Wavelength Conversion Technique Research Articles

Wavelength Conversion in WDM All-Optical Networks and Analytical Models

This paper gives a brief introduction to the various wavelength conversion techniques. In order to explain the applications and benefits of the wavelength conversion techniques in WDM all-optical networks, several analytical models are studied.

Polarization independent, all-fiber phase conjugation incorporating inline fiber DFB lasers

We propose and demonstrate a novel technique for optical wavelength conversion and phase conjugation by fiber four-wave mixing using inline fiber distributed-feedback lasers as orthogonally polarized pump sources. This technique features polarization independent operation and a simple all-fiber configuration without the need for externally injected pumps. Polarization dependency as low as 0.5 dB has been achieved using this technique.

Tunability of polarization-insensitive wavelength converters based on four-wave mixing in semiconductor optical amplifiers

Optically transparent wavelength converters, in which the output is a wavelength-converted replica of the input, may be required to improve performance and ease management in future mixed-mode wavelength division multiplexed networks. Four-wave mixing (FWM) in semiconductor optical amplifiers (SOA's) is an attractive optically transparent wavelength conversion technique because it allows pump tunability. So far, three schemes for polarization-insensitive FWM in SOA's have been demonstrated, using two copolarized pumps, two orthogonal pumps, and polarization diversity. This paper presents a comparison of their output signal-to-noise ratio, and hence their ultimate tunability. A simple analytical model for FWM in SOA's is used to predict that when each scheme has the same inputs and produces the same frequency shift, the polarization-diversity scheme has the highest output signal-to-noise ratio of the three schemes, and hence promises the greatest tunability.

Virtual wavelength path cross-connect based on optoelectronic wavelength conversion

This paper describes the system design and performance of a virtual wavelength path cross-connect (VWP-XC); we demonstrate its function of wavelength conversion, cross-connection, and transportation. We realize a feasible wavelength conversion technique using an optical receiver and a tunable DBR laser. Frequency stability of a 100 GHz-spaced wavelength-converted signal is confirmed by a multiwavelength simultaneous monitoring circuit (MSMC) to be within 100 MHz. VWP cross-connection and error free transportation over 160 km and four 120 km spans (480 km with 3 repeaters) is confirmed in a five-node VWP network.

All-optical wavelength converter scheme for high speed RZ signal formats

The authors demonstrate an all-optical wavelength conversion technique that overcomes the carrier recovery time constraints of SOAs, enabling RZ output signals. Penalty-free conversion at 40 Gbit/s over 30 nm, with a monolithically integrated Mach-Zehnder interferometer is demonstrated for the first time.

Wavelength conversion technologies for WDM network applications

WDM networks make a very effective utilization of the fiber bandwidth and offer flexible interconnections based on wavelength routing. In high capacity, dynamic WDM networks, blocking due to wavelength contention can he reduced by wavelength conversion. Wavelength conversion addresses a number of key issues in WDM networks including transparency, interoperability, and network capacity. Strictly transparent networks offer seamless interconnections with full reconfigurability and interoperability. Wavelength conversion may be the first obstacle in realizing a transparent WDM network. Among numerous wavelength conversion techniques reported to date, only a few techniques offer strict transparency. Optoelectronic conversion (O/E-E/O) techniques achieve limited transparency, yet their mature technologies allow deployment in the near future. The majority of all-optical wavelength conversion techniques also offer limited transparency but they have a potential advantage over the optoelectronic counterpart in realizing lower packaging costs and crosstalk when multiple wavelength array configurations are considered. Wavelength conversion by difference-frequency generation offers a full range of transparency while adding no excess noise to the signal. Recent experiments showed promising results including a spectral inversion and a 90 nm conversion bandwidth. This paper reviews various wavelength conversion techniques, discusses the advantages and shortcomings of each technique, and addresses their implications for transparent networks.

Quantum Engineering of Optical Nonlinearities

Second-order optical nonlinearities in materials are of paramount importance for optical wavelength conversion techniques, which are the basis of new high-resolution spectroscopic tools. Semiconductor technology now makes it possible to design and fabricate artificially asymmetric quantum structures in which optical nonlinearities can be calculated and optimized from first principles. Extremely large second-order susceptibilities can be obtained in these asymmetric quantum wells. Moreover, properties such as double resonance enhancement or electric field control will open the way to new devices, such as fully solid-state optical parametric oscillators.

Polarisation-independent wavelength conversion using nonlinear optical loop mirror

A polarisation-independent all-optical wavelength conversion technique is proposed that uses a nonlinear optical loop mirror (NOLM). When the polarisation state of the input signal light is varied, wavelength-converted signals exhibit a converted power fluctuation of only 0.6 dB, and the receiver sensitivity does not change.

Wavelength conversion for frequency-modulated light using optical modulation to oscillation frequency of a DFB laser diode

A technique for wavelength conversion for frequency-modulated (FM) light is described. It utilizes the light-injection-induced frequency shift of a distributed-feedback (DFB) laser diode and the frequency-modulated-to-intensity-modulated (FM-IM) conversion function of the Mach-Zehnder (M-Z) optical filter. Input FM light is converted into IM light by the M-Z filter. The IM light is injected into the DFB-LD oscillating at another wavelength, modulating its oscillation frequency. The output from the DFB-LD has an FM signal identical to the input FM light. Thus, wavelength conversion for FM light is achieved. The characteristics of the frequency shift induced by this optical injection were experimentally studied using a lambda /4 phase-shift DFB-LD. A wavelength conversion experiment was performed. In the experimental demonstration, FM light at 1.534 mu m was converted into FM light at 1.550 mu m.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>