| 摘要 |
In a technique for the automatic frequency control of semiconductor lasers, a signal emitted from the laser is sent to an optical resonator whose resonance frequency is modulated by a ramp signal, and the signal from the resonator is converted into an electrical signal. The derivative of the electrical signal is calculated, the zero crossing of the derivative is detected, and the ramp signal is sampled in correspondence with such a zero crossing. The sample thus obtained is algebraically summed with a reference signal dependent on the nominal laser emission frequency, to obtain an error signal which is used to control a driver for the laser. In the case of a plurality of lasers whose signals are wavelength multiplexed, the ramp signal is sampled in correspondence with the derivative zero crossings corresponding to the emission frequencies of the individual lasers, and the samples thus obtained are compared with respective reference signals to obtain a control signal for each laser. |
