Effects of random perturbations in plastic optical fibers

Science

Volumn 281, Issue 5379, 1998, Pages 962-967

  Garito, A F ^a   Wang, J ^a   Gao, R ^a  

^a UNIVERSITY OF PENNSYLVANIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

DATA BASE; ENERGY TRANSFER; FIBEROSCOPE; INFORMATION PROCESSING; INTERPERSONAL COMMUNICATION; PRIORITY JOURNAL; REVIEW; WAVEFORM;

EID: 0032516706     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.281.5379.962     Document Type: Review

References (19)

1. D. Marcuse, Principles of Optical Fiber Measurements (Academic Press, New York, 1981).
2. _, Bell Syst. Tech. J. 48, 3187 (1969).
3. S. Kawakami and T. Nishizawa, IEEE Trans. Microwave Theory Tech. MTT-16, 814 (1968).
4. S. D. Personick, Bell Syst. Tech. J. 50, 843 (1971).
5. D. Marcuse, ibid. 52, 817 (1973).
6. D. Gloge, ibid. 51, 1767 (1972).
7. G. Jiang, R. F. Shi, A. F. Garito, IEEE Photonics Tech. Lett. 9, 1128 (1997).
8. R. F. Shi, C. Koeppen, C. Jiang, J. Wang, A. F. Garito, Appl. Phys. Lett. 71, 3625 (1997).
9. W. A. Gambling, D. A. Payne, H. Matsumura, Electron. Lett. 9, 412 (1973).
10. See, for example, T. Okoshi, Optical Fibers (Academic Press, New York, 1982).
11. D. Marcuse, Theory of Dielectric Waveguides (Academic Press, New York, 1974).
12. Differential mode delay measurements in POFs were performed in the time domain using a temperature-stabilized InGaAlP laser diode that produced 45-ps pulses at 660 nm (peak power, 10 mW) at a repetition rate of 2 MHz. The laser diode output was collimated by a GRIN lens, spatially filtered, and then collimated by a 15-cm (focal length) lens that was focused onto the fiber end by another 15-cm lens. The focused beam spot was ∼5 μm in diameter. To excite only a small group of guided modes in the fiber, we kept the launch NA of the light beam focused into the fiber below 0.007, which is much less than the POF NA. The GI POF sample was mounted on a motorized stage, with its input end face normal to the incident beam, and translated across the beam for selective mode excitation at specified radial positions. Similarly, in the case of SI POFs, the fiber sample input end was rotated. The fiber output was detected by a sampling optical oscilloscope, and the data were stored and analyzed on a laboratory computer. The group delay for each pulse was obtained by averaging over the entire pulse.
13. 1/2. Fast Fourier transforms were carried out for accurate bandwidth measurements. The light source was a temperature-stabilized InGaAlP laser diode capable of producing 45-ps pulses at 660 nm wavelength. The repetition rate of the laser diode could be as high as 2 MHz. The laser diode output was first collimated by a GRIN lens and then spatially filtered. It was then collimated by a 15-cm lens and focused onto the POF by a micro objective lens. The output light signal was detected by a sampling optical oscilloscope. The time delay of the trigger signal for the optical oscilloscope could be adjusted by the delay box as well as by the diode controller. The main part of the optical oscilloscope consisted of a sampling streak tube to convert the light incident on the photocathode into photoelectrons. The photoelectrons were sampled and then directed to a phosphor screen, where they were converted to light. The light was then detected by a photomultiplier tube. The data stored in the oscilloscope could be fed into a computer for further data analysis. The time resolution of the system is better than 10 ps.
14. After being modulated by a chopper, the light was focused onto the input end of the fiber mounted on a rotation stage, which allowed the launch angle to be varied with respect to the fiber axis. The output end of the fiber was mounted at the center of another rotation stage. Angular scans of the far-field intensity were made using a silicon photodiode with a small active area of 1 mm, which was set on an arm that could rotate around the output fiber end. The photodiode and the fiber end were 15 cm apart, so the angular resolution was better than half a degree. The electrical signal from the photodiode was sent to a lock-in amplifier referenced by the chopper.
15. Y. Koike, T. Ishigure, E. Nihei, IEEE J. Lightwave Technol. 13, 1475 (1995). Currently, new advanced fabrication methods are under development in several laboratories worldwide.
16. L. L. Blyler, C. S. Koeppen, H. E. Bair, in POF Asia-Pacific Forum '96, 10 and 11 December 1996, Tokyo, Japan (POF Consortium, Tokyo, 1996), pp. 58-61.
17. P. E. Green Jr., IEEE J. Select. Areas Commun. 14, 764 (1996).
18. T. Kaino, in Polymers for Lightwave and Integrated Optics, L. Hornak, Ed. (Dekker, New York, 1992), pp. 1-38.
19. Supported by the Defense Advanced Research Projects Agency (grant F49620-94-1-0468), the U.S. Air Force Office of Scientific Research, and the Pittsburgh Supercomputing Center. We gratefully acknowledge the contributions of R. F. Shi and G. Jiang.