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 diode pumped fiber amplifier disposed downstream from said oscillator and arranged to receive at least a portion of said optical pulses from said oscillator; and
a controller operatively coupled to at least said passively mode locked oscillator, said controller comprising an element for monitoring a repetition rate of said passively mode locked oscillator, said element comprising a photodetector to receive and convert a fraction of the optical power of said optical pulses from said passively mode locked 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 wherein said controller is arranged to dynamically control a gain of said fiber amplifier or to control the amplitude of a seed pulse so as to maintain a desired output pulse energy from said high power amplifier system.
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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.
66 Citations
34 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 diode pumped fiber amplifier disposed downstream from said oscillator and arranged to receive at least a portion of said optical pulses from said oscillator; and a controller operatively coupled to at least said passively mode locked oscillator, said controller comprising an element for monitoring a repetition rate of said passively mode locked oscillator, said element comprising a photodetector to receive and convert a fraction of the optical power of said optical pulses from said passively mode locked 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 wherein said controller is arranged to dynamically control a gain of said fiber amplifier or to control the amplitude of a seed pulse so as to maintain a desired output pulse energy from said high power amplifier system. - 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, 29, 30)
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31. A high power fiber amplifier system comprising:
a first controller operable to control an electric current of a pump diode and further control a gain of a fiber amplifier, wherein during operation of the system, an output pulse energy of the high power fiber amplifier system is controlled to be constant as a pulse width and repetition rate of amplifier system output pulses are adjusted and wherein the repetition rate is a desired down counted repetition rate of pulses injected into the fiber amplifier, wherein the desired down counted repetition rate is obtained with a down counter disposed upstream of the fiber amplifier.
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32. A high power fiber amplifier system, comprising:
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a first controller operable to control an electric current of a fiber amplifier pump diode, and further control a gain of said fiber amplifier, wherein during operation of the system, an output pulse energy is controlled to be constant as a pulse width and repetition rate of system output pulses are adjusted; and a second controller operable to control a temperature of said fiber amplifier pump diode such that a wavelength of the pump diode is maintained at a fixed value while a current of the pump diode changes. - View Dependent Claims (33, 34)
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Specification