equal to the amplitude

reflectivity that is assumed constant over

the pulse bandwidth. All phase effects

have been assumed to be describable

by a single phase shift Φ(ω) that is

linearly proportional to frequency with

proportionality constant td. The reflected

pulse is then:

Thus, provided the phase shift is linear in

frequency over the pulse bandwidth, the

reflected pulse is scaled by the amplitude

reflectance r, and delayed in time by the

constant group delay td. It is, otherwise,

an undistorted replica of the original pulse.

Examined over a large enough bandwidth,

no optical system will exhibit the constant

group delay over frequency needed for

perfect fidelity. In general, the phase shift

near some center frequency ωo may be

expanded in a Taylor series for frequencies

near ωo:

These derivatives are, respectively, the

group delay Φ’(ωo), the group velocity

dispersion Φ’’(ωo), and the “cubic term”

Φ’’’(ωo) evaluated at a center frequency

ωo. This expansion is heuristically

useful, in an exactly soluble model, for

the propagation of a transform limited

Gaussian pulse. Note, however, that for

extremely short pulses the expansion

above may be insufficient. A full

numerical calculation may have to be

performed using the actual phase shift

function Φ(ω). CVI will be happy to assist

those interested in the modeling of real

optical elements.

To illustrate pulse distortion due to

the dependence of the group delay on

frequency, consider what happens when

an unchirped, transform-limited Gaussian

pulse passes through a medium, or is

incident on a mirror whose dominating

contribution to phase distortion is non-

zero group velocity dispersion. The field

envelope of the pulse is assumed to be of

the form:

r(ω) = re+iΦ(ω) = re+iωtd

Φ(ω) = Φ(ωo) + Φ'(ωo) · (ω - ωo) + Φ’’(ωo) · (ω - ωo)2 / 2! + Φ'''(ωo) • (ω - ωo)3 / 3!+...

⌠⌡

Eo(t) = E (ω)-iωt dω

Er (t) = r E (ω) -iω (t - td) dω

= r Ε (t - td)

⌠⌡

E(t) = exp [ - (2 ln2 t2 / τo2) ]

where τo is the initial pulse duration

(FWHM of the pulse intensity). Let the

pulse enter a medium or reflect off of a

mirror with non-zero Φ’’(ω), measured in

fsec2/ radians. (For a continuous medium-

like glass, Φ’’(ω) = β’’(ω) · z where β’’(ω)

is the group velocity dispersion (GVD)

per cm of material, and z is the physical

path length in cm travelled through the

material.) The Gaussian pulse will be both

chirped and temporally broadened by its

encounter with group velocity dispersion.

The power envelope will remain Gaussian;

the result for the broadened FWHM is:

τ1 = τo [ 1 + (4 ln2 Φ’’ (ω) / τo2 )2 ]1/2

Technical Notes



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which are a hybrid of the two. Shown on

the next page are graphs of the reflectivity,

group velocity dispersion parameter and

cubic dispersion parameter for TLM1 and

TLM2 high reflectors. In these examples,

the mirrors are centered at 800nm and

designed for use at normal incidence

and at 45°. Note that at the design

wavelength: (1) GVD is zero;

(2) the cubic term is a minimized;

and (3) at 45° incidence, the GVD

of the P polarization is very sensitive

to wavelength, while the GVD for S

polarization is nearly zero over a broad

wavelength range. Thus one should avoid

using mirrors at 45° incidence with the

P polarization. On the other hand, 45°S

incidence provides very broad bandwidth

and minimizes pulse distortion problems

and should be used when possible.

Ti:Sapphire and other femtosecond laser

systems need prismless compensation of

the built-in positive chirp encountered

in the laser optical circuit. This becomes

mandatory in industrial and biomedical

applications where the laser must provide

a compact, stable, and reliable solution.

TNM2 Series Negative Group Velocity

Dispersion Mirrors meets these needs

with off-the-shelf. TNM2 mirrors can be

employed both intra and extracavity to

satisfy chirp control requirements.

In experiments, 200mW, 80 fsec pulses

centered at 785nm were achieved in a

simple, prismless, Ti:Sapphire oscillator.

The configuration is shown in the diagram.


This result, valid only for initially

unchirped, transform limited Gaussian

pulses, is nevertheless an excellent model

to study the effects of dispersion on

pulse propagation. The following graphs

present theoretical broadening from

dispersion for initial pulse width from 10

to 100 femtoseconds.

Output Pulse Width vs. GVD

3. GVD & Cubic Dispersion for

Various Optical Materials

The charts of GVD and cubic dispersion

for some common used glasses follow.

Some of the glasses can be used in the

UV region. They should be useful in

estimating material dispersion and pulse

distortion effects. Please check these

calculations independently before using

them in a final design.

GVD and Cubic Dispersion for

Various Materials

Technical Notes

continued

4. Dispersive Properties of Mirrors

CVI uses three basic designs; TLM1

mirrors for large energy fluence >100mJ/

cm2, TLM2 mirrors for CW oscillators and

low fluence pulses, and TLMB mirrors




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The main emphasis is on linear phase

characteristics. See Chapter 9 of Lasers,

A. E. Siegman (University Science Books,

Mill Valley, California, 1986), for a good

discussion of linear pulse propagation.

In chirped pulse regenerative

amplification, the pulse may have to pass

through one or two polarizers twice per

round trip. There can be 10 to 20 round

trips before the gain is saturated and the

pulse is ejected. At this stage the pulse

is long (100ps-1000ps) although, the

phase shift at each frequency must still be

maintained to minimize the recompressed

pulse width. The many round trips of

the pulse in the regenerative amplifier

put stringent requirements on the phase

characteristics of the coatings.

Shown are the power transmission

curves for S and P polarization and the

transmitted phase characteristics of

the P component for a TFPK optimized

at 800nm. (Users may specify any

wavelength from 250nm - 1550nm.) The

phase characteristics shown are the group

velocity dispersion (GVD) and the cubic

phase term. Not shown are the reflected

phase characteristics for S; they are similar

to the P transmission curves, also having

low nonlinearity and broad bandwidth.

Note that both sides of the optic have the

coating whose properties are described

in the figures on the following page.

Therefore, the S and P transmissions

per surface should be squared in

determining the specifications. The phase

characteristics show that in all modes of

operation, the TFPK polarizer performance

is dominated by the substrate.

There are some subtleties associated

with the TFPK. The near 72° angle has

to be set properly and optimized. Some

Photo depicts typical optical set-up of CVI Negative GVD mirrors.

5. Output Couplers and Beamsplitters

Output coupler partial reflectors and

beamsplitters behave similarly; however,

here is an additional consideration in their

analysis. The behavior of the transmitted

phase of the coating and the effect of

material dispersion within the substrate

on the transmitted beam have to be taken

into account in a detailed analysis. In

general, the coating transmitted phase

has similar properties and magnitudes of

GVD and cubic to the reflected phase.

As usual, centering is important. As a

beamsplitter, CVI recommends the 1.5mm

thick fused silica substrate PW-1006-UV.

As an output coupler substrate, we

recommend the 3.0mm thick, 30 minute

wedge fused silica substrate IF-1012-UV.

CVI has developed the TFPK Series

Broadband Low Dispersion Polarizing

Beamsplitters to satisfy requirements

for very high power, short pulse lasers.

These optics are ideal for intracavity use

in femtosecond regenerative amplifiers.

Typical optical set-up incorporating low GVD and Negative GVD mirrors in an ultrafast application.

Dispersion and Reflectivity for Mirrors

TLM1-800-0 and TLM1-800-45

Φ

ω

Φ

ω

Dispersion and Reflectivity for Mirrors

TLM2-800-0 and TLM2-800-45

Φ

ω

Φ

ω

Technical Notes




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at 800nm. The linear pulse propagation

properties of these beamsplitters are

dominated by the substrate material

dispersion. As with virtually all dielectric

coated optics, the S polarized version

is broader than P polarized. CVI can

produce FABS in other than 50:50 with

excellent phase characteristics.

6. Anti-Reflection Coatings

All CVI antireflection coating designs

work well in femtosecond operation as

the forward-going phasor is the dominant

contribution to the phase shift; the AR

coating is very thin and simply “fixes” the

small Fresnel reflection of the substrate.

7. Prisms

Very high quality Isosceles Brewster’s angle

prisms for intra and extracavity use may be

found on page 277. The design of these

prisms satisfies the condition of minimum

loss due to entrance and exit at Brewster’s

angle. To calculate GVD at Brewsters

angle, use the following:

n = refractive index of prisms

(assuming the same material)

l = tip to tip distance (AB)

L = total avg. glass path

ψ = spectral phase of the electric field

where ωl λl = 2πc: assumes Brewster

prism at minimum deviation.

For more on the Ultrafast phenomena,

see J.C. Diels and W. Rudolph, Ultrashort

Laser Pulse Phenomena, Academic Press,

1996, (2nd edition planned for 2006).

Properties for one coated side of a TFPK polarizing beamsplitter optimized for 800nm. Both sides are coated for these properties.

thought has to be given to mechanical

clearances of the laser beam at such a

steep incidence angle. The reflectivity for

S is limited to 75%. Variant designs can

increase this at a slight loss in bandwidth,

increase in incidence angle, and increase

in insertion loss for the transmitted P

component.

FABS Autocorrelator beamsplitters

are broadband, 50% all-dielectric

beamsplitters. They are useful in many

types of pump-probe experiments and

in the construction of anti-resonant ring

configurations. They are essentially

lossless and extremely durable. Both are

advantages over partially reflecting metal

coatings.

Shown here are power transmission

curves for the S and P polarized versions

with the corresponding reflected phase

characteristics for beamsplitters optimized

The curves above represent the performance of two distinct beamsplitters. Beamsplitters for both S and P polarizations must be specified separately.

FABS-800-45P

FABS-800-45S

Technical Notes

ψ ≈

ωωω

λπ

λ

λ

λ

λ

(— + —)/ //

—




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Broadband Mirrors TLM2

TLM2

Coated surface figure λ/10 over 85% of diameter

Low dispersion CW oscillators Contact a CVI applications

engineer for OEM mirror mounts and system integrations capabilities

Mirror mounts are available l 357

The TLM2 mirrors are specially designed

to achieve high reflectivity and low

dispersion for CW oscillators and low

fluence pulses. These mirrors can be

coated for any angle of incidence from

0° to 60° and any center wavelength

between 450nm and 2100nm. For 45°

tuning mirror applications involving very

short pulses or very broad bandwidths,

CVI recommends using S-polarization if

possible. This minimizes pulse distortion

and maximizes average reflectivity. Check

that the bandwidth is realistic by using the

table on the bottom of the next page, then

specify the exact center wavelength and all

other parameters in the ordering block on

the next page. See information graph for

GVD of various materials l 265.

For higher damage threshold or UV

applications, see TLM1 l 154.

For Ultrafast Applications

Shown on the left are graphs of the

reflectivity, group velocity dispersion

parameter and cubic dispersion parameter

for TLM2. These examples, the mirrors

are centered at 800nm and designed

for use at normal incidence and at 45°.

Note that at the design wavelength:

(1) GVD is zero; (2) the cubic term is a

minimized; and (3) at 45° incidence,

the GVD of the P polarization is very

sensitive to wavelength, while the GVD for

S polarization is nearly zero over a broad

wavelength range. Thus one should avoid

using mirrors at 45° incidence with the

P polarization. On the other hand, 45°S

incidence provides very broad bandwidth

and minimizes pulse distortion problems

and should be used when possible.

Narrowband TLM1 mirrors can be found

on l 154.

Φ

ω

Cubic dispersion vs. Wavelength of TLM2-800 Broadband Laser Mirror showing 0° and 45° angle of incidence designs.

Φ

ω

Group velocity dispersion vs. Wavelength of TLM2-800 Broadband Laser Mirror showing 0° and 45° angle of incidence designs.

Reflectivity vs. Wavelength of TLM2-800 Broadband Laser Mirror showing 0° and 45° angle of incidence designs.

Substrate Material BK7 glass

S1 Surface Figure λ/10 at 633nm before coating

S1 Surface Quality 10-5 CVI Laser Quality defined on page 430

S2 Surface Quality Commercial polish

Diameter Tolerance + 0.00mm, − 0.25mm

Thickness Tolerance ± 0.25mm

Wedge ≤ 5 minutes

Chamfer 0.35mm at 45° typical

Concentricity ≤ 0.05mm

Radius Tolerance ± 0.5%

Coating Technology Electron beam multilayer dielectric

Adhesion and Durability Per MIL-C-675C. Insoluble in lab solvents.

Clear Aperture Exceeds central 85% of diameter

Bandwidth Tolerance + 0%, − 10% typical

λc Tolerance ± 3%

Damage Threshold 100mJ/cm2, 8nsec pulse at 1064nm

Coated Surface Figure λ/10 at 633nm on select substrates




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sIntroTLM2 Broadband Mirrors

TLM2

Product Code

TLM2

Center Wavelength (nm)

450 650 850 1030 1200 1600

500 700 900 1050 1300 1800

550 750 950 1080 1400 2100

600 800 1000 1100 1500

Angle of Incidence degrees with Polarization

0 45S 45P 45UNP

Size Code Diameter Thickness

0537 0.500" 0.375" 1025 1.000" 0.250" 1940 50.0mm 10.0mm

0643 15.0mm 11.0mm 1032 1.000" 8.0mm 2037 2.000" 0.375"

0737 0.750" 0.375" 1037 1.000" 0.375" 3050 3.000” 0.500”

0924 25.0mm 6.0mm 1537 1.500" 0.375" 4050 4.000” 0.500”

Radius of Curvature (m) (CC=concave, CX=convex, omit for flat mirror) l 428

0.025 0.10 0.25 0.75 1.5 4.0 7.0 10.0

0.05 0.15 0.30 1.0 2.0 5.0 8.0 15.0

0.075 0.20 0.50 1.2 3.0 6.0 9.0 20.0

How To Order 0.15CC10370650TLM2

850 161 204 76

900 167 212 77

950 171 219 77

1000 180 230 80

1100 193 248 83

1200 210 264 90

1300 221 280 91

1400 238 294 98

1500 255 315 105

Center Bandwidth (nm) Wavelength R > 99% R > 99% R > 99% (nm) 0° 45°S 45°P

450 90 113 45

500 100 125 50

550 110 138 55

600 120 150 60

650 130 163 65

700 140 175 70

750 150 188 75

800 156 197 76

Center Bandwidth (nm) Wavelength R > 99% R > 99% R > 99% (nm) 0° 45°S 45°P




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TLMBTi:Sapphire Broadband Mirror

High damage threshold Broadband dielectric design High reflectivity: 740nm - 860nm Contact CVI for other wavelengths Curved mirrors and other dimensions

are available upon request

Traditional high damage mirrors are

limited in bandwidth. Broader reflectivity

bands can be achieved by using different

coating materials, but that reduces the

damage threshold.

Through active research in different

coating methods and materials, CVI

has designed this mirror which is a

high performer in all three areas:

TLMB

How To Order 102545800TLMB

Product Code

TLMB

Wavelength (nm)

800

Angle of Incidence in degrees

0 45


0525 0.500" 0.250" 0924 25.0mm 6.0mm 2037 2.000" 0.375"

0624 15.0mm 6.0mm 1025 1.000" 0.250"

0725 0.750" 0.250" 1940 50.0mm 10.0mm

high reflectivity, broad bandwidth, and

high damage threshold. It combines the

benefits of a broadband low dispersion

mirror with those of a high damage

threshold high reflector.

These mirrors are available upon special

request for all Ti:Sapphire laser-related

center wavelengths.

A comparison of Reflectance Group Delay Dispersion vs. Wavelength of traditional broadband, traditional high LDT, and the CVI TLMB mirror.

Reflectivity vs. Wavelength of TLMB-800 Ti:Sapphire Broadband Mirror showing 0° and 45°UNP angle of incidence designs.







Wedge ≤ 5 minutes



Reflectivity > 99% at 0° or 45°

Damage Threshold 8J/cm2, 20ps, 20Hz at 800nm





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Product Code Laser Wavelength

AR1 Argon-Ion 488-515nm


0537 0.500" 0.375" 0737 0.750" 0.375" 1025 1.000" 0.250"

0643 15.0mm 11.0mm 0924 25.0mm 6.0mm 1037 1.000" 0.375"


0 45

Polarization

S P UNP


0.025 0.10 0.25 0.75 1.5 4.0 7.0 10.0

0.05 0.15 0.30 1.0 2.0 5.0 8.0 15.0

0.075 0.20 0.50 1.2 3.0 6.0 9.0 20.0

How To Order 0.50CCUNP450924AR1

Argon-Ion Pump MirrorsAR1

Reflectivity vs. Wavelength of AR1 Series 488-515nm Argon-Ion Laser Mirror at 0° incidence angles.

Laser mirrors for femtosecond operation

require a large bandwidth and linear phase

versus frequency characteristics. This is

achieved by a well centered single stack

dielectric coating of sufficient bandwidth

and minimum loss.

CVI offers sets of mirrors for all varieties

of Ti:Sapphire lasers, steering mirrors

that do not degrade pulse width at all

To minimize astigmatism in off-axis pumping, many users have requested D-Shaped mirrors. To order a D-Shaped mirror, append -D to the part number and specify the distance S as shown. Note that S is measured between the flat surface to the opposite curved edge.

wavelengths, and dichroic mirrors to

admit the pump beam into your resonator

configuration. All mirrors have extremely

durable, hard electron beam deposited

dielectric coatings with special attention

paid to the above factors. Mirrors ordered

at the same time are generally matched

to each other for no additional charge.

Consult CVI for special mirror sets.

AR1







Wedge ≤ 5 minutes







Damage Threshold 1MW/cm2, CW at 515nm typical





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Reflectivity vs. Wavelength of Y2 Series 532nm Nd:YAG Laser Mirror at 0° and 45° incidence angles.

Nd:YAG 532nm Laser Mirrors Y2

Product Code Laser Wavelength

Y2 Nd:YAG 532nm


0537 0.500" 0.375" 0737 0.750" 0.375" 1025 1.000" 0.250"

0643 15.0mm 11.0mm 0924 25.0mm 6.0mm 1037 1.000" 0.375"


0 45

Polarization

S P UNP


0.025 0.10 0.25 0.75 1.5 4.0 7.0 10.0

0.05 0.15 0.30 1.0 2.0 5.0 8.0 15.0

0.075 0.20 0.50 1.2 3.0 6.0 9.0 20.0

How To Order 0.50CCUNP00537Y2

Laser mirrors for femtosecond operation

require a large bandwidth and linear phase

versus frequency characteristics. This is

achieved by a well centered single stack

dielectric coating of sufficient bandwidth

and minimum loss.

CVI offers sets of mirrors for all varieties

of Ti:Sapphire lasers, steering mirrors

that do not degrade pulse width at all

wavelengths, and dichroic mirrors to

admit the pump beam into your resonator

configuration. All mirrors have extremely

durable, hard electron beam deposited

dielectric coatings with special attention

paid to the above factors. Mirrors ordered

at the same time are generally matched

to each other for no additional charge.

Consult CVI for special mirror sets.

To minimize astigmatism in off-axis pumping, many users have requested D-Shaped mirrors. To order a D-Shaped mirror, append -D to the part number and specify the distance S as shown. Note that S is measured between the flat surface to the opposite curved edge.

Y2







Wedge ≤ 5 minutes







Damage Threshold 20J/cm2, 20ns, 20Hz; 1MW/cm2, CW at 1064nm





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SWP

Fluorescence microscopy Optical parametric generation Customer specified reflected and

transmitted wavelengths To maximize efficiency, reflect 45° S

and transmit 45° P Mounts are available l 357

Substrate Material UV grade fused silica or BK7 glass

Surface Figure λ/10 at 633nm before coating

Surface Quality 10-5 CVI Laser Quality defined on page 430

Diameter Tolerance + 0.00mm, - 0.25mm


Wedge ≤ 5 minutes


Average Transmission > 80% in short wave pass

Reflectance R ≥ 99.5% at user specified λ (248-2100nm)



Clear Aperture Exceeds central 85% of dimension

Antireflection Coating R ≤ 0.25%, 45° P; R ≤ 1.3%, 45° S

Damage Threshold 10J/cm2, 20ns, 20Hz; 1MW/cm2, CW at 1064nm

Transmission vs. Wavelength of Short Wave Pass Dichroic Beamsplitter SWP-45-RS532-TP355.

Short Wave Pass Dichroic Beamsplitters

exhibit high transmission for a short

wavelength band, high damage thresholds,

and high reflectivity for a longer band of

wavelengths.

Reflectivity bandwidth is limited by

coating design, incidence angle, and

polarization. For typical bandwidth

values l 155. To order, complete the

ordering blocks as shown below.

For additional substrate options l 183-195.

For high energy laser applications, specify

pulse energy, pulse duration, repetition

rate, and beam diameter.

For maximum transmission, when

R > 248nm then T should be > 248nm

and when R < 248nm then T can be

anything > 193nm. Call CVI technical

sales for further information

How To Order PW-1025-CTP 633RS 106445SWP

Product Code

Angle of Incidence in Degrees

Reflected Wavelength in nm with Polarization

Transmitted Wavelength in nm with Polarization

Substrate Part Number




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Broadband Low GVD Ultrafast Mirrors Wavelength Radius of Part Number Range (nm) Reflectivity Diameter Thickness Curvature

700-825nm

LGVD-700-825-1025 700-825 R >99.8% 1.00" 0.250" Flat

LGVD-700-825-1025-0.05CC 700-825 R >99.8% 1.00" 0.250" 0.05mCC

LGVD-700-825-1025-0.10CC 700-825 R >99.8% 1.00" 0.250" 0.10mCC

LGVD-700-825-1025-0.50CC 700-825 R >99.8% 1.00" 0.250" 0.50mCC

LGVD-700-825-1025-1.00CC 700-825 R >99.8% 1.00" 0.250" 1.00mCC

LGVD-700-825-1025-2.00CC 700-825 R >99.8% 1.00" 0.250" 2.00mCC

LGVD-700-825-1025-4.00CC 700-825 R >99.8% 1.00" 0.250" 4.00mCC

775-900nm

LGVD-775-900-1025 775-900 R >99.8% 1.00" 0.250" Flat

LGVD-775-900-1025-0.05CC 775-900 R >99.8% 1.00" 0.250" 0.05mCC

LGVD-775-900-1025-0.10CC 775-900 R >99.8% 1.00" 0.250" 0.10mCC

LGVD-775-900-1025-0.50CC 775-900 R >99.8% 1.00" 0.250" 0.50mCC

LGVD-775-900-1025-1.00CC 775-900 R >99.8% 1.00" 0.250" 1.00mCC

LGVD-775-900-1025-2.00CC 775-900 R >99.8% 1.00" 0.250" 2.00mCC

LGVD-775-900-1025-4.00CC 775-900 R >99.8% 1.00" 0.250" 4.00mCC

< 10fs2 GVD and < 100fs3 cubic term dispersion over 125nm bandwidth

700-825nm and 775-900nm standard wavelength regions

Other center wavelengths, dimensions, and radii of curvature available

Tavg > 90% for 488-532nm Argon-ion and Nd:YAG pump wavelengths

Mirror mounts are available l 357

Broadband Low GVD Mirrors LGVD

GVD and cubic term dispersion of LGVD Series Ultrafast Mirrors.

λ µ

Ωωω

φ

Ω

φ

Ω

φ Ω

φ Ω







Wedge ≤ 5 minutes







Angle of Incidence 0-20°

Damage Threshold 100mJ/cm2, 50fsec pulse at 800nm typical

Product Code

Wavelength Range nm

Size Code

Radius in Meters

How To Order 2.00CC1025700-825LGVD

LGVD




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Beamsplitters

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irrorsW

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Prisms

Window

sIntro

Low loss, prismless chirp compensation for femtosecond laser systems

Peak correction of -100fsec2/bounce Available at any center wavelength

from 450 to 2000nm

TNM2

Calculated vs actual group velocity dispersion of a TNM2 Series mirror.

Negative GVD Mirrors



Surface Quality 10-5 CVI Laser Quality defined on page 430



Wedge ≤ 5 minutes







Angle of Incidence 0-20°

Damage Threshold 100mJ/cm2, 80fsec pulse at 800nm typical

Ti:Sapphire and other femtosecond laser

systems need prismless compensation of

the built-in positive chirp encountered

in the laser optical circuit. This becomes

mandatory in industrial and biomedical

applications where the laser must provide

a compact, stable, and reliable solution.

TNM2 Series Negative Group Velocity

Dispersion Mirrors meets these needs

with off-the-shelf. TNM2 mirrors can be

employed both intra and extracavity to

satisfy chirp control requirements.

In experiments, 200mW, 80 fsec pulses

centered at 785nm were achieved in a

simple, prismless, Ti:Sapphire oscillator.

The configuration is shown in the diagram.

Negative Group Velocity Dispersion (GVD) Mirrors Wavelength Radius of Part Number Range (nm) Reflectivity Diameter Thickness Curvature TNM2-735-835-0537 735-835 R >99.8% 0.50" 0.375" Flat

TNM2-735-835-0537-0.05CC 735-835 R >99.8% 0.50" 0.375" 0.05mCC

TNM2-735-835-0537-0.10CC 735-835 R >99.8% 0.50" 0.375" 0.10mCC

TNM2-735-835-0537-0.50CC 735-835 R >99.8% 0.50" 0.375" 0.50mCC

TNM2-735-835-0537-1.00CC 735-835 R >99.8% 0.50" 0.375" 1.00mCC

TNM2-735-835-0537-2.00CC 735-835 R >99.8% 0.50" 0.375" 2.00mCC

TNM2-735-835-0537-4.00CC 735-835 R >99.8% 0.50" 0.375" 4.00mCC

TNM2-735-835-1037 735-835 R >99.8% 1.00" 0.375" Flat

TNM2-735-835-1037-0.05CC 735-835 R >99.8% 1.00" 0.375" 0.05mCC

TNM2-735-835-1037-0.10CC 735-835 R >99.8% 1.00" 0.375" 0.10mCC

TNM2-735-835-1037-0.50CC 735-835 R >99.8% 1.00" 0.375" 0.50mCC

TNM2-735-835-1037-1.00CC 735-835 R >99.8% 1.00" 0.375" 1.00mCC

TNM2-735-835-1037-2.00CC 735-835 R >99.8% 1.00" 0.375" 2.00mCC

TNM2-735-835-1037-4.00CC 735-835 R >99.8% 1.00" 0.375" 4.00mCC

TNM2




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TFPK

TFPKLow Dispersion Polarizers

Ideal for intracavity use in femtosecond regenerative amplifiers

Low group velocity dispersion for ultrashort femtosecond applications

Custom wavelengths from 250 - 1550nm, call for details

(University Science Books, Mill Valley,

California, 1986), for a good discussion of

linear pulse propagation.

In chirped pulse regenerative

amplification, the pulse may have to pass

through one or two polarizers twice per

round trip. There can be 10 to 20 round

trips before the gain is saturated and the

pulse is ejected. At this stage the pulse is

long (100ps-1000ps) and the phase shift at

each frequency must still be maintained to

minimize the recompressed pulse width.

The many round trips of the pulse in the

regenerative amplifier place stringent

requirements on the phase characteristics

of the coatings.

Shown are the power transmission

curves for S and P polarization and the

transmitted phase characteristics of the

P component for a TFPK optimized at

800nm. The phase characteristics shown

are the group velocity dispersion (GVD)

and the cubic phase term. Not shown

are the reflected phase characteristics for

S; they are similar to the P transmission

curves, also having low nonlinearity and

broad bandwidth. Note that both sides

of the optic are coated. Therefore, the

S and P transmissions per surface should

be squared in order to determine the

specifications. The phase characteristics

show that in all modes of operation, the

TFPK polarizer performance is dominated

by the substrate.

There are some subtleties associated

with the TFPK. The near 72° angle has

to be set properly and optimized. Some

thought has to be given to mechanical

clearances of the laser beam at such a

steep incidence angle. The reflectivity

for S is limited to 75%. Variant designs

can increase this at a slight loss in

bandwidth, increase in incidence angle,

and/or increase in insertion loss for the

transmitted P component.

Angle of Incidence 72° ± 2°

Wavelength 400nm or 800nm. Custom wavelengths available.

Bandwidth See curve for 800nm performance. Consult CVI for

bandwidths at different center wavelengths.

Extinction Ratio TP2/TS

2 > 15:1 where TP and TS are per surface

transmissions

Reflection Efficiency RS > 75% each surface. S reflectivities of 85% and

95% available at some sacrifice of P transmission.

Working angle of incidence will increase. Consult

CVI for specifics.

Transmission Efficiency TP > 98% each surface. Slight tilting required to find

angle of minimum loss.

Properties for one coated side of a TFPK polarizing beamsplitter optimized for 800nm. Both sides are coated for these properties.

CVI has developed the TFPK Low

Dispersion Polarizing Beamsplitters to

satisfy requirements for very high power,

short pulse lasers. These optics are

ideal for intracavity use in femtosecond

regenerative amplifiers. The main

emphasis is on linear phase characteristics.

See Chapter 9 of Lasers, A. E. Siegman

Product Code

Center Wavelength nm

400 800

Substrate Part Number l 15-25

How To Order RW-28.6-14.3-3.2-C800TFPK




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sIntroIB Isosceles Brewster Prisms

IB

φ

GVD correction prisms for

femtosecond systems

Two sides (AB) optically polished

Suprasil 1 useful to 170nm

Extremely small loss for

P-polarized beam

Other dimensions and material

available

* Dimension is to theoretical sharp

Isosceles Brewster Prisms Altitude Dimension Dimension Dimension Apex Refractive Part Number H (mm) A (mm) B* (mm) C* (mm) Angle φ Material Index @633nm IB-10.5-68.7-SS 10.5 7.9 12.7 14.4 68.7° Suprasil 1 1.45702

IB-15.0-68.7-SS 15.0 12.7 18.2 20.6 68.7° Suprasil 1 1.45702

IB-19.0-68.7-SS 19.0 12.7 23.0 26.0 68.7° Suprasil 1 1.45702

IB-12.4-69.1-UV 12.4 15.0 15.0 17.0 69.1° Fused Silica 1.45702

IB-13.0-59.2-LaFN28 13.0 15.0 15.0 14.8 59.2° LaFN28 1.76988

IB-12.8-63.0-LaKL21 12.8 15.0 15.0 15.7 63.0° LaKL21 1.63821

IB-13.0-60.6-SF10 13.0 15.0 15.0 15.1 60.6° SF10 1.72307

IB-21.6-60.6-SF10 21.6 25.0 25.0 25.2 60.6° SF10 1.72307

Dispersing prisms are used to separate a

beam of white light into its component

colors. Generally, the light is first

collimated and then dispersed by the

prism. A spectrum is then formed at the

focal plane of a lens or curved mirror.

In laser work, dispersing prisms are used

to separate two wavelengths following the

same beam path. Typically, the dispersed

beams are permitted to travel far enough

so the beams separate spatially.

A prism exhibits magnification in the

plane of dispersion if the entrance and

exit angles for a beam differ. This is useful

in anamorphic (one-directional) beam

expansion or compression, and may be

used to correct or create asymmetric

beam profiles.

For more information on the usage of

these prisms, see the technical discussion

“Prisms” l 267.

Limited stock of LaFN28 and LaKL21 still

available. Call for pricing and delivery.

Substrate Material Suprasil 1, UV grade fused silica, LaFN28, LaKL21,

or SF10 glass


Surface Quality Suprasil 1 and UV grade fused silica:

10-5 CVI Laser Quality defined on page 430

LaFN28, LaKL21, and SF10 glass:

30-10 per MIL-PRF-13830B

Dimensional Tolerance + 0.00mm, − 0.25mm

Angular Deviation ± 2 minutes



Damage Threshold Suprasil 1: 15J/cm2, 20ns, 20Hz at 1064nm

Fused Silica: 15J/cm2, 20ns, 20Hz at 1064nm




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FABS Autocorrelator beamsplitters

are broadband, 50% all-dielectric

beamsplitters. They are useful in many

types of pump-probe experiments and

in the construction of anti-resonant ring

configurations. They are essentially

lossless and extremely durable. Both are

advantages over partially reflecting metal

coatings.

Shown here are power transmission

curves for the S and P polarized versions

with the corresponding reflected phase

characteristics for beamsplitters optimized

at 800nm. The linear pulse propagation

properties of these beamsplitters are

dominated by the substrate material

dispersion. As with virtually all dielectric

coated optics, the S polarized version

is broader than P polarized. CVI can

produce FABS in other than 50:50 with

excellent phase characteristics.

Femtosecond Beamsplitters FABS

Angle of Incidence 45°

Polarization S or P. User must specify. Bandwidth is greater

for the S polarized version.

Wavelength Band See curves below for 800nm performance. Consult

CVI for bandwidths at 400nm.

Reflectivity Near 50%, first surface. Second surface,

broadband antireflection coating optimized

for requested polarization.

Transmission [1 - R] first surface.

Substrate Material User specified. Standard wavelengths of 400nm and 800nm

Standard mirror substrates l 183-195 Standard size and radii l 428

Product Code

Center Wavelength

Angle of Incidence with Polarization

Substrate Part Number

How To Order PW-1006-UV45P800FABS

The curves above represent the performance of two distinct beamsplitters. Beamsplitters for both S and P polarizations must be specified separately.

FABS-800-45P FABS-800-45S

FABS



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