Optical analog CATV system conveying 100 channels in a 1.5-GHz subcarrier with the use of the AM-VSB format

✍ Scribed by Maria Cristina Ribeiro Carvalho; Luiz Fernando M. Conrado; Marbey M. Mosso; Abelardo Podcameni

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 833 KB
• Volume: 11
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/(sici)1098-2760(199603)11:4<215::aid-mop15>3.0.co;2-a

✦ Synopsis

I Testingchamber I ,Optical fiber pigtail LD 1 . 3 Interferometer gas sensor Figure 4 Schematic diagram of gas-exposure apparatus. The testing chamber has a volume of 5.25 dm3

TABLE 1 Experimental Results Sensing Reaction Rate of Output NO, Volume Time Intensity Change 3 r d 4 minutes -2.6% 5ml 7 minutes -3.0% 8 ml 10 minutes -3.4% 10 ml 12.7 minutes -11% 15 ml 13.5 minutes -9.0% Restoration Time 3 minutes 6 minutes 7.5 minutes 8 minutes 7.2 minutes output power reduction was stopped. Therefore, we can ob-

tain the rate of output intensity change, that is, (P, -P , ) / P , .

The experimental results are shown in Table 1.

Conclusions

We have demonstrated a new integrated optical interometer gas sensor. Metalloporphyrin with a gas-sensing function was synthesized, and then deposited onto the substrate surface of the sensing device for experiments with test gas NO,.

With increasing NO, volume, the gas-sensing reactions with the active LB film and the restoration of the active film, take longer and the phase shift of the active arm of interferometer increases. This results in a greater change of the optical output intcnsity. The volume of 3 ml should be a sensing minimum from which we can decide the sensitivity of a sensor. Also, the volume of 10 ml should be a sensing maximum, because saturation occurs when the test-gas volume is over 10 ml.