This week’s History of Fiber Optics, is from George Gilder’s book, Telecosm, if you like what you read in these articles buy it; it’s a small price for keeping up with new technology: The idea of stimulated light makes sane men dream wild dreams—of laser-based fusion energy, simulating the fires of the sun; of light punching holes in metal, cutting cloth, and gauging the distance from earth to the moon down to millimeters.
Stimulated light can work its wonders at infinitesimal powers inside microchips, or melt a mote off a retina. Bathed in the 77—degree Kelvin chill of liquid helium, a low-frequency laser device can-and-did detect the background radiation from the big bang at the birth of our universe, winning the Nobel Prize for Arno Penzias and Robert Wilson.
Lasers can perform miracles. But, to understand how all this can happen, you have to work with the quantum paradox—a feat that long defied some of the world’s greatest minds. The first scientist to harness stimulated laser energy into a working device was Charles H. Townes of Columbia University. He was a learned physicist who also worked for Bell Labs in Murray Hill, New Jersey. Townes had coauthored a definitive tome (a part of a larger body of text), on microwave spectroscopy with his Bell protégé and brother-in-law, Arthur Schlawlow. Townes was no backyard hacker and he preferred to theoretically model the full behavior of a system before trying to build a working prototype. By 1955, he was able to do that for a gas-based version of what would later be known as a laser. A decade later, he was awarded a Nobel Prize for his world changing creation.
It was not just because he’d written the book on them that Townes began with microwaves. A master, as he called it—for microwave amplification through the stimulated emission of radiation—would also be less problematic to build than a device using visible light. As Maxwell himself could’ve predicted, higher frequencies require both greater stimulating power and a smaller generating chamber. One obvious answer to that would lie in the telecommunications industry.
But this was the 1950’s and most scientists—Townes included—preferred elegant vacuum tubes and gases to their day’s still crude semi-conductors. Even after Townes had a working device, using microwaves; coherent light seemed too miraculous, and too much for physicists to swallow.
In 1956, two mid-century giants of science, Niels Bohr and John Von Neumann, visited Townes’ laboratory at Columbia University. Bohr was the reigning dean of quantum theory. Von Neumann, a very learned mathematical genius, had just laid out the architecture of the modern digital computer. The two geniuses’ told Townes that a pure beam of perfectly aligned photons was quite impossible! Coherence, Bohr and Von Neumann argued, implied regulating light waves with a precision that Heisenberg’s famed “uncertainty principle” did not allow—if the location of photons could not be predicted, they could hardly be marshaled into orderly rows, marching lockstep through space.
What the two great men either missed or failed to understand was the power of resonance, and the perfection of energy waves. For instance if two identical violins, or guitars are near one other, and a string on one instrument is plucked, the string on the instrument near it also begins to vibrate at the same frequency? Just as resonance perfectly lines up the quantum levels of atoms, resonance can line up photon waves, and make them rock spontaneously to a rising rhythm. As Townes wrote in his notes after the visit from on high, “To build a laser, we must grasp both horns of the quantum dilemma (both particle and wave paradox), at once. The emphasis on this mysterious aspect of light deflected many physicists from understanding coherent light amplification or lasers.”
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