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.

A Review of the Polarization-Nulling Technique for Monitoring Optical-Signal-to-Noise Ratio in Dynamic WDM Networks

Abstract: The polarization-nulling technique utilizes the different properties of optical signal and amplified spontaneous emission (ASE) noise for accurate monitoring of the optical-signal-to-noise ratio (OSNR) in dynamic optical networks. However, the performance of this technique is bound to be deteriorated if the signal is depolarized by polarization-mode dispersion and/or nonlinear birefringence or the ASE noise is partially polarized due to polarization-dependent loss (PDL) in the transmission link. The authors analyze these effects on the performance of the polarization-nulling technique and introduce several techniques to overcome these problems. These improved versions of the polarization-nulling techniques could monitor the OSNR with accuracy of better than plusmn1 dB, even when the differential group delay is as large as 60 ps. These techniques could also negate the effect of the signal depolarization caused by nonlinear birefringence in a highly nonlinear transmission link. The effect of the partially polarized ASE noise due to PDL is found to be not severe in most cases, as long as the PDL/span is smaller than 0.2 dB. To verify the possibility of using the polarization-nulling technique in real systems, the OSNR of the wavelength-division-multiplexed (WDM) signals transmitted through a 120-km-long aerial fiber link is measured for one week. No significant degradation in the monitoring accuracy is observed during this long-term measurement. In addition, the performance of the polarization-nulling technique in an ultralong-haul transmission link is evaluated by using a 640-km-long recirculating loop. The results show that this technique could accurately measure the OSNR in the transmission link longer than 3200 km. From these results, the authors conclude that the polarization-nulling technique is well suited for monitoring the OSNR in dynamic WDM networks

20-nm optical wavelength conversion using nondegenerate four-wave mixing

Abstract: Wavelength conversion of optical signals over 20 nm is demonstrated using highly nondegenerate four-wave mixing in a semiconductor traveling-wave optical amplifier. This technique has the potential for extremely-high-speed operation and allows continuous tuning of both input and output wavelengths over the amplifier gain bandwidth. It is demonstrated that, even for such a large wavelength conversion range, it is possible to obtain conversion efficiencies in excess of -10 dB and high extinction ratios. The feasibility of the technique is demonstrated by system measurements at 622 Mb/s, showing a 1.1-dB power penalty at 10/sup -9/ bit error rate (BER). >

Reconfigurable and scalable intergrated optic waveguide add/drop multiplexing element using micro-opto-electro-mechanical systems and methods of fabricating thereof

Abstract: Over the last several years, the rapidly increasing traffic volume carried by telecommunication networks has been clearly observed as a result of the bandwidth-intensive applications such as Internet access, electronic commerce, multimedia applications, and distributed computing. Optical telecommunication systems employing optical fibers as the transmission medium have exhibited a superior performance/cost ratio for both long-haul and short-haul routes and the emerging dense wavelength division multiplexing (DWDM)/all-optical networks have shown some promising potentials. However there still exists a need to improve speed, capacity and connectivity of optical telecommunication networks, as the information system's subscriber growth increases unrestrained. The present invention provides a reconfigurable and scalable fiber optic switching for optical telecommunication networks by integrating MEMS actuators and PLCs for optical signal switching and routing. The integrated optic waveguide switches and optical cross-connect networks are particularly applicable for DWDM/all-optical networks due to its low cost, small crosstalk, reliable, compact, reconfigurable, modular, scalable, and wavelength/polarization insensitive characteristics. The integrated optic waveguide switch can be configured into a variety of all-optical network component such as Add/Drop switch, optical cross-connect switch array, and Add/Drop DWDM filter by combining MEMS actuators and PLC networks into an integrated hybrid microsystem: Micro-Opto-Electro-Mechanical System (MOEMS).

Narrow-linewidth idler generation in fiber four-wave mixing and parametric amplification by dithering two pumps in opposition of phase

Abstract: Wide-bandwidth and high-gain fiber optical parametric amplifiers (OPAs) have been demonstrated recently. Their application as all-optical wavelength converters has been hampered by pump-induced converted-signal spectrum broadening, due to the required pump phase modulation. In this paper, we theoretically investigate and experimentally demonstrate a technique to cancel the converted-signal broadening by using four-wave mixing (FWM) or parametric amplification with two pumps phase-modulated 180/spl deg/ out of phase. The resulting converted-signal quality is comparable to that of the output signal.

Tunable add/drop optical filter

Abstract: In all-optical networks, optical switching and routing become the most important issues for interconnecting the transport network layers. This invention describes a novel tunable optical add/drop filter for the all-optical wavelength-division-multiplexing (WDM) network applications. This filter can add or drop part of the high transmission capacity signals of a WDM link. It can be used to decentralized access point in the access network or as small core network node to realizing branching points in the network topology. It works in both wavelength and space domains. It has the advantages of: 1) High throughput and low voltage operation; 2) Wide tuning range and therefore, high channel capacity; 3) High isolation and high directivity between input and output ports; 4) Compact device packaging is possible as compares to the conventional grating and mechanical switching type of add/drop filter; 5) Multiple ports add/drop tunable filters can be realized with this invention to interconnect multiple WDM networks. This novel add/drop filter can be used in various WDM topologies. It enhances the performance of the conventional tunable filter by re-routing the rejected wavelengths back to network, which not only save the precious optical energy, but also cut down the return loss of the device.