Diode-Pumped Er,Yb:Glass Micro-Laser - Kigre, Inc.
Diode-Pumped Er,Yb:Glass Micro-Laser - Kigre, Inc.
Diode-Pumped Er,Yb:Glass Micro-Laser - Kigre, Inc.
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Presentation to the 2002 Meeting of the<br />
Advanced Solid-State Photonics Conference<br />
Feb 3, 2003<br />
<strong>Diode</strong>-<strong>Pumped</strong> <strong>Er</strong>,<strong>Yb</strong>:glass <strong>Micro</strong>-<strong>Laser</strong><br />
C. Ward Trussell<br />
Vernon King<br />
Alan D. Hays<br />
J. Andrew Hutchinson<br />
Night Vision & Electronic Sensors Directorate, US Army CECOM<br />
Scott J. Hamlin<br />
MegaWatt <strong>Laser</strong>s, <strong>Inc</strong>.<br />
PO Box 24190<br />
Hilton Head Island, SC 29925-4190<br />
shamlin@hargray.com<br />
MegaWatt <strong>Laser</strong>s
Eyesafe <strong>Laser</strong> Rangefinder<br />
Transmitters Requirements<br />
• Lightweight<br />
•Small<br />
• Low cost<br />
• Works over temperature<br />
• Battery operated, low power consumption<br />
• Single shot up to 10 pulses/sec.<br />
• Energy : 0.05 to 5 mJ<br />
• Pulse width: < 5 nsec<br />
MegaWatt <strong>Laser</strong>s
<strong>Micro</strong> Eyesafe Solid State <strong>Laser</strong><br />
<strong>Diode</strong>-<strong>Pumped</strong> <strong>Er</strong>,<strong>Yb</strong>:glass Approach<br />
Top View<br />
Q<br />
Switch<br />
<strong>Laser</strong><br />
<strong>Diode</strong><br />
<strong>Diode</strong><br />
Optics<br />
<strong>Er</strong>,<strong>Yb</strong>:<br />
<strong>Glass</strong><br />
Output<br />
Coupler<br />
1.5 micron<br />
pulses<br />
Side View<br />
End <strong>Pumped</strong> <strong>Laser</strong><br />
•Good pump/laser mode overlap<br />
•Long pump absorption length<br />
•Wide Temp range for laser diode<br />
•High Efficiency<br />
<strong>Er</strong>,<strong>Yb</strong>:glass<br />
•Direct 1.5 micron output (no OPO)<br />
•Long fluorescence Lifetime(20x Nd:YAG)<br />
•Single stripe pump laser diode<br />
•Low cost material<br />
Performance Results:<br />
Single laser diode: 4 watts at 918nm, 4 milliseconds pump time, 16 mJ pump energy<br />
Energy Output at 1.54 microns: 105 to 140 micro-joules, 3 ns pulse, 10 Hz.<br />
Peak Power: 35 kW to 50 kW<br />
Electrical input: 40 mJ/pulse at 10 Hz = 400 mW<br />
MegaWatt <strong>Laser</strong>s
<strong>Diode</strong>-pumped <strong>Er</strong>,<strong>Yb</strong>:glass laser<br />
input and output parameters<br />
HR coating<br />
@ 1.54µm<br />
AR @ 0.94µm<br />
<strong>Laser</strong><br />
<strong>Diode</strong><br />
<strong>Er</strong>,<strong>Yb</strong>:glass<br />
AR coating<br />
@ 1.54µm<br />
HR @ 0.94µm<br />
PR coating<br />
%R @ 1.54µm<br />
Co:spinel<br />
<strong>Laser</strong> Pulse<br />
Power<br />
Pulse width<br />
Wavelength<br />
Pump beam area<br />
Intensity<br />
<strong>Yb</strong> 3+ concentration<br />
<strong>Er</strong> 3+ concentration<br />
Length<br />
Wavelength<br />
Energy<br />
Pulse width<br />
Pulse rate<br />
Co 2+ concentration<br />
Length<br />
Transmission @ 1.54µm<br />
MegaWatt <strong>Laser</strong>s
Ytterbium-<strong>Er</strong>bium Kinetics<br />
<strong>Yb</strong> 3+ , <strong>Er</strong> 3+ :Phosphate <strong>Glass</strong> System<br />
20<br />
3 cm<br />
-1 ]<br />
15<br />
4 F 9/2<br />
4 I 9/2<br />
Energy [X 10<br />
10<br />
5<br />
Pump<br />
2 F 5/2 <strong>Yb</strong> 3+ <strong>Er</strong> 3+ 4 I 15/2<br />
4 I 11/2<br />
4 I 13/2<br />
Lasing<br />
0<br />
2 F 7/2<br />
MegaWatt <strong>Laser</strong>s
<strong>Diode</strong> Pump Optics Design<br />
using ZEMAX<br />
Unit #2 Design<br />
New design with more<br />
uniform pump beam<br />
ZEMAX model by Jerry Franck<br />
MegaWatt <strong>Laser</strong>s
<strong>Diode</strong> <strong>Pumped</strong> <strong>Er</strong>:<strong>Yb</strong>:glass <strong>Micro</strong>-laser<br />
Packaged in TO3 can<br />
MegaWatt <strong>Laser</strong>s
<strong>Er</strong>,<strong>Yb</strong>:glass micro-laser packaging design<br />
by Alan Hays (NVESD)<br />
MegaWatt <strong>Laser</strong>s
<strong>Yb</strong> 3+ Absorption with Temperature<br />
Shift of Pump <strong>Laser</strong> Wavelength<br />
-30 C to +50 C<br />
<strong>Laser</strong> <strong>Diode</strong> Temp Bandwidth<br />
MegaWatt <strong>Laser</strong>s
<strong>Diode</strong> <strong>Pumped</strong> <strong>Er</strong>:<strong>Yb</strong>:glass <strong>Micro</strong>-laser<br />
Recent results with TO3 package<br />
<strong>Micro</strong>-laser in TO3 package and<br />
<strong>Diode</strong> drive circuit for use with L123<br />
Battery.<br />
Oscilloscope traces showing diode pump current<br />
for 8 milliseconds and 7 q-switched pulses with<br />
approximately 80 micro-joules/pulse. Pulses are<br />
stretched for display. Actual pulse width is 2 ns.<br />
MegaWatt <strong>Laser</strong>s
Eye-Safe <strong>Laser</strong> Output Pulse<br />
MegaWatt <strong>Laser</strong>s
Beam Quality<br />
Beam Quality < 2.6 mm-mrad<br />
MegaWatt <strong>Laser</strong>s
Time to Q-switch Q<br />
vs. laser diode power<br />
NV01 glass<br />
Q/S Time-vs-Pump Power<br />
NV-01, 80% OC, 94%T Q/S (MO176), 2.8mm lens-lens, 1.6 mm vv200-glass<br />
Turn-on Time (mS)<br />
9<br />
8<br />
7<br />
6<br />
5<br />
4<br />
3<br />
2<br />
1<br />
0<br />
0 0.5 1 1.5 2 2.5 3 3.5<br />
Power (Watts)<br />
Pulsew idth (mS)<br />
MegaWatt <strong>Laser</strong>s
Eye-Safe <strong>Laser</strong> Environmental Test<br />
<strong>Er</strong>bium <strong>Laser</strong> Performance<br />
over Temperature<br />
10<br />
8<br />
Buildup Time, msec<br />
6<br />
4<br />
2<br />
0<br />
0 10 20 30 40 50 60 70 80<br />
Temperture, C<br />
MegaWatt <strong>Laser</strong>s
<strong>Diode</strong> <strong>Pumped</strong> <strong>Er</strong>,<strong>Yb</strong>:glass <strong>Micro</strong>laser<br />
Energy Histogram Data<br />
Pulse-energy Distribution<br />
% of 100 Shots<br />
14<br />
12<br />
10<br />
8<br />
6<br />
4<br />
2<br />
0<br />
<strong>Glass</strong>: B3<br />
Q/S: 94%T (5 mm diameter)<br />
OC: 80%R; 1 m ROC<br />
Q/S @: 4.5 mS of 5 mS pump<br />
P/W: 2.9 nS<br />
E(avg): 122 µJ<br />
Std. Dev.: 7.32 µJ<br />
104<br />
106<br />
108<br />
110<br />
112<br />
114<br />
116<br />
118<br />
120<br />
122<br />
124<br />
126<br />
128<br />
130<br />
132<br />
134<br />
136<br />
Energy (µJ)<br />
MegaWatt <strong>Laser</strong>s
<strong>Diode</strong> <strong>Pumped</strong> <strong>Er</strong>,<strong>Yb</strong>:glass <strong>Micro</strong>-<strong>Laser</strong><br />
Summary<br />
• Lightweight Eyesafe <strong>Micro</strong>-<strong>Laser</strong> developed for<br />
Rangefinder Applications: 12 gm<br />
• Wavelength: 1.54 µm for eyesafety<br />
• Energy: 80 to 140 µm<br />
• Pulse Width: 2.0 nsec<br />
• Peak Power: up to 50 kW<br />
• PRF: 1 to 20 Hz<br />
• Ranges up to 2 km demonstrated<br />
• Tested to 5 x 10 6 with No Degradation @ 60 ºC<br />
• Low cost projected<br />
MegaWatt <strong>Laser</strong>s
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