Light source whose wavelength varies with temperature in order to suppress stimulated Brillouin scattering

摘要

A laser diode 68 emits signal light, the wavelength of which varies with the temperature of the diode 68. The signal light is modulated with a data signal (main signal) by a modulation unit 82 and is emitted into an optical fibre where Stimulated Brillouin Scattering (SBS) may occur. To suppress SBS a control unit 86 controls the temperature of the laser diode, varying the wavelength of the signal light in synchronization with a low frequency signal from a source 84. This expands the spectral line width of the signal light to at least 100 MHz, such that SBS in the optical fibre is suppressed. A first injection current 70 controls the wavelength of emitted signal light and a second injection current 74 controls the power of the emitted signal light, such that the wavelength can be varied while power remains constant.