Integrated Optics: An Introduction

Laboratory work and experimental repeater work at laser wavelengths (0.4 to 10 + /Xm) has been carried out by interconnecting the oscillators, modulators, detectors, and so on, using a form of extremely short-range radio. A freely propagating beam has been reflected around corners, occasionally refocused with lenses to avoid energy loss resulting from beam spreading, and often sheltered by tubular enclosures from refractive distortions resulting from thermal gradients in the ambient air. Typical separations between components range from a few centimeters to a foot; aggregations of apparatus in a single-channel experimental laser repeater are measured 2059 2068 T H E BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 19(59 in square feet. The resulting apparatus is sensitive to ambient temperature gradients, to absolute temperature changes, to airborne acoustical effects, and to mechanical vibrations of the separately mounted parts. All of these effects are understood and are susceptible to appropriate engineering design; but one naturally looks for alternatives. Looking ahead, one sees the possibility of guiding laser beams 011 miniature transmission lines, analogous to the hollow rectangular waveguide or coaxial cable used extensively in lower frequency repeaters. Accompanying papers report contributions leading toward the new form of laser circuitry. 1-3 This paper gives a general view of the proposal and indicates specific component possibilities.