First Light: The Story of the Laser

Lasers are such a fundamental piece of technology today that we hardly notice them. So cheap that they can be given away as toys and so versatile that they make everything from DVD players to corneal surgery a reality, lasers are one of the building blocks of the modern world. Yet lasers were once the exclusive province of physicists, laboring over expansive and expensive experimental setups that seemed more the stuff of science fiction than workhouse tool of communications and so many other fields. The laser has been wildly successful, and the story of its development is an intriguing tale of observation, perseverance, and the importance of keeping good notes.

Stimulating Developments

Like seemingly all of the major innovations in the latter half of the 20th century, the laser has a lineage that can be traced back to the leafy New Jersey campus of Bell Laboratories. But unlike some of the inventions that sprang solely from that great institution of innovation, most notably the transistor, the laser was a result of discoveries and developments from around the world over a span of decades.

Even so, the development of the laser was largely driven by the imperatives of AT&T, the parent of Bell Labs. Telephone systems in the United States and around the world were expanding rapidly through the early 20th century, and engineers were beginning to realize that simple copper wires would be inadequate to the needs of a global communications system. As the telegraph gave way to the telephone and television came on the scene, it was clear that they’d have to look for new ways to transmit vastly more information. That meant more bandwidth, and that meant using higher and higher frequencies. Looking to the future, they realized that light would be the medium someday, but a whole range of technologies would need to be invented first.

While communication with beams of light was the stretch goal, improvements in radio communications were what was achievable in the early 1950s. Again looking to the future, AT&T hoped to one day have communication satellites in orbit around the planet, acting as relay points for long-haul connections. Providing the necessary bandwidth would require microwave links, and to reach a satellite in orbit would require new designs for transmitters and receivers. A way to amplify weak microwave signals would also be needed.

Nobel Portrait of C.H. Townes. Source: Nobelprize.org

Enter Charles Hard Townes, Columbia physicist and a former Bell Labs researcher. In 1950, Townes was exploring the phenomenon of stimulated emission, the process by which incident photons can interact with atoms in an excited state, knocking them back to the ground state and releasing a new photon identical to the first photon in every way. Townes thought it would be possible to use this photonic duplicating machine to produce intense beams of microwave radiation, and had spent years building a device to prove the concept.

He called the concept microwave amplification by stimulated emission of radiation and dubbed his device a ‘maser’. It used a stream of ammonia gas pumped through a narrow slit and through an electric field into a resonating chamber. The excited ammonia atoms would be “pumped” with microwave radiation in the chamber, causing stimulated emission and massive amplification that was released as a powerful, highly focused beam of microwaves at around 24 GHz.

Townes demonstrated his maser in 1954, and Bell Labs quickly picked up on the device, building their own version in 1957 using a solid crystal rather than ammonia gas. They were also quick to pick up on the potential for the device to amplify weak microwave signals from a yet-to-be-built communications satellite. They wouldn’t have to wait long, though, as in October of that same year Sputnik flew overhead and launched humanity into the Space Age.

A Red Laser

By that point, Townes was back at Bell Labs, having been rehired as a consultant. A 1957 lunch with his Bell colleague and brother-in-law Arthur Schawlow led to a discussion about the maser and how it might be used to amplify even shorter wavelengths than the millimeter waves currently produced. Could a maser be modified to amplify light? Schawlow had already been thinking about using a maser to amplify infrared light, and Townes was intrigued by the potential of creating intense light in the visible part of the spectrum. Townes and Schawlow worked out the theoretical underpinnings of an “optical maser” and applied for a patent on the idea in 1958.

Gordon Gould in 1950. Source: American Institute of Physics

Meanwhile, across the Hudson in New York City, a young physics student named Gordon Gould was working along the same lines. Gould, fresh off a stint with the Manhattan Project that was cut short by his past ties to the Communist Political Association, was working on a doctorate in optical and microwave spectroscopy. In 1956 he had an idea to achieve stimulated emission using optical pumping rather than microwaves. He discussed his idea with none other than Charles Townes, who was still a Columbia physics professor.

Gould felt his invention was patentable, but didn’t know the ins and outs of getting a patent. Townes advised him to start writing everything down. Gould bought a cheap notebook and started writing down “Some rough calculations on the feasibility of a LASER: Light Amplification by Stimulated Emission of Radiation.”

The key to creating a laser, Gould realized, would be designing a proper optical resonator. His design included parallel mirrors of the sort used in Fabry-Pérot interferometers, devices familiar to Gould through his doctoral work. He knew that his notebook represented a substantially complete design for a working laser, and he desperately wanted to patent his invention, so he found a notary and got the notebook witnessed. Thinking this protected him, and working under the misguided assumption that he needed a working prototype to be awarded a patent, Gould dropped out of Columbia to pursue employment with a company with deep enough pockets to fund a prototype laser.

Gould had some success, joining Technical Research Group, a private research firm. He persuaded them to fund his research, which they did through a grant by the brand new Advanced Research Projects Agency (ARPA). ARPA administrators took a keen interest in Gould’s laser technology and funded it generously. Just as it seemed that Gould would be able to build his gadget and patent it, his past came back to haunt him. ARPA considered the project vital to national security and immediately classified it. This meant anyone working on the laser would need a security clearance, which Gould’s youthful Communist activities precluded. He was effectively shut out of his own project.

Ruby Rods

Theodore Maiman and his ruby laser. Source: American Institute of Physics

Hampered though they were by Gould’s absence, TRG made progress toward a visible light laser. But TRG wasn’t the only entity working on a practical laser in the late 50s, of course. Townes and Schawlow were still laboring away on open-resonator designs strikingly similar to Gould’s but arrived at independently.

In the end, both TRG and Bell Labs would be trumped in May of 1960 when Theodore Maiman, a physicist at the Hughes Aircraft Corporation in California, made the shocking announcement of a working laser. At a public press conference in July of that year, Maiman showed off his device, which used the now-familiar solid state design (in the physics sense; semiconductor lasers would come later) of a ruby rod with ends ground completely parallel and partially silvered, inside a reflector with a xenon flashlamp. When pumped by the powerful blue-white xenon arc, the ruby crystal underwent stimulated emission and released a pulse of coherent light at 694 nm wavelength, powerful enough to ignite a match, pop a balloon, or put a hole in a razor blade. The laser had arrived.

For as long as the laser took to gestate, once it was born the advances came rapidly. A continuous-mode gas laser using a mixture of helium and neon was developed later that same year. Two years later the first semiconductor IR laser was demonstrated, followed quickly by a visible light laser diode. Semiconductor laser development eventually led to the first room-temperature visible laser diode in 1970; previous laser diodes needed to be cooled with liquid nitrogen to work. The advent of semiconductor lasers and the parallel innovation of optically pure glass fibers meant that AT&T could finally realize the full potential of light communications.

Duly Noted

It’s hard to imagine the modern world without the benefit of the laser, and most of the laser’s many fathers were duly recognized. Townes won the 1964 Nobel Prize in Physics along with Russians Nikolay Basov and Alexander Prokhorov, who had been working on quantum oscillators while Townes was designing his maser.

But recognition for Gordon Gould’s role would wait almost 30 years. He filed lawsuit after lawsuit in an attempt to show that he was the rightful inventor of the laser, but again and again he was turned down. He kept trying, though, and in 1987, after having founded and run a successful fiber optic communications company, he was finally awarded a patent on the “optical pumping” aspect of lasers, based in part on the designs he sketched out in that notebook three decades earlier. Gould and the company he founded specifically to prosecute his patent war eventually took control of one major laser manufacturer and forced most of the rest to pay royalties to license his patents. But while the legal system made its opinion known as to the parentage of the laser, scientific opinion remains mixed to this day as to exactly who invented the laser.

34 thoughts on “First Light: The Story of the Laser

  1. My father machined the ruby rods for the first lasers at the Labs. They grew their own single crystal Aluminum Oxide boules and by adding .05% Chromium, made it a ruby. I still have a small piece of one of those original boules that was given to him somewhere I think.

  2. i clearly remember when there was no laser in the general public and my dad bring home one he-ne laser, it was a great fun, and when i told this to my friend he told me that i must be a liar because the laser is a weapon and it can go through the walls :) the other game that we played with it was to point it to the window across the street where my school buddy lived and he can move the little red dot on the street with a mirror, many people not even registered that they seeing something new, probably for the first time in there life, one guy wanted to buy my buddy’s mirror :) also the dogs wanted to catch the dot :) we had a great time for sure

      1. Somewhere a “super villain” will rid himself of a pesky MI-6 nuisance.

        “I too have a new toy. You are looking at an industrial laser. Which emits an extraordinary light not to be found in nature. It can prowjelt a spot on the moon. Or, at closer range, cut through solid metal. i vill show you….”

    1. Similar story here. Back in the early 80s my brother gave me a HeNe laser from a scrapped OCR equipment. I didn’t have a cat but I did take off the cloth grilles on my bedroom hifi speakers, and lightly bluetacked a tiny mirror on the cone so the light would be reflected onto the ceiling, with the laser set up on my desk. I had to run it off a conversion transformer to get the 110 volts it ran on. Even with this on just one speaker it worked great. Since the blue tack wasn’t gripping it too rigidly (didn’t want to damage the cone) it sort of wobbled a lot when there was a thumping bass, and I got crazy lissajous-like patterns that were totally awesome.

      1. Oh and I still have that laser, it’s in a heavy metal box with a cast iron baseplate. I haven’t powered it up in over 30 years, maybe 35. The mains lead has all but perished though, and I don’t know what it’s like inside. Too many other projects to work on…

  3. “… Thinking this protected him, and working under the misguided assumption that he needed a working prototype to be awarded a patent…”

    And things haven’t been right since.

  4. Actually, I thought this article was great… And obviously the focal point and other matters are at issue, but does anyone know if there is a formula, say, for the ‘wattage’ of said laser and the end point temperature of the beam ?

    Obviously ‘efficiency’ is a grand unknown here, nor am I thinking of replicating Goldfinger here… But there must be a formula that relates the output of a laser to… I don’t know (?) It’s force ? Or what would one call that ?

    In any case, am interested.

    1. Are you looking for the temperature of an object / a surface at the impact point of a laser ?

      If so, I don’t think there is a ready-to-use formula. There is too much parameters: is it a pulse ? what is the material (conductivity, specific heat) ? what is the material’s reflectivity/absorptivity ?… (I think that absorptivity is what you are refering to when you are talking about ‘efficiency’)

      But you can get an approximation by doing a balance of received power.
      With only the power comin from the laser: m*Cp*dT/dt = P_laser * absorptivity(lambda)

      And then you also need to factor in convection (if not in a vacuum), conduction, radiative dissipation,..

      1. Ok, completely understandable… Would you (or someone) be able to recommend a book or a text that goes over the basics ? I have to confess this is one area I really know ‘nothing’ about, and thus don’t know where to start, but who knows when having the knowledge might turn out to be useful in one’s tool kit.

        1. Sorry, I don’t have any book in mind. Most of what I know comes from my courses at university (and I’m still studying).
          But by looking around, I found this course from KTH (it seems to correspond to my heat transfer courses):
          http://www.energy.kth.se/courses/4A1602/2007/Lecture%20notes/heat%20transfer/HEAT%20TRANSFER4.pdf

          To sum up, you just have to write the balance of power:

          m*Cp*dT/dt = P_laser + P_rad + P_conv + P_cond + P_source

          – P_laser = P_laser_emmitted * absorpitvity(lambda)
          – P_rad = sigma*emissivity*T^4 (Stefan’s law) if your material doesn’t radiate towards any surface. Otherwise you have to add other terms (see link)
          – P_conv = h*S*(Tair-T). You can just take a standard/usual value for natural convection for h (the exchange coeficient). Or you can use empiric laws if you really need it.
          – P_cond is given by Fourier’s law. You only need the thermal conductivity.
          – P_source = 0 because you don’t have any power source (electric current / joule law for example) in the material at the impact point

          But it is yours to see which factor you can neglect, depending on the case: stationnary or unstationnary (some phenomenas are slower than others), in a vacumm or not, the type of material (conducts heat or not),…

          I hope I didn’t say anything wrong here, I’m still learning :)
          The course in the link will probably be more relialable than me (you can probably skip chapters on heat transfer and phase change). However, it might be a little bit too academic and not applied enough for your purposes

  5. It is true that the ‘story’ of ‘who invented the laser’ remains up for debate to this day, the facts of the story are all set in scientific journals and legal documents. The primary contribution to the field of quantum optics (which includes laser development) by Gordon was to hold up scientific progress by constantly suing everyone.

    Luckily, the legal system sided with the community and largely shut down his attempts, so he only managed to hold up the field for a few years before the community caught on that his attempts to cash in on ‘lasers and everything related to them’ had no legal basis. Had he been successful he could have stunted the growth of the laser industry (in the US at least) for decades.

    The similarities to the current field of 3D printing are striking. You can argue all you want about the fundamental advancements to the field and general ‘importance’ of lasers compared to 3D printing, but the fact of the matter is that the field of 3D printing also was held up for decades by one player sitting on their patents and holding a hammer next to the genitalia of anyone who dared to tread on their turf.

    Gordon’s efforts were no different–what right did Gordon have to sue everyone else working on lasers when all that he did was take the existing ideas in the field (from Einstein, Townes, Fabrey and Perot, etc) and sketch out a (fundamentally flawed, and known to be non-functional) diagram of how to combine them into a laser.

    1. Actually, his name is Gordon *Gould*.

      Although you’ve characterize Gould as lawsuit crazy, the fact that he ultimately prevailed on many of these patents indicates that he was correct and deserved to collect licensing fees.

      ———————
      A weird side-note that I recall (which could easily be wrong) regarded Bell Labs and all the laser licensing fees they’d collected for decades.

      It turns out that you can’t patent a natural phenonema, and the claim was that atmospheric conditions (perhaps on Mars) would allow for naturally occuring laser activity. So, just after Bell Labs patents were invalidated in favor of Gould, they tried to claim that no laser patents should be allowed at all.

      How convenient.

    2. So much this. Gordon Gould essentially fronted for a coalition of lawyers. They picked off small laser companies one by one. It was all about the money, honey:

      People want to believe Gordon Gould was David going up against the Townes _Schawlow Goliath but it’s just not true.. As for the verdict, read up on the proceedings and then decide if the courts always get things right. How many other contributions did Gould make? Now compare that to Townes and Schawlow.

  6. Actually von Neumann preceded them both in a private letter to Teller (published posthumously): —in a letter of September 19, 1953, to Edward Teller—producing a cascade of stimulated infrared radiation in semiconductors by exciting electrons, apparently with intense neutron-radiation bombardment. Along with his calculations, Von Neumann gave a summary of his idea:

    The essential fact still seems to be that one must maintain a thermodynamic disequilibrium for a time t1 which is very long compared to the e-folding time t2 of some autocatalytic process that can be voluntarily induced to accelerate the collapse of this disequilibrium. In our present case, the autocatalytic agent is light—in the near infrared, i.e., near 18000 Å [1.8 microns]. There may be much bet­ter physical embodiments than such a mechanism. I have not gone into questions of actual use, on which I do have ideas which would be practical, if the whole scheme made sense….

    1. And you realize how long it’s taken to get holography main stream. Even with read like with the OpenWater Company for 3D processing data for imaging similar to using non-ionizing radiation versus ionizing radiation is with tomography versus holography. Wow… finally Red Ray or whomever the company is is finally going to bring out again for a mainstream app (wasn’t there a keyboard system on the market at one time?): https://www.youtube.com/watch?v=EA3SSEWl5yM

  7. I have an ancient hobbyist’s laser. Not exactly sure how old it is, but It was built by a military technician, probably before 1980, in his spare time using plans in a magazine. The photo copies of the article have a greasy feel, like really old photo copies. I’ve never fired it up, cause it requires a lot of lab equipment, and expertise I don’t have.

      1. There it is! So according to those pages, it is a nitrogen laser, and the article is from Scientific American june 1974. I even found pictures from it. I usually use it as a conversation piece. “Oh I have a laser built on a military base” sounds like nonsense till I show it to people. lol Now I can also give a bit more context. Now I want to actually see the thing fire.

  8. In 1980 while I was in high school, my father and I built a ruby laser, pretty much from scratch, ostensibly as a science fair project. It took us almost a year to get everything juuust right so it would lase. Of course it helped that he had access to several large government laboratories and had lots of scientist friends. (He was the chief electro-mechanical engineer for the E.P.A.) It eventually broke when we overheated and cracked the crystal, but by then we were focused on creating a HeNe and/or CO2 laser (from scratch), which we never quite succeeded at. I still have the Xenon flash tube and power supply, and it makes for a hellacious strobe light!

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