|
Today's fiber optic communication systems rely on high-speed Fabry-Perot or DFB (distributed fiber Bragg) laser diodes to operate at high bandwidths from 1 Gbps to 40 Gbps. Although they are usually of the highest quality, these laser diodes always have slightly different efficiencies, and so individual lasers will never have exactly the same emitted light power, even under identical drive conditions. In addition, emitted light power will vary with ambient operating conditions (particularly temperature, as the laser will emit more light as it warms up).
In order to obtain stable ouptut, it is thus necessary in most telecom applications to monitor the emitted laser power and adjust the drive current accordingly. Without such continuous adjustment, the variation in emitted laser intensitiy will adversely affect a number of system parameters, such as transmission distance and bit error rate.
Lasers for telecom applications typically emit near-infrared light at 1310 nm, 1490 nm, and 1550 nm. InGaAs photodiodes are ideal for monitoring laser power levels at these wavelengths. Small surface-mount detectors are available for mounting within industry-standard laser packages, next to the laser die. There are also InGaAs detectors that can be fiber-coupled anywhere inside the telecommunication system.
|
|
Recommended products
|
