FREQUENCY QUADRUPLED LASER USING THULIUM-DOPED FIBER AMPLIFIER AND METHOD

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. An apparatus comprising:
an infrared laser outputting a laser signal having a first wavelength between 1800 nm and 2000 nm as an intermediate optical signal output beam; a frequency quadrupler operably coupled to receive the intermediate optical signal output beam and to output a frequency-quadrupled optical signal; a beam polarizer configured to orient a polarization direction of the frequency-quadrupled optical signal in a direction that enhances transmission through an air-water interface; a beam transmitter operably coupled to transmit the polarized frequency-quadrupled optical signal through water; a light detector and processor configured to detect and process reflections from the transmitted frequency-quadrupled optical signal to generate image data, wherein the light detector includes a narrowband light filter configured to increase a signal-to-noise ratio of the detected reflections.