High-power laser using thulium-doped fiber amplifier and frequency quadrupling for blue output

摘要

An apparatus, method and associated fiber-laser architectures for high-power pulsed operation and pumping wavelength-conversion devices. Some embodiments generate blue laser light by frequency quadrupling infrared (IR) light from Tm-doped gain fiber using non-linear wavelength conversion. Some embodiments use a fiber MOPA configuration to amplify a seed signal from a semiconductor laser or ring fiber laser. Some embodiments use the frequency-quadrupled blue light for underwater communications, imaging, and/or object and anomaly detection. Some embodiments amplitude modulate the IR seed signal to encode communication data sent to or from a submarine once the modulated light has its wavelength quartered. Other embodiments transmit blue-light pulses in a scanned pattern and detect scattered light to measure distances to objects in a raster-scanned underwater volume, which in turn are used to generate a data structure representing a three-dimensional rendition of the underwater scene being imaged for viewing by a person or for other software analysis.

主权项

1. A method comprising:
providing a fiber gain medium, wherein the fiber gain medium is arranged as a ring laser; optically pumping the fiber gain medium; forcing a majority of a signal beam to travel in a first direction around the ring laser; forming a free-space version of the signal beam in the ring laser; filtering the signal beam to limit a linewidth of the signal beam in the ring laser; at a timing independently controlled by an electrical signal for each of a plurality of pulses, amplitude-modulating the signal beam to form the plurality of pulses; polarizing the signal beam to a linear polarization; extracting the signal beam as an intermediate optical signal output beam having a first wavelength between 1800 nm and 2000 nm from the free-space version of the signal beam using a polarizing beam splitter; rotating a direction of polarization on both of two sides of the polarizing beam splitter, wherein the forcing of the majority of the signal beam is done between the two rotatings of the direction of polarization; frequency quadrupling the intermediate optical signal output beam to form a frequency-quadrupled optical signal at a wavelength different from the first wavelength of the intermediate optical signal output beam; transmitting the frequency-quadrupled optical signal through water; providing an optical parametric oscillator; optically coupling the frequency-quadrupled optical signal into the optical parametric oscillator; outputting, from the optical parametric oscillator, an idler wavelength and a signal wavelength; and frequency doubling the idler wavelength and the signal wavelength to form a frequency-doubled idler wavelength and a frequency-doubled signal wavelength, wherein the transmitting of the frequency-quadrupled optical signal includes transmitting at least one of the frequency-doubled idler wavelength and the frequency-doubled signal wavelength through the water.