In the early 90's I got to know Dr. Kao through volleyball - his daughter was a teammate. I was working in Optical Communications at Bell Labs Area 11, but didn't realize he was "THAT C. Kao" ! A great guy in general and here's a little insight into him: A group of us were going to move him from an apartment in mid-Manhattan to a house in NJ, and we were doing a walk-through to size up the work necessary. I saw a large (6') framed scroll hanging on the wall; lovely hand-brushed calligraphy. Dr. Kao asked "Would you like me to translate?". It had been presented to him by the CUHK Dept. of Electronics on his retirement. With a slight grin he said "This is what it SAYS" and marked each character with his finger: "You .. see .. greatness .. in .. the .. smallest .. of .. things". But then with a devilish grin he remarked "But this is what it MEANS" and jabbing with the finger: " YOU .. MAKE .. LOTS .. OF .. TROUBLE .. OVER .. NOTHING !". It being Fathers Day he took us all out to a very nice restaurant for dim sum. In my book, that's a Mensch.
I don't believe the way in which you characterize the glass clarity improvement (10^98) is correct and it exaggerates the extent of the improvement that took place. Given that light attenuates exponentially with distance, the calculation you've done is sensitive to the distance used (1 kilometer) rather than being unitless. For instance, if a distance of 500m was used instead, the losses would be 10 dB and 500 dB, respectively and you'd report an improvement of 10^49. The relevant unitless value to report as the improvement is the ratio of these decibel improvements (i.e. both 1000/20 and 500/10 are a 50x improvement). This is the required decrease in defects per unit length of the fiber optic to produce these results.
Of course, a 50x improvement is impressive, but in line with the type of improvements of Moore's law, rather than fiber optics being a novel case of a 10^98 improvement factor.
Having heard about dark fiber in the early 2000s, something I’ve been wondering is: what is the current level of utilization of all that (once-?) dark fiber? Or has there been further improvements in fiber technology that would make the old fiber obsolete?
I have heard (but not verified) that at this point, fiber is as good as it needs to be for a long time. The real bottleneck these days is the optics which transmit the data. They're the throttle on how fast networking can go. I dunno if that's true of that "dark fiber", maybe that stuff really is obsolete.
Thanks . Nice article . What do you think comes next in this space ? For instance , I see a company has recently completed manufacturing of ZBLAN in space. I don’t know the details enough to make an assessment .
In the early 90's I got to know Dr. Kao through volleyball - his daughter was a teammate. I was working in Optical Communications at Bell Labs Area 11, but didn't realize he was "THAT C. Kao" ! A great guy in general and here's a little insight into him: A group of us were going to move him from an apartment in mid-Manhattan to a house in NJ, and we were doing a walk-through to size up the work necessary. I saw a large (6') framed scroll hanging on the wall; lovely hand-brushed calligraphy. Dr. Kao asked "Would you like me to translate?". It had been presented to him by the CUHK Dept. of Electronics on his retirement. With a slight grin he said "This is what it SAYS" and marked each character with his finger: "You .. see .. greatness .. in .. the .. smallest .. of .. things". But then with a devilish grin he remarked "But this is what it MEANS" and jabbing with the finger: " YOU .. MAKE .. LOTS .. OF .. TROUBLE .. OVER .. NOTHING !". It being Fathers Day he took us all out to a very nice restaurant for dim sum. In my book, that's a Mensch.
I don't believe the way in which you characterize the glass clarity improvement (10^98) is correct and it exaggerates the extent of the improvement that took place. Given that light attenuates exponentially with distance, the calculation you've done is sensitive to the distance used (1 kilometer) rather than being unitless. For instance, if a distance of 500m was used instead, the losses would be 10 dB and 500 dB, respectively and you'd report an improvement of 10^49. The relevant unitless value to report as the improvement is the ratio of these decibel improvements (i.e. both 1000/20 and 500/10 are a 50x improvement). This is the required decrease in defects per unit length of the fiber optic to produce these results.
Of course, a 50x improvement is impressive, but in line with the type of improvements of Moore's law, rather than fiber optics being a novel case of a 10^98 improvement factor.
This is a good point, thanks, I've corrected this.
OK, that exceeded my expectations. Beautiful level of detail, and all written with great clarity. Fascinating. A lot I didn’t know. Thank you.
Excellent clear explanation. Even lay people will grasp this
A minor point: the physicist credited with inventing the laser is Theodore Maiman, not Thomas.
Having heard about dark fiber in the early 2000s, something I’ve been wondering is: what is the current level of utilization of all that (once-?) dark fiber? Or has there been further improvements in fiber technology that would make the old fiber obsolete?
I have heard (but not verified) that at this point, fiber is as good as it needs to be for a long time. The real bottleneck these days is the optics which transmit the data. They're the throttle on how fast networking can go. I dunno if that's true of that "dark fiber", maybe that stuff really is obsolete.
https://www.laserfocusworld.com/industrial-laser-solutions/article/14219279/laser-industry-pioneer-elias-snitzer-passes-away
I use fiber optics everyday in our scopes in GI. J had no idea how they worked. This was a great read! Thank you!
Brilliant article.
Most interesting and useful.
Great story. Thank you!
Thanks . Nice article . What do you think comes next in this space ? For instance , I see a company has recently completed manufacturing of ZBLAN in space. I don’t know the details enough to make an assessment .
Fantastic article about fiber optics.