A phase measurable optical heterodyne interferometer which is capable for measuring both the modulus r₁₂(0) and the phase ψ₁₂(0)arg{r₁₂(0)} of the spatial coherence function r₁₂(0) without the need of the optically stringent requirement for the equality of the path-lengths in the two arms of the interferometer is established. An extended formulation for the intensity correlation function of optical fields is also presented in relation to the theory of the interferometer. The experimental verifications are presented and are compared with the results obtained from other interferometric systems.

This paper reports a new operational mode, Group Transit Switching (GTS)" applicable to transit switching centers in a switched communication network. Group Transit Switching (GTS) proposed here is a kind of transit switching where a multiple number of trunk circuits is assigned to a route and reset in proper time as a group. In this approach, cascaded trunk circuit groups are kept connected for a period of time between specific two switching centers via so-called group transit switching center(s), where the number of trunk circuit groups being increased or decreased according to the change of traffic flow pattern on group basis. Thus, it is possible to save control load of the transit switching centers and to improve the adaptability of the communication network to traffic pattern variation. This paper also reports quantitative investigation on the traffic characteristics of GTS and the switching control load of group transit switching center, as well as some GTS application field. It is indicated that this GTS system can realize a saving of transit switching center switching control load and the flexible operation of the communication network without sacrificing the trunk efficiency of corresponding trunk circuit too much.

Estimations on power-delay product as a figure of merit of transferred-electron devices are made for GaAs, InP and Ga_0.5In_0.5Sb, from a digital device point of view, taking account of the temperature rise. It is shown by comparison of these figures of merit that Ga_0.5In_0.5Sb is the most promising material for a high speed digital device.