Nelson, Collins, and Kaiser reply: Apart from the enjoyment of three old men looking back at their youthful efforts of 50 years ago, our purpose in writing “Bell Labs and the Ruby Laser” was to describe how our efforts came about and were carried out, so that we might bring “a modicum of peace” to the controversy that has gone on far too long. We wished to make it clear that we gave Theodore Maiman credit for the key ideas of the ruby laser—and we listed them in our article—by citing official, printed Bell Labs statements of 1960 and a later history of Bell Labs.
Jeff Hecht was initially offended by an errant phrase in our article’s first paragraph: “led to the creation of the first ruby laser.” As stated in the editorial note above, that phrase was not in our submitted manuscript, and we apologize for our poor proofreading of the editor’s reworking of it. We disavow the phrase and are pleased that Hecht is willing to put it behind all of us.
However, he still does not want to give us the credit for the first publication of attaining threshold with the accompanying pencil beam and relaxation oscillations because he does not appreciate that scientific credit is based on publication in peer-reviewed journals. Instead he wishes to base judgment on unpublished observations, personal conversations, and much delayed claims. That approach forces us to be more specific in quoting the record than we were in our search for “a modicum of peace.” In his 2000 book, 1 Maiman states in a footnote on page 150, “Before going into publication of this manuscript, I hooked up the original laser, which I still retain. Of course, as always, I used a non rod-like ‘stubby ruby’ (about 9 × 18 mm). That laser still works. It meets the Townes criteria of a red spot on the wall. It meets the Nelson specification of ‘spiking behavior.’ And, even meets the Maiman demand of effortlessly boring a hole in a Gillette razor blade!” Those claims are in sharp contrast to his 1961 report 2 that the crystals described in his two 1960 papers “exhibited R 1 line narrowing of only 4 or 5 times, a faster but smooth time decay of the output (compared to the fluorescence), an output beam angle of about 1 rad, and no clear-cut evidence of a threshold excitation.” Those two statements are in direct contradiction. Should we believe the 1961 contemporaneous statement, participated in by four coauthors and published in a respected, refereed journal, or his own claim 40 years later in his self-published book? Hecht seems to subscribe to the latter.
Hecht’s criticism that “the Bell group should have heeded [Amnon] Yariv’s report” is apparently based on the mistaken belief that everyone at Bell Labs knew what every other researcher did and said. Bell Labs had close to 20 000 employees at several different locations. Yariv was at the Holmdel location, we were at the Murray Hill lab. Our management chains were different, and joined only with the vice president of research, four levels up. None of us had ever heard of Yariv’s remarks until Hecht cited Yariv’s 2000 memoir in his letter.
Hecht repeats Maiman’s claim that in a phone call of August 1960 he told Collins he had a pencil beam. Collins is firm in his memory of no such claim by Maiman, and neither of us have any memory of Collins telling us that; it is something we would not forget.
We are pleased that Hecht has offered a figure as his “proof” of Maiman’s early observation of “spiking” (that is, relaxation oscillations) and threshold because to the eye of a scientist the figure proves the contrary of each. The undated photo with no time scale shown (probably 0.5 or 1 ms per division) purports to show spiking. But notice that the raggedness begins before the abrupt rise that shows the start of stimulated emission. Notice further that the raggedness does not stop abruptly but continues as the decay falls below the level where the stimulated emission began. The raggedness is obviously noise of some kind, not relaxation oscillations. Further, the figure shows an exponential decay, not an abrupt drop that would occur if threshold had been exceeded. To see how threshold dramatically begins and ends (a rise and fall of a factor of 1000) and how relaxation oscillations appear, see figure 1 of our 1960 letter. 3
Ralph Wuerker’s remark that Bell Labs researchers were thinking of continuous operation of a laser apparently is based on Yariv’s memoir. That doesn’t jibe with our memories. Our thinking was directed at finding a four-level system for lasing. Maiman’s most creative contribution was to believe he could adequately empty the ground state of a three-level system, like pink ruby, to make a laser.
The Myers-Dixon analysis of maser and laser patents, mentioned by William Joyce, is a fine exposition that we recommend, particularly to readers of Nick Taylor’s book. 4 And Donald Langenberg’s comments remind us that there was no dress code whatsoever for Bell Labs researchers, even for publicity shots. But dressing well in that era was regarded as a politeness to the people around us.
