Page 175 - High Power Laser Handbook

144 Diode Lasers High-Power Diode Laser Arrays 145

Current 75 A
1.0
Without VBG@20°C 90%
With VBG@20°C
0.8
With VBG@25°C
Intensity (a.u.) 0.6 With VBG@35°C 50%
With VBG@28°C

0.4

0.2
10%
0.0
000 002 004 006 008 010 012 014
Wavelength (nm)
Figure 6.10 Laser diode bar wavelength-locked at 808 nm while operating
at 75 A from 20–35°C.

4500
4000 20 A, 0409–1319 w/o filter
30 A, 0409–1319 w/o filter
3500 40 A, 0409–1319 w/o filter
20 A, 0409–1319 filter
3000
Relative power 2500 40 A, 0409–1319 filter
30 A, 0409–1319 filter
2000
1500
1000
500
0
800 802 804 806 808 810 812
Wavelength (nm)

Figure 6.11 Spectral stability of diode laser with respect to operating
current.

6.5.4 Lifetime and Reliability
The mean time to fail (MTTF) of a 50-W, CW-mode, 808-nm diode
laser bar on a passively cooled heat sink is about 20,000 hours. The
same bar 10 years ago would have barely lasted a few thousand
hours. This tenfold increase in diode lifetime over the past decade is
a result of continuous improvements in all process steps in the manu-
facturing of the packaged diode laser bar. Improvements in the epi-
taxial design, wafer processing, facet coating, facet passivation, diode