Korea Advanced Institute of Science and Technology

Keun Joo Park

Yun Chur Chung

Seung Kyun Shin

Yeun Chol Jung

Seung Gyun Shin

Jun Haeng Lee

Chun Ju Youn

Ho Chul Ji

Cheon Joo Yoon

Disclosed is an apparatus for monitoring an optical signal-to-noise ratio in a WDM optical network. The apparatus includes an orthogonal polarization component module for receiving an optical signal and outputting it after removing a signal component thereof at a specific frequency band; and calculation means for measuring both average signal and noise component intensity of the optical signal outputted from the orthogonal polarization component module. By removing a signal component at a specific frequency bandwidth and passing only a noise component through, it is possible to easily measure the noise intensity within a signal bandwidth that cannot be measured in general. A frequency band is set within a signal bandwidth, and the signal intensity is minimized at the set frequency band, so that it is possible to measure the optical signal-to-noise ratio even for a signal whose amplified spontaneous emission noise spectrum is not flat, irrespective of the signal pattern length.

Apparatus for monitoring optical signal-to-noise ratio

The present invention relates to a wavelength division multiplexed (WDM) apparatus for monitoring optical frequencies, allowing optical channel frequency monitoring using the crossover property of an arrayed-waveguide grating and pilot tones that are in wide use in optical communication networks and enhancing efficiency of operation, maintenance, and management of WDM optical communication networks. The present invention provides a WDM apparatus for monitoring optical frequencies comprising optical demultiplexing means for optically demultiplexing optical signals including externally added pilot tone signals, photo-detecting means for photo-electrically converting the output of said optical demultiplexing means, and frequency estimating means for estimating the frequency of the optical signals by measuring the amplitudes of the pilot tones from the output of said photo-detecting means.

Apparatus for monitoring optical frequencies of WDM signals

Disclosed is a multi-wavelength locking method for a wavelength division multiplexing (WDM) optical communication network, and in particular, a multi-wavelength locking method and apparatus for a WDM optical communication system that can lock wavelengths of optical signals by producing pilot tones by applying a sine-wave current to a plurality of transmission lasers having different wavelengths, passing the optical signal through a Fabry-Perot etalon filter, and then Fourier-transforming the filtered optical signal. The multi-wavelength locking method includes frequency-modulating an optical signal by applying a small and specified sine-wave current to a bias current for driving WDM lasers, detecting pilot tones produced after filtering the optical signal through a filtering section and converting the detected signal into a digital signal by performing a sampling of the detected signal, detecting a magnitude and phase of the pilot tones by performing a fast Fourier transform, providing Fourier-transformed data as a first derivative signal of the filtering section, and locking an operation wavelength of WDM channels by controlling the temperature or current if resonance frequencies of the filtering section coincide with respective standard frequency.

Multi-wavelength locking method and apparatus for wavelength division multiplexing (WDM) optical communication system

An apparatus monitoring frequency of WDM signals using pilot tone and two interleaved solid etalon filters for efficient management and maintenance of wavelength division multiplexing optical transmission network is provided. Desirably, the apparatus for optical frequency monitoring includes splitting means, a plurality of optical filtering means, optical detecting means, and frequency detecting means. The splitting means splits optical signal and the optical signal includes pilot tone. The plurality of optical filtering means filters an output of the splitting means with particular passband. The optical detecting means converts an output of the optical filtering means into electrical signal. The frequency detecting means detects an intensity of the pilot tone from an output of the optical detecting means and calculates optical frequency.

Apparatus for monitoring frequency of WDM signals using pilot tone

The optical signal-to-noise ratio (OSNR) of optical signals that are demultiplexed into a plurality of optical channels by a wavelength-division multiplexing (WDM) optical transmission system is monitored by an apparatus which outputs the optical signals of each optical channel on a first path and a second path, and measures the signal intensity of each of the optical signals on the first path. The apparatus selectively passes an AC component of each of the optical signals on the second path and processes the AC component by converting the AC component into a digital signal and performing a fast fourier transform on the digital signal. The apparatus measures the noise intensity of the processed AC component on the second path. The OSNR of each optical signal is calculated by comparing the measured signal intensity of each of the optical signals and the measured noise intensity of the processed AC component of each of the optical signals.

Growing community of inventors

Jeollanam-do, South Korea

Keun Joo Park