Abstract: In some implementations, a device may apply a modulation to an electrical current to derive a modulated electrical current. The device may supply the modulated electrical current to an optical pump source for an optical amplifier to cause the optical pump source to emit light based on the modulated electrical current. The device may generate a signal based on an optical power of the light emitted by the optical pump source. The device may filter the signal with respect to a feedback signal that is to result from the modulated electrical current to derive a filtered signal. The device may process the filtered signal to identify whether the feedback signal is present in the filtered signal based on a power indicated by the filtered signal. Whether the feedback signal is present indicates a state of the optical pump source.

Abstract: A gravity controlled lubrication system for aircraft engines to supply a lubricant from a tank to a circulating system permitting lubricant to flow when the aircraft changes to an inverted flight condition.