Abstract: An apparatus and a method for monitoring optical signal-to-noise ratio are provided. It can be applied in dense wavelength-division multiplexed networks to monitor the transmission quality of each optical channel. The apparatus comprises an optical circulator, a tunable optical filter, a dithering signal, a dithered reflector, and two photodiodes. It can be integrated on a single chip. The invention utilizes the dithering and reflection functions of the dithered reflector, and passes the signal and the noise through the tunable optical filter once and twice, respectively. When the tunable optical filter is scanning and filtering the whole spectrum, the signal and noise powers are measured by the two photodiodes, respectively. The OSNR for each optical channel is then calculated according to the signal and noise powers. It can monitor channel location, wavelength drift, and OSNR by including a wavelength locker to act as an optical channel analyzer.

Abstract: An apparatus and method for simultaneous channel and optical signal-to-noise ratio (OSNR) monitoring is adapted to function in multi-channel wavelength-division-multiplexed (WDM) optical communication systems. A polarization controller is sequentially adjusted to perform the sequential polarization control with an optical signal. A polarization-selective electro-optic modulator acts as a polarizer and provides a signal dithering to improve the detection sensitivity. A beam splitter splits the dithered optical signal into two clusters. A photodetector receives the first cluster and measures the OSNR. An optical element receives the second cluster and monitors the channel wavelength of multiple channels. The apparatus can be packaged into a compact module and integrated on a chip. The channel monitoring covers a wide wavelength range and is tunable. The OSNR monitoring can be accurate over a wide dynamic range.

Abstract: An apparatus and a method for monitoring optical signal-to-noise ratio are provided. It can be applied in dense wavelength-division multiplexed networks to monitor the transmission quality of each optical channel. The apparatus comprises an optical circulator, a tunable optical filter, a dithering signal, a dithered reflector, and two photodiodes. It can be integrated on a single chip. The invention utilizes the dithering and reflection functions of the dithered reflector, and passes the signal and the noise through the tunable optical filter once and twice, respectively. When the tunable optical filter is scanning and filtering the whole spectrum, the signal and noise powers are measured by the two photodiodes, respectively. The OSNR for each optical channel is then calculated according to the signal and noise powers. It can monitor channel location, wavelength drift, and OSNR by including a wavelength locker to act as an optical channel analyzer.

Abstract: An apparatus and method for simultaneous channel and optical signal-to-noise ratio (OSNR) monitoring is adapted to function in multi-channel wavelength-division-multiplexed (WDM) optical communication systems. A polarization controller is sequentially adjusted to perform the sequential polarization control with an optical signal. A polarization-selective electro-optic modulator acts as a polarizer and provides a signal dithering to improve the detection sensitivity. A beam splitter splits the dithered optical signal into two clusters. A photodetector receives the first cluster and measures the OSNR. An optical element receives the second cluster and recognizes the channel wavelength of multiple channels. The apparatus can be packaged into a compact module and integrated on a chip. The channel monitoring covers a wide wavelength range and is tunable. The OSNR monitoring can be accurate over a wide dynamic range.