optical circulator as a bidirectional one fiber solution

[lists.nanog at monmotha.net (Brandon Martin)]

On 08/13/2018 06:24 PM, Ben Cannon wrote:
> What about 100Ghz ITU spacing on the tx, are the rx optics broad enough 
> to take the off-band input?

Non-coherent receivers usually seem to even when paired with DWDM grid 
transceivers.  You're paying for the tightly controlled laser on those, 
not so much the receiver.

Coherent of course will demod whatever you tune them to (and pretty well 
reject other stuff) but are therefore subject to their LO tuning range.

Figure your typical OOK optical receiver is roughly like a single-stage 
AM radio receiver (crystal radio or similar, just followed by 
amplification to logic level) without any front-end filtering on it. 
The demux in front of it, where present, is the front-end filter.  It'll 
capture and downconvert to RF basically anything it sees.
-- 
Brandon Martin