No abstract

The device is fabricated as a 1 X 8 star coupler and their basic properties have been measured. The insertion loss is 10.44 dB on the average at a wavelength of 1.3 1 pni with index-matching material. Figure 2(a) shows the histogram of the excess losses of 50 devices. The excess loss is 0.54 dB on the average, which can be nearly identified with the sum of two connection losses at both ends of the device. The value is sufficiently good, suggesting that the compatilsility of the device with MT connectors has been verified. Repeatability 3f loss values has been also checked. Figure 2(b) shows the histogram of the maximum loss changes during three repetitions of connection and disconnection. The change is 0.12 dB on the average. Additionally, return losses are >40 dB for all devices. As for reliability, several kinds of ctnvironmental tests have been done. Details of the tests are summarized in Table 1. Loss deviation was monitored under the heat cycle and i emperature-humidity cycle tests. The maximum loss deviation from 25°C is less than k0.3 dB and 20.4 dB for each test respectively. Accordingly the device should be of practical use.In conclusion, we have developed a 1 X 8 star coupler waveguide device with MT-compatible connections, which is easy to fabricate because the assembling process autl2matically involves adjusting the position of waveguides. In addition to this convenience, the device has low connection losses and good relialiility. The device structure is favorable to mass production and can be applied to various waveguide circuits with low cost.