THORLABS ULN15 Series, User Manual, Page: 10 / 24

Ultra-Low Noise Laser Chapter 3: Description
Page 8 QTN039956-D02
3.2.2.
“T” Configuration – Optimized for Longer-Range Temperature Tuning
The T configuration allows for independent adjustment of T
FBG
without impacting
the laser’s output power.
However, the current span of each mode-hop free range is considerably reduced in the T configuration. Users
requiring the maximum possible mode-hop free tuning and/or current range should select the C configuration.
Figure 5 shows a typical LI curve for a T-configuration device. The reduction in the size of the single mode ranges
can be seen when compared to the C-configuration device behavior shown in Figure 1. OSA measurements of
the spectrum are shown at various T
FBG
in Figure 7. The tuning of the center wavelength is shown in Figure 8. It
should be noted that the single mode regions do move as T
FBG
is adjusted, as shown in Figure 6; a ULN kept at a
single current will therefore not operate single mode at all temperatures. To ensure continued single mode
operation, we recommend monitoring the laser’s output with an OSA.
Figure 5 LI Measurement of a T-Configuration ULN at Constant T
FBG
0 100 200 300 400 500 600 700 800
0
20
40
60
80
100
120
140
160
180
Increasing Current
Decreasing Current
Single Mode Operating Regions
Power (mW)
Current (mA)