1. Erbium Microchip Laser Development 1.Erbium:Yb:Glass and Er:Yb:LiNbO3 Status. 2.Problems with 980 nm Laser Pump. 3.Development Plans.

2. Erbium,Yb:Glass No lasing using external cavity test setup. Doping levels appear reasonable for a short (e.g., 0.5 mm or less) chip length. Pump beam diameter too large/power too low. Cavity mode diameter too large due to long distance between external mirrors.

3. Er,Yb:LiNbO3 No new information – still trying to determine doping levels and reasons for excessive up-conversion losses. Currently concentrating on Er,Yb:Glass development.

4. Current Plans 1 Have VLOC provide the following: 1.0.5 mm thick Er,Yb:Glass micrchips with integral HR (rear) mirror, and AR coated front surface for use with external small radius (e.g., 5 to 10 mm) OC mirror. 2.0.5 mm thick Er,Yb:Glass micrchips with integral HR (rear) mirror, and OC (front) mirror. 3.2.9 mm thick Mg doped LiNbO3 with and without OC mirror on one end for use with (1), above. 4.Several smaller thicknesses and possibly several doping levels of (1).

5. Current Plans 2 Microchips with both HR and OC mirrors should lase up against pump diode or fiber, or with at most simple focusing optics. This will confirm correct doping levels and provide a way of testing performance Microchips with only HR mirror will be tested in a short cavity small radius (e.g., 5 to 10 mm) mirror and when mated with the LiNbO3 section result in an composite crystal suitable for mode locking.

6. Configurations for Basic Lasing Tests

7. Configuration for Mode-Locked Laser

8. 980 nm Pumps We have ordered a high quality laser diode driver system to replace the one we have that tends to blow out expensive pumps! We have ordered several 1 W fiber coupled pump diodes. The 125 um fiber core diameter is small enough that simple focusing optics should be adequate for the thin Er,Yb:Glass microchips. We will be mounting several bare 1 W 980 nm pump diode chips.

9. Summary Obtain new Er,Yb:Glass micrchips. Putting together new pumps. Quite confident that these will result in lasing.

10. Existing and New 980 nm Pumps