COUPLING OF QUASI-CONTINUOUS WAVE (QUASI-CW) DIODE

QUASI-CONTINUOUS WAVE DIODE LASERS (ARRAYS) ARE THE MOST POWERFUL AND LEAST EXPENSIVE FORM OF LIGHT OBTAINABLE FROM SEMICONDUCTORS. UNFORTUNATELY THE OUTPUT BEAM SPATIAL PROPERTIES ARE POOR, AND THE HIGHLY RECTANGULAR, RELATIVELY INCOHERENT RADIATION PATTERN IS DIFFICULT TO USE. IN CONTRAST, THE UNIFORM, CIRCULAR OUTPUT EMISSION OF AN OPTICAL FIBER IS A VERY USEFUL FORM OF RADIATION. IF DIODE ARRAYS COULD BE EFFICIENTLY COUPLED INTO AN OPTICAL FIBER, THEY WOULD GAIN A MUCH WIDER ACCEPTANCE. THIS PROPOSAL ADDRESSES A NEW IDEA WHICH IS CAPABLE OF COUPLING ONE OR MORE QUASI-CW ARRAYS TO A SINGLE FIBER WITH VERY HIGH SPECIFIC BRIGHTNESS. THIS TECHNIQUE IS POTENTIALLY SIMPLE, ROBUST AND HIGHLY EFFICIENT. THE THEORETICAL BRIGHTNESS THROUGH THE FIBER CAN BE VIRTUALLY AS BRIGHT AS THE DIODE EMITTER STRIPE ITSELF. WE ANTICIPATE THIS COUPLING WILL ALLOW A 5-ARRAY STACK TO PRODUCE 350 W (200 MICROSECOND PULSE) OF LIGHT THROUGH A SINGLE 900 MICRON FIBER, WITH A NUMERICAL APERTURE OF .18. ANTICIPATED BENEFITS: THIS TECHNIQUE PROVIDES AN OPTIMAL SOLUTION FOR THE COUPLING PROBLEM AND WILL EXPAND THE UTILITY OF QUASI-CW ARRAYS. APPLICATIONS INCLUDE SOLID STATE LASER END-PUMPING FOR HIGH ENERGY, HIGH BEAM QUALITY DIODE-PUMPED SYSTEMS, IN ADDITION TO PRECISION MACHINING, LASER RANGING, AND FLASH INFRARED ILLUMINATION.