EXTERNAL CAVITY TUNABLE LD LIGHT SOURCE ECL-210
3-3
13-4 Precise Optical Power Control
ECL has two modes to control optical power: Automatic Power Control (APC) mode, and
Automatic Current Control mode.
3-4-1. High precise Optical Power Monitor
ECL has machinery monitoring divergently a part of light, to monitor optical output, using
optical fiber coupler of low loss and wavelength independent type. ECL does wavelength sensi-
tivity compensation, linear compensation of optical detector, cascade gain amplifier control.
3-4-2. APC Mode
In APC mode, ECL feedbacks this high precise optical power monitor signals, and controls
optical power automatically by digital PI control. When APC mode is active and wavelength
is reset, almost same optical power can be seen. Note that in a oscillation wavelength, the set
optical power may not be able to achieve, even if the injection current is driven to the current
limit.
Water molecule absorbs light in 1300nm~1500nm and the output power decreases
when measuring with optical spectrum analyzer. It is impossible to avoid it because it
is a physical phenomemon. We recommend to use ECL-210 in the condition with the
extremely low humidity or avoid the water absorption points.
APC mode
Current limit
APC working range
Optical output power
Wavelength
NOTE
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