D. W. Koon
and C. L. Jahncke,
St. Lawrence University
FOUL(UP): A Fiber-Optic Ursine Link (Universal Prototype)
We have constructed what we believe is the first prototype of a fiber-optic
link to use the hair of an Arctic mammal. The potential advantages of ursine
fiber technology over conventional technology are discussed.
Twenty years ago, fiber optic conduction of ultraviolet light by the
hairs of the polar bear (Ursus maritimus) was proposed  to explain the
large UV absorption of the animal's pelt . Subsequently, the UV absorption
of the pelt has been explained  by the absorption properties of keratin
in the hair. Also, the transmission of visible light has been shown [4,5]
to be less than 0.001% for a typical 2.5cm hair, and even less in the ultraviolet.
None of this research, however, has answered the question: can one use
polar bear hair to construct a fiber-optic telecommunications link?
We decided to answer this question by constructing the Fiber-Optic
Ursine Link (Universal Prototype) [FOUL(UP)]. The large optical losses
in polar bear hair in the infrared, visible, and ultraviolet -- over 2dB/mm
[4,5], or a loss of one-third of the signal every millimeter -- restricted
the practical length of our FOUL(UP) fiber to less than an inch in length,
greatly simplifying device design, since we didn't need to splice individual
Figure 1: Actual experimental setup. The laser is directly above the
center of the photograph. Microscope objective, ursine fiber-optic link,
and silicon-diode sensor are directly below the center. The laser power
supply is to the left.
The apparatus, shown in Figure 1, was mounted on an optical table. Polar
bear hairs were obtained from John Foster at the Seneca Park Zoo in Rochester,
NY and from Angler's Choice Fly Shop of St. John, NB. We used aluminum
foil both to mount a single 4mm-long hair and to optically isolate its
two ends from each other. A 3mW diode-laser beam of about 650nm was
focused onto one end of the hair, using a microscope objective, and the
laser was modulated at frequencies from 10Hz to 102kHz, simulating a signal
sent over a fiber-optic link. A silicon-diode detector was positioned near
the opposite end of the hair to detect the transmitted signal. The detector
was connected to a filter and oscilloscope to display the waveform, which
is shown in Fig. 2 for a 102kHz signal. The hair's optical throughput was
a constant 3% for frequencies from 10Hz to 102kHz, the highest frequency
we could obtain from our oscillator.
Figure 2: Filtered output of the sensor for a laser signal modulated
The oscilloscope trace in Figure 2 shows the signal transmitted through
our optical fiber link, demonstrating the feasability of FOUL(UP) technology
over short distances. The low 3% throughput of this link, and the fact
that this throughput decreases by a factor of 100000 for each additional
inch of hair length, means that polar bear photonics lags far behind glass-based
fiber optic technology in performance. Still, there might be niches in
the telecommunications industry for which FOUL(UP) fibers would outperform
glass. (See Table I) In particular, the often-touted ubiquity of sand,
a raw material for making glass, is a moot point in the Arctic, where any
sand is often buried under heavy layers of snow and ice. In the Arctic
region, the raw material for FOUL(UP) fibers is, however, relatively plentiful.
Furthermore, polar bear hair is a more quickly renewable resource than
is sand. On the other hand, the high optical loss in polar bear hair perhaps
ensures that FOUL(UP) technology may never be suited for anything but short-distance
telephony . Still, the restriction to short distances is likely to allow
for ultra-low dispersion, a goal of many researchers currently enamored
of glass-based fiber technology.
Table I. Relative advantages and disadvantages of glass and
ursine fiber-optic technology:
* Except in Arctic region
** Less than about an inch
||Much more plentiful in Arctic region
||Mature, economical technology
||Simpler, inexpensive technology
||Low loss: suitable for long-distance telephony
||High loss: suitable for short-distance** telephony
||Dispersion limits available bandwidth
||No noticeable dispersion over length tested
In summary, we have demonstrated the possibility, if not feasibility,
of using the hair of a polar bear for telephony by constructing a fiber-optic
ursine link (universal prototype) [FOUL(UP)]. We are still trying to explain
to our family, friends, and colleagues why we have done so. Clearly more
work needs to be done.
1. Grojean, R. E., Sousa, J. A., Henry, M. C., "Utilization of solar
radiation by polar animals: an optical model for pelts", Applied Optics
19 (3), 339 (1980).
2. Lavigne, D. M and Øritsland, N. A., "Black Polar Bears",
Nature 251, 218 (1974).
3. Bohren, Craig F. and Sardie, Joseph M., "Utilization of solar radiation
by polar animals: an optical model for pelts; an alternative explanation",
Applied Optics 20 (11), 1894-6 (1981).
4. Koon, Daniel W., "Is polar bear hair fiber optic?", Applied Optics,
37 (15), 3198-0 (1998).
5. Hutchins, Reid, "Examining the optical properties of the polar bear
pelt", unpublished senior thesis, St. Lawrence University Physics Dept.
6. Less than about an inch.
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