Method and apparatus for differentially controlling population inversion in gain medium

摘要

A method and apparatus are operative to control the desired level of population inversion in a gain medium having an amplified spontaneous emission (ASE) spectrum which is characterized by distinct short- and long-wavelength regions. The control is realized by the apparatus configured to determine a relationship between the regions of the ASE spectrum represented by respective frequencies which are filtered by respective frequency discriminators. The apparatus includes a controller operative to process the filtered frequencies by determining a relationship between amplitudes of the respective filtered frequencies which represents a measured level of population inversion. Upon mismatch between the measured level and desired level of the population inversion, a control signal is coupled into a pulse generator or pump or both. In response, the pulse generator may output a pulse, or/and the pump may be completely shut down to lower the level of the measured inversion.

主权项

1. A method for controlling a population inversion in an optical gain medium comprising:
pumping the optical gain medium so as to generate amplified spontaneous emission (ASE) having a power density spectrum with short-wavelength and long-wavelength regions; determining a relationship between power densities of respective short-wavelength and long-wavelength regions by measuring a ratio between amplitudes of respective desired short and long wavelengths from respective short- and long-wavelength regions or a difference therebetween, thereby measuring a level of the population inversion; generating a control signal if the measured level does not substantially match a desired level, thereby coupling the control signal to an optical component configured to alter the measured level of the population inversion so as to substantially match the desired one.