Wavelength-division multiplexing

About: Wavelength-division multiplexing is a research topic. Over the lifetime, 25059 publications have been published within this topic receiving 332027 citations. The topic is also known as: WDM.

Communication apparatus for transmitting and receiving signals over a fiber-optic waveguide using different frequency bands of light

Abstract: Apparatus for transmitting and receiving signals over a fiber-optic waveguide using different frequency bands of light, i.e. by wavelength division multiplexing. A plurality of signal couplers interfaces modulated signals onto the waveguide in separate optical frequency bands, and a plurality of signal probes forming a probe array at one or more places in the waveguide, receives the signals, which are subject to scrambling and distortion as a result of physical irregularities in the waveguide. A recovery system coupled to the signal probes effects recovery and separation of the received signals using cumulant computations based on cumulants of the fourth or higher even order.

Optical fiber amplifiers for WDM optical networks

Abstract: In recent years, tremendous progress has been made in the development of broadband erbium-doped fiber amplifiers (EDFAs), which form the backbone of high-capacity lighwave communication systems. Initially, the use of gain equalization filters increased the bandwidth of amplifiers by a factor of three (relative to first-generation amplifiers deployed in the field). Subsequently, the introduction of a two-band architecture, which includes amplifier sections for the C-band and the L-band, resulted in a further doubling of the bandwidth. In addition, this amplifier provides high output power and low noise figure to support the ever-increasing capacity demand on lightwave systems. Commercial systems with up to 80 wavelength division multiplexing (WDM) channels having a total capacity of up to 400 Gb/s are currently available, and terabit systems have been demonstrated in the laboratory. The recently discovered phenomenon of fast power transients in chains of EDFAs constituting an optical network has been shown to impair the performance of propagating channels in the event of channel failure or network reconfiguration. Several schemes to control the gain of EDFAs have been devised to mitigate the degradation caused by the fast power transient effect. Practical broadband amplifiers incorporating these and other control schemes, such as internal attenuation to control gain tilt, will enable future terabit and higher capacity networks.

Optical performance monitoring using nonlinear detection

Abstract: A definitive goal for optical performance monitoring in an optical communications network is to provide comprehensive signal quality information in a cost-effective manner. This paper explores in detail the possibility of using nonlinear optical detection to achieve this goal. Sensitive nonlinear detection techniques commonly used in the field of ultrafast optics are applied to the problem of performance monitoring and are shown to allow quantitative measurements to be made of quantities such as accumulated chromatic dispersion, polarization-mode dispersion impairment, optical signal-to-noise ratio, and extinction ratio. Experiments performed on a 40-Gb/s transmission system demonstrate the immediate viability of this approach for measuring these quantities of interest at practical optical power levels.

Surface micromachined Fabry-Perot tunable filter

Abstract: We report the fabrication of a wavelength tunable optical filter using surface micromachining technology. The center wavelength is 1.517 /spl mu/m and the transmission bandwidth is 5 nm. The device with a 50-/spl mu/m diameter aperture has an optical loss of about 5 dB. A continuous wavelength tuning of 60 nm has been demonstrated. This device may find applications in optical sensing and wavelength division multiplexing systems, and can be readily integrated with surface emitting lasers, modulators, and detectors.

Frequency sixupler for millimeter-wave over fiber systems

Abstract: In this work, we propose and investigate a novel technique for the generation of millimeter-wave (mm-wave), i.e. frequency sixuplexing technique. The proposed technique is comprised of two cascaded Mach-Zehnder modulators (MZMs). The first MZM, biased at maximum transmission, is only used for even-order optical harmonic generation, and then a second MZM, biased at minimum transmission, is used for both optical carrier suppression modulation and data signal modulation. As an example, we consider an RF at 10 GHz, which carries the data signal and drives the MZMs; and an mm-wave signal at 60 GHz, i.e. a frequency sixupler, is obtained. It is found that our proposed sixupler leads to an 8-dB higher RF power at 60 GHz and a 6-dB improvement in receiver sensitivity with comparison to the conventional technique, i.e. optical carrier suppression modulation. The generated mm-wave signal is robust to fiber chromatic dispersion. The proposed technique is verified by experiments.