Method and apparatus for controlling and protecting pulsed high power fiber amplifier systems
First Claim
1. A high power fiber amplifier system comprising:
- a passively mode locked oscillator generating optical pulses at a repetition rate;
a fiber amplifier disposed downstream from said oscillator and arranged to receive at least a portion of said optical pulses from said oscillator;
a controller operatively coupled to at least said oscillator, said controller comprising an element for monitoring a repetition rate of said oscillator, said element comprising a photodetector to receive and convert a fraction of the optical power of said optical pulses from said oscillator into electrical signals representative of said repetition rate, said controller capable of determining said repetition rate from said electrical signals and calculating a required down counter divide ratio needed to obtain a desired lower repetition rate, anda reference oscillator that generates a reference signal; and
a means for synchronizing said passively mode locked oscillator with the reference signal,wherein pulses with a desired repetition rate are output from the high power amplifier system notwithstanding variations in the oscillator repetition rate as a function of time or temperature.
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Abstract
An electronic circuit for controlling a laser system consisting of a pulse source and high power fiber amplifier is disclosed. The circuit is used to control the gain of the high power fiber amplifier system so that the amplified output pulses have predetermined pulse energy as the pulse width and repetition rate of the oscillator are varied. This includes keeping the pulse energy constant when the pulse train is turned on. The circuitry is also used to control the temperature of the high power fiber amplifier pump diode such that the wavelength of the pump diode is held at the optimum absorption wavelength of the fiber amplifier as the diode current is varied. The circuitry also provides a means of protecting the high power fiber amplifier from damage due to a loss of signal from the pulse source or from a pulse-source signal of insufficient injection energy.
69 Citations
28 Claims
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1. A high power fiber amplifier system comprising:
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a passively mode locked oscillator generating optical pulses at a repetition rate; a fiber amplifier disposed downstream from said oscillator and arranged to receive at least a portion of said optical pulses from said oscillator; a controller operatively coupled to at least said oscillator, said controller comprising an element for monitoring a repetition rate of said oscillator, said element comprising a photodetector to receive and convert a fraction of the optical power of said optical pulses from said oscillator into electrical signals representative of said repetition rate, said controller capable of determining said repetition rate from said electrical signals and calculating a required down counter divide ratio needed to obtain a desired lower repetition rate, and a reference oscillator that generates a reference signal; and a means for synchronizing said passively mode locked oscillator with the reference signal, wherein pulses with a desired repetition rate are output from the high power amplifier system notwithstanding variations in the oscillator repetition rate as a function of time or temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification