Phosphate laser glass of absorption loss of 10−4cm−1

Phosphate laser glass of absorption loss of 10−4cm−1

Journal of Non-Crystalline Solids 95 & 96 (1987) North-Holland. Amsterdam PHOSPHATE LASER H. Toratani, Hoya Optics, T. GLASS H. E. Inc., Izumita...

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Journal of Non-Crystalline Solids 95 & 96 (1987) North-Holland. Amsterdam

PHOSPHATE

LASER

H. Toratani, Hoya Optics, T.

GLASS

H. E. Inc.,

Izumitani,

S. E. Stokowski, California 94550,

701

OF ABSORPTION

Meissner Fremont,

Hoya

701 - 708

California

Corporation,

94538,

Tokyo,

Lawrence U.S.A.

OF 10-4cm-1

LOSS

Livermore

+

U.S.A.

Japan National

Laboratory,

Livermore,

We have experimentally determined loss coefficients of OH as 8.1x10-7cm-1/ ppm and of ionic platinum as 8.6x10-7cm-I/ppm for LHG-5 type phosphate laser glass without Nd203 doping. Glass has been produced with absorption loss of about 1x10-4cm-I which is one order of magnitude lower than is presently commercially available.

1. INTRODUCTION Lower

absorption

loss

and

an

increase

in

ful

for

diode

pumped

duced

phosphate

(430-650

loss

work

in

fibers

produced

phosphate' have of

been

glass

Losses

are

originating from

the

but

efforts positions

2.

loss

EXPERIMENTAL

2.1. A glass

+Supported

Glass

of

by

4f

laser

LHG-5,

and

-1

reduction silica

of glass

silicate'

and

applications to

metal

due

of due

glass

to

scalable

transition

absorption

by absorption

10-4cm-1

cm

lasers. the

fiber

readily

-3

to 1.5x10

multicomponent optical

pro-

large

shapes

slabs.

3d and

scattering for

to

is

or

materials; and

Hoya's

to

OH groups,

to

glass

of

high

(43

dB/km)

for

on

factors

ions,

Pt ion, depending

imperfections

quality.

mainly

introduced on

We report

commercial

contributing

melt-

causes

laser to

on glass

our com-

it.

PROCEDURE melting

composition

in

processes

1.0

relates

of for

use-

Currently

neodymium

majority

examples

plates

addition,

negligible

as

these

absorption

batch

material;

reduce such

of

of

thresholds

particularly

addresses

10 dB/km

than

losses of

lasing are

lasers.

literature the

lower loss

slab

wavelength the

some

less

amplifier

by

the

In are

to

as

caused

crucible

the in

process,

low

typically

is

in

of

zig-zag

Although

loss None

such

conditions.

losses

a CVll

with

from

exhibit

fibers.

reported.

laser

ing

by

glass

large

discussed

glass

results

Glasses

1.05um which

at

medium

apd

glasses

previously

optical

a lasing

efficiency.

miniature

laser

dB/km)

Most

of

slope

part

of

by

65

Lawrence

P205

-

12.5

Liver-more

A1203

National

0022-3093/87/.$03.50 0 Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)

- 22.5

Na20

Laboratory

(in

mol

'd) was

em-

H. Tornroni

702

ployed

for

with

the

Table

small

scale

composition

1 shows

suppliers.

1200°C

in

metal

experiments of

the All

coaniercial

impurity

content

glasses

furnaces

er 01. / Phosphore

were

which

while

larger

LHG-5

in

of

melted

were

scale

batch

Pt or

designed

to

gkm

melts

a prototype

glass in

her

were

materials

fused

carried

production as obtained

quartz

minimize

out

furnace. from

crucibles

at

contamination

by

about

transition

ions. Impurity

1

Table H3P04

contents

Fe

<

A1('N3

50

in

ppb

batch

materials < 50

Cu

< 300

ppb

< 50

NaN03

<

10

<

1

Na2C03

<

10

c

1

2.2.

Platinum

dissolution

To evaluate ial,

the

mined for

the

rate

at

of

preliminary

of

melts 3.

of

excluded the

EXPERIMENTAL Dissolution

Table

2 lists

was

of

optical

the

fused

inserted

crucible

quartz into

cleaned

9) was the

used

the

with

sample

is

mater-

was

deter-

melt

and

acid

measure

and

kept

its

absorption

detection

required

of

our

10 cm long

were

to

minimum

quality of

10-4cm-1

rate

rate

for

commercial to

Lamda

a 10 cm long

Pt

crucible

level for

glass

as

for

a 1 cm

determining

samples

in

a small

scale

samples.

measured

3

calorimetrically.

rates is

fused

contains

Pt the

Pt

dissolution

(1.1x10-‘cm/set)

grade

grade

materials

and

1200°C,

contaminate

purity

of

TM impurities

at

ventional

higher

of

remoyed,

Since

measurements

order

(2.3x10-7cJsec)

expected

from

that

RESULTS

3.1.

the

Elmer

' The poor reliable

of

Although

was

samples.

1x10-3cm-1

is

1x10-4cm-1.

Losses

as

plate

plate

(Perkin

evaluation

sample

quartz

the

originating

as well

measurement

A spectrophotometer

loss

fused

Then,

TM ions

Pt

imsasured.

Loss

long

glass

Pt and of

A Pt or times.

loss

2.3.

of

dissolution

12OO'C.

different

weight

in

effect

quartz

(99.95%).

glass

(99.99%)

lower

Pt

introduces

by

about

OH content

on

loss

crucible of

one

fused

for

quartz than

con-

materials

TM ions.

order

quartz.

fused

TM impurities

both levels

and

that

less

Therefore,

by comparable

of than

of

are

However, magnitude

lower

TM contents. 3.2.

Effect

Table

3 shows

calorimetric

of

OH the

measurements.

effect

of

at

1.05um

as obtained

from

H. Toromni

Table

2

TM impurities

Impurity

and

(ppm)

Dissolution

rate

Dissolved

content*

(wb)

Table

10 liter

3

of

glass

of

crucible

rate

703

materials

99.95%Pt

99.99%Pt

Fused

Fe

20

2

1

cu

5

1

0.16

o.17x1o-g

2.ox1o-g o.3x1o-g

Fe

1.7x1o-g

cu

o.43x1o-g

O.O8x1O-g

1.3

0.1

1.6

cu

0.33'

0.07

0.25

10 hrs

OH content

melting

on

Absorption la 3.35um

loss

Otl content*

cm-l

990

Loss

1

33.0

2

12.6

380

3

3.0

90

1.19

4

2.0

60

2.02

5

2.3

70

1.15

6

1.4

40

1.13

* OH content

is

estimated

quartz

2.3~10-~

Fe

crucible,

Effect

laser

1. 1x1o-g

(g/cm'/hr)

*

dissolution

(cm/s)

impurity

Impurity

er al. / Phosphate

ppm

@ 1.05um

8.9x10-4cm-1 3.2

as OH (ppm)

(cm-l)

= 3O.a

Ref.4

3.35um We estimate versus 100

the

OH content OH ppm appears

loss

coefficient

due

as 0.81x10-6cm-1/ppm to be insignificant

to

the

OH group

from

at 1.05um (Fig. 1). for obtaining levels

loss.

10

I

I

250

I

500

750

OH content FIGURE

1

Loss

coefficient

(ppm) due

to

OH

I

1000

a plot

of

loss

Loss due of 10 -4

to -1

OH below

cm

overall

704

H. Toramni

3.3.

Effect

Table

4 indicates

tribution is

of

below

of

the

ionic

ef al. / Phmphore

laser glass

platinum

the

effect

OH group

is

of

ionic

platinum

negligible

on

because

the

loss

at

1.05um.

OH content

of

The

these

con-

glasses

70 ppm.

. Table

4

Effect

of

Ionic

1

platinum

Pt

0 wm

on

loss

OH Content

Loss

40

1. 1 - 1. 2x10v4cm-l

- 70 ppm

200

70

3.0

3

500

40

5.44

We determine platinum

which

is

a loss of

almost (Fig.

of

platinum

ionic

ppm to

coefficient

about the

OH group

same

2).

due

as

that

Therefore, should

produce

the

be

a glass

_ the

‘:

content

d

of

less

than

with

3.4.

Effect

The ing

loss

time

after

of

at

does

not

17 hours

furnace

furnace

1.05um exhibit

loss

5). does

amounts

glass

of

of

melteven

Evidently, not

4

200 Ionic

to

FIGURE

5

Effect

Melting

lates

furnace

environment

time

on

OH Content

2

ionic

Loss

2 hrs

90

7

60

1.15

3

17

45

1.13

Prototype

the

we have for

geometry

coefficient

due

at

1.05um

wm

melts

point,

conditions

Loss platinum

1. 19x10e4cm-l

1

this

500 (ppm)

loss

2

3.5.

cess

of

Pt

the

to

At

0 i-----"

contribute

contaminants

8.6~10~~

t

the

melt.

Table

Slope:

$5 A .w m z

environment

change

1

10

b z.

about

overall

function any

(Table

environment

significant

as

1.05um

to

0.84x10-6cm-1/ppm

1x10-4cm-1.

of

at

82

ionic

100

ionic

attained

melting of

commercial

glass

sufficient in scale

a 0.5

understanding liter

production

prototype melters.

about

necessary

furnace

which

The

results

prosimusuggest

H. Toraroni

that

phosphate

laser

fully

produced

plates

when

4.

DISCUSSION

Table

1 lists

loss

of

10-4cm-1

able

as

laser

140

ppb

due loss

at

These

in impurity

1.05pm

laser

high

can

slabs

be

success-

and

amplifier

purity.

Co'+,

vary

with

be

for

Co'+,

glass

and

be

for

Ni2+

ppb

the

valence

dissolve to

less

in

ultra-

To achieve which

are

suit2+

than

47

ppb

for

Cu

and

590

ppb

for

V3+

re-

of

ions.

state

metallic 3+ Fe which

V3+

glass.2

compositions

should

350

converted

Ni2+,

a P205-Ge02-Ga203

content

for

ions Fe2+,

ultraphosphate

to

will

Cu2+,

data

the

2+

metal of

conditions Fe

705

at for

of

transition

1.05um

values

glass

TO LOSS 3d

ppb

required

materials

available

280

oxidizing most

to

and

Fe2+,

spectively.

Therefore,

batch

lawr

1x10-%m-1

of

shapes

coefficients

glass,

for

in

and

commercial

glasses5

melted

a loss

with

volume

OF CONTRIBUTIONS

Absorption

at

the

using

4.1.

phosphate

glass

in

er al. / Phosphore

platinum is

Laser

glass 6

inclusions.

known

to

absorb

,

is

less

1.05um. Table

6

Loss

coefficient

of

Loss

coefficient

Ion

2.4~10-~

Fe2+

0.7

2.4

co2+

0.35

Ni2+

0.28

v 3+

0.17 Ultraphosphate

B:

51.5P205-18.5Ge02-30 1 shows

about

loss 2.7x10

This

Table

5),

maximum loss

tribution crucible

68.2P205-1

their

1.8A1203-14

Ga203

the

maximum

contribution -4 -1 when cm , consistent

assuming

2,

mol

%)

5

that

(in

at

K20-6

content

1.05pm

applying the

(La+Nd)203

(in

%)

impurity

with the

wt

of

from the

the

batch

same

loss

of

impurity

6 also

allow

used,

Table

6 as

coefficients

calorimetrically

actual

materials

coefficients

to

measured concentrations

our

total were

loss

below

the

levels.

coefficients of

.

is

glasses

1.1

A:

Table

phosphate

(cm-l/ppm) B

than

The

in

2.3~10-~

composition.

stated

ions

A

Since

(e.g.

metal

cu2+

we estimate less

transition

of

impurities Using

which

experimentally

Table are

dissolved determined

an out

of

dissolution

assessment a platinum rates

of

the

maximum

or

fused

for

Pt

quartz and

fused

con-

706

H. Toramri

quartz

(Table

liter

2)

melt

terials. of

Therefore,

earth

due

extent

which

large

amounts

may not

be negligible.

efficient

is

3/2

which

Boltzmahn

cross

section

a weak

However,

equals

with

this

the

the

ground

the

is

that

at

1.05um

level,

is

5~10~’

10~10~~

1x1o-3

2x1o-3

a real

loss

case,

purer

but

to

by:

only

ions,

with

Nd203

should

99.99%

Since

the

10 weight

%

a loss

co-

be

used.

41 4

11/2level

I11,2

population

cross

given

but

with

as

transition

total

1.05um

for

such

the

thermal of

concentration

1~10~’

2 ppb

relatively

ppm even

levels

due

at

contains 100

harmful

emission

2x1o-4 not

often

most

the 5~10~~

stimulated

Nd203

are

transition.

coefficient

increasing

loss introduced

doping

In

about

ma-

since

They

20 to

the

lasing

is

to

Absorption

The

is

1.1

and

bands

suggests

of

Nd3'

ions.

The

absorption

section

which

is

due

about

k = Nox5x10-5x4x10-20

approximately

a decrease

of

as

inversion

shown:

density

in

0.97um.

although

2.87um

the

achieve on

efficient

not

loss data at

experimental

of of

value

should of

Absorption

due

absorption

bands to

and

affect

to

the

3.4,

presumed

This

less

than

of of

-1

, and

the is

1.44,

to

loss

is

at

2h30

absorption consistent

ppm co-

with

platinum to at

ionic 1.05um

platinum for

at higher

around

0.300

Pt

concentrations.

and

3.4

tolerable

ppm OH. 4

100

OH

at

mode

which

approximately

that

1 cm

coupled cause

fundamental

be

wave1.8,

absorption

likely to

OH groups to

indicates

about

is

the

various 2.0,

observed

effective

edge

at 2.6,

and mode

most

content

is

fibers 2.87,

predicted

absorption

1.05um

ionic

loss

optical

are

The

than

due

in about

vibration 1.1

fiber.

be

less

Broad

appear

of

glass

4.4.

3)

stretching

0.97

effect

loss at

between

be negligible. 10 -4 cm -1 at

silica

3.4um

of

observed

P-O-P at

the

will

a source are

A comparison

Absorptions

1.05um

OH

as

bands

that

vibration.

to

known

Absorption

1.28,

based

due

OH group

lengths.

(Fig.

are

platinum

Pm3+ increase

Nd203

Nd203

Sm3'

a 10

crucible

pumping.

4.3.

to

of

above

k (cm-')

optical

and

high

pure

the

ions

e.g.

absorption

inverse

N,(ions/cc)

and

3+

The absorption

increases

Since

in

of

level.

ions.

oxides, at

distribution

4x10-20cm2. and

ion. earth

l.lx10-5cm-1/ppm.

the cm -1

2000

the

metal

any

99.99%

Sm3+ and metal

active

Oy

use

for

10 -4 cm -'

as Oy 3+,

rare

has is

the

impurities

2 ppb

to

transition

contribution

about

itself

about

to

loss

of

Nd203

the

dissolved

than

3d transition

other

their

4f

at

laser glass

totally

less

necessary

such

provides

puri;y,

not

to

than

of

to

loss

impurities

a lesser

Nd203

is

affect

Absorption

Rare

of

amounts

it

do not

4.2.

4F

concentration

10 hrs

impurities

to

the

after

er -1. / Phosphore

0.43Oum The

our

H. Tororoni

ausorption fier

coefficient

of

in

fusion

discs

responds

to

laser

of

efficiency

0.2cm-1

and

(

of

100

total

ppm is

loss 100

at

systems

a concentration

concentration

CI al. / Phosphore

JUU

nm is

in

about

130

g/au

707

currently

terms

of

from

accepted

pumping

ppm of

acceptable -4 -1 10 cm .

of

her

ionic

the

for

ampli-

efficiency.

This

platinum.

viewpoint

' of

cor-

Therefore

both

the

pumping

Ionic

Pt

free

Thickness

of 1Onm

samples

1 400

FIGURE

5.

600

Wavelength

(nm)

Absorption

due

to

700

ionic

platinum

CONCLUSIONS Using

laser the

3

500

commercially glass

of

production Various

of

factor

ions

in

is

batch

which content

of

affect

loss

materials.

by

and

choosing

at

shapes

of

0.Blx10-6cm-1/ppm

controlled

purest loss

larger

factors

tant

about

available

1.1x10-4cm-1

batch 1.05pm laser at

impurities

such

The

of

effect

materials, in

slabs

and

1.05um as the

which

amplifier

were 3d

evaluated:

and

phosphate

scalable

The metal

of

respectively.

melting

melted is

to

discs.

transition

OH group

0.B6x10-6cm-1/ppm

appropriate

we have

a furnace

ionic Both

and

most

impor-

rare

earth

platinum

are

of

are

these

conditions.

ACKNOWLEDGEMENT We would measurements,

like

to and

A.

thank Pertica

F. Milanovich for

determining

and

R.

Robe1

some

of

for

the

the

absorption

calorimetric

loss spectra.

708

H. Tora~oni

el al. / Phosphare

laser glass

REFERENCES 1)

M. Yoshiyagawa, (1980) 489.

2)

T. Akamatsu,

3)

F. Milanovich E. Day

Y.

J.

Lightwave

and and

J.

Kaite,

R.

4)

0.

5)

S. E. Stokowski Society Symposia

6)

Laser Program Annual Liver-more, California,

Robel,

M. Stevels,

T.

Ikuma

Tech., to J.

and D. Kraskevich, Proc. 61 (1968) Report 1985, UCRL-50021-85

and

LT-1 be

T.

Kishimoto,

(1983)

J.

Non-Cryst.

Solids

580

published.

Non-Cryst. Defects 273. Lawrence (1985),

Solids, in

14

Glass,

Liver-more pp. 6-17

(1974) Materials

National to 6-21.

165. Research

Laboratory,

40