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Technology Stocks : fSONA Communications Corporation - Optical Wireless Networks -- Ignore unavailable to you. Want to Upgrade?

To: Leigh McBain who wrote (7)	3/22/2000 11:03:00 AM
From: gpowell	Read Replies (1) \| Respond to of 47

Thanks leigh. I wonder if you are at liberty to discuss the reliability of 1550nm photon propagation through rain. If so, I have a few more questions. You stated on the terabeam thread that you felt rain was not a particularly major problem for optical wireless transmission systems. Message 13251641 Yes and No, actually fog is the primary issue with optical wireless communications, rain is not a particularly major issue. My own observations indicate that 1550nm light is absorbed strongly by bulk water, as indicated by an absorption coefficient of roughly 1.3 per mm. In light of the absorption coefficient data, it seems rain would be a major issue effecting the reliability of 1550nm optical wireless communications systems. I would think that 1550nm laser light, propagating through a volume of rain, would be attenuated, scattered, and delayed. Do you any comments regarding my speculation? Could you also comment on what type of photodetectors you use. Are they InGaAs PIN diode with HEMT? - or perhaps SiGe APD? I would think that at the frequencies you are operating at (<= 1 gHz) you could have a fairly wide absorption layer, and thus maximize quantum efficiency.