Nanomedicine, Volume I: Basic Capabilities
© 1999 Robert A. Freitas Jr. All Rights Reserved.
Robert A. Freitas Jr., Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999
188.8.131.52 Infrared and Optical Cables
Photon energy equals thermal noise (hnequal / kT ln(2) = 1) in the far infrared, specifically, at nequal = 6 x 1012 Hz for T = 310 K. At still higher frequencies, the cost per bit becomes the energy per photon, or hnoptical, hence the maximum transmission frequency becomes
Silica optical fibers are damaged by near-UV photons at frequencies exceeding ~1015 Hz (l ~ 300 nm), giving an upper limit on optical information transfer rates. Transmitting 1015 UV photons per second requires a power budget of Pcomm = 1 milliwatt; holding intensity to <105 watts/m2 for safety reasons (Section 184.108.40.206) mandates a fiber >100 microns in diameter. Cables this large are suitable primarily for relatively short internodal trunk lines (Section 7.3.1). At ~105 watts/m2 a 1 micron2 fiber can safely continuously transmit ~105 pW, enough to generate 1013 photons/sec at 10 THz (~1013 bits/sec), or ~10 zJ/bit. Note that below nequal, the energy cost per bit is constant; above nequal, the energy cost per bit rises linearly with frequency. Regenerative systems could in theory recover and reuse some of this energy.
Last updated on 19 February 2003