文档介绍：Application Note 89
April 2001
A Thermoelectric Cooler Temperature Controller
for Fiber Optic Lasers
Climatic Pampering for Temperamental Lasers
Jim Williams
INTRODUCTION
Temperature Controller Requirements
Continued demands for increased bandwidth have re-
sulted in deployment of fiber optic-works. The The temperature controller must meet some unusual
fiber optic lines, driven by solid state lasers, are capable of requirements. Most notably, because of ambient tempera-
very high information density. Highly packed data schemes ture variation and laser operation uncertainties, the con-
such as DWDM (dense wavelength division multiplexing) troller must be capable of either sourcing or removing heat
utilize multiple lasers driving a fiber to obtain large multi- to maintain control. Peltier-based thermoelectric coolers
channel data streams. The narrow channel spacing relies (TEC) permit this but the controller must be truly bidirec-
on laser wavelength being controlled within (na- tional. Its heat flow control must not have dead zone or
nometer). Lasers are capable of this but temperature untoward dynamics in the “hot-to-cold” transition region.
variation influences operation. Figure 1 shows that laser Additionally, the temperature controller must be a preci-
output peaks sharply vs wavelength, implying that laser sion device capable of maintaining control well inside
wavelength must be controlled well within to main- °C over time and temperature variations.
tain performance. Figure 2 plots typical laser wavelength Laser based systems packaging pact, necessitating
°
vs temperature. The / C slope means that although small solution size with efficient operation to avoid exces-
temperature facilitates tuning laser wavelength, it must sive heat dissipation. Finally, the controller must operate
not vary once the laser has been peaked. Typically, tem- from a single, low voltage source and its (presumably
°
perature control of