| 摘要 |
A method and apparatus for transmitting an analog signal over an optical fib er cable is disclosed. A semiconductor laser provides an optical carrier signal , the laser having the natural linewidth at high power of the same order as th e SBS linewidth. The method comprises directly modulating the current of the laser with a dither signal comprising a first component fC and a second component fS. Due to the nonlinearity of the "I-V" characteristic of the laser, a thermal modulation component fT appears in the active region. This thermal modulation component reshapes the spectrum of the semiconductor lase r to increase the threshold of the SBS. As a result, the energy of the signal transmitted over the optical cable may be increased by approximately 16 dB. The first frequency is at least twice the maximum frequency of the analog signal and the second frequency is selected to obtain fC - fS = fT.
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