A 1.3 µm edge-emitting LED is used to launch an average optical power of 13.7 dBm into single-mode fibers. This permits analog video signal transmission over a distance of 42 km with a loss margin of 5 dB. No degradations of DG, DP, and signal-to-noise ratio have been observed.

To construct a Fiber-To-The-Home network, high count optical fiber cables are needed. The requirements for these cables are small diameter, light weight, and high capacity. We studied the cable structures for ribbon fiber, which are useful for quick splicing. We calculated the diameter of three types of cables: a slotted rod cable, a loose tube cable and a newly developed U-groove cable. When the same ribbons are cabled with the same clearance, the cross sectional area of the U-groove cablet is about 27% less than that of the other two cables. No problems with the manufactured 1500-fiber U-groove unit cable are detected by the conventional cable testing.

High density and small diameter optical fiber cables are required in order to construct "Fiber To The Home (FTTH)" to support multi media services economically. By reducing the cable diameter and weight, it will be possible to install longer lengths of cable and use conduits more effectively. Moreover, the development of low loss multifiber connectors and joint boxes will reduce the joining time. It is expected that the achievement of the above will lead to reductions in installation and joining costs. This paper describes the design and performance of 1000-fiber single slotted core cable. Its diameter is 30 mm compared to 40 mm for currently used multi slotted core cable, and its weight is 0.85 kg/m compared to 1.4 kg/m. The reduced cable outer diameter and weight allow us to increase both the installed length from 1 to 2 km (pre-connectorized) and the maximum fiber count from 1000 to 1600 for multiple installation in a conduit. We also describe low loss 4, and 8 mechanically transferable (MT) connectors, a pulling head and a joint box. The average connection loss of those connectors is reduced from 0.35 to 0.2 dB. The cable joining time was greatly reduced from 9 to 4.5 hours by using 5 stacks of multi fiber connectors and newly developed pulling heads and a joint boxes. Finally, we describe field test results for 1000-fiber pre-connectorized cable. In field tests, this preconnectorized cable is sufficiently stable with present installation methods. These results will lead to reductions in installation and joining costs. The 1000-fiber pre-connectorized single slotted core cable is promising with regard to upgrading the access network towards FTTH.

Buried heterostructure waveguides with high coupling efficiency for dual shaped core fiber with zero dispersion at 1.55 µm are described. Calculations reveal that the mode mismatch loss of 0.35 dB with mode confinement coefficient of 0.6 can been achieved for dual shaped core single-mode fibers. While, for conventional single-mode fibers, mode mismatch loss becomes large.

Far-end measurement instrument for baseband frequency response, based on swept frequency method, is designed and constructed. In constituting the measurement instrument, it is important to stabilize modulation frequency characteristics of laser diode which is significantly affected by externally reflected light to the laser diode. It has been found that by coupling laser diode to a fiber with obliquely polished end face, the influence of externally reflected light can be negligibly small. Optimum coupling conditions, concerning tilt angle of fiber end and distance between fiber and laser facet are clarified. Moreover, automatic power control and temperature control circuit has been applied to the above laser to fiber coupler and far-end measurement instrument of baseband frequency response has been constructed. As a result, sufficient stabilization of modulation frequency characteristics to measure baseband frequency response of graded-index optical fiber has been attained.

Simple formula has been proposed to estimate baseband bandwidth of an optical transmission line made of different fibers spliced together. Using the formula, cumulative bandwidth is predicted merely from the bandwidth for each individual fiber. The usefulness of the formula has been confirmed by experiments.

A design principle of total reflection type optical switches with broad wavelength bandwidth using the plasma dispersion effect in GaAs is described. Wavelength dependent excess loss due to Goos-Hanchen shift in wavelength region from 1.3µm to 1.55 µm is reduced to within 0.1 dB with waveguide cross angle of 5 and injected current density of 16 kA/cm2.