Apparatus and Method For Optical Time Domain Reflectometry

An optical signal routing device comprising:

• a lens positioned for receiving an optical signal;
• a wavelength division multiplexer (“WDM”) filter;
• and
• a reflector, the WDM filter positioned between the lens and the reflector, the WDM filter configured to pass a signal of a first wavelength attenuated by at most a first attenuation, and to pass a signal of a second wavelength attenuated by at least a second attenuation, wherein the second attenuation exceeds the first attenuation by at least a first predetermined amount,
• wherein the reflector is configured to reflect the signal of the first wavelength toward the WDM filter with an attenuation of not more than a third attenuation, wherein the second attenuation exceeds the third attenuation by at least a second predetermined amount.

An optical signal routing device comprising:

• a first lens positioned for receiving an optical signal;
• a second lens;
• a wavelength division multiplexer (“WDM”) filter positioned between the first and second lenses, the WDM filter configured to pass, to the second lens, a signal of a first wavelength attenuated by at most a first attenuation and a signal of a second wavelength attenuated by at least a second attenuation, wherein the second attenuation exceeds the first attenuation by a first predetermined amount;
• and
• a reflector positioned to reflect the signal of the first wavelength, passed by the WDM filter to the second lens, toward the WDM filter with not more than a third attenuation, wherein the second attenuation exceeds the third attenuation by a second predetermined amount.