| 摘要 |
For a laser transmitter (12) used in an optical communication system, automatic compensation is provided to maintain constant (CNR carrier/noise ratio) (30, 32) and OMI (optical modulation index) regardless of changes in direct current through the laser transmitter (12) caused e.g. by temperature, aging effects, or operator power adjustments. In accordance with the invention this is compensated for by providing a control loop (14, 16, 20, 22) which senses any increase in laser DC supply current and increases the modulating current to the laser (12) as required to keep CNR constant.
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