Optical wavelength monitor for passive optical components

The monitor has an optical coupler for cross-coupling signals carried by an optical waveguide using different carrier wavelengths divided into channels. The coupler is connected to a demultiplexer via an amplifier. Selected wavelengths are passed to defined outputs with detectors for converting optical signals detected in a defined channel into electrical signals. An oscillator modulates the optical signals to the amplifier with a frequency. The monitor has an optical coupler for cross-coupling at least some optical signals carried by an optical waveguide transmitted using different carrier wavelengths divided into channels, whereby the coupler is connected to a wavelength demultiplexer (4) via an optical amplifier (3). Selected wavelengths are passed to defined outputs (5) with connected detectors (6) for converting optical signals detected in a define channel into electrical signals. An oscillator (7) is provided for modulating the optical signals fed to the optical amplifier with a frequency. Independent claims are also included for a method of investigating optical signals.