Proposal for an improved quantum-well laser amplifier with wide-wavelength operation

A concept for an improved polarization independent laser amplifier using tensile and compressively strained QWs is proposed and analyzed regarding gain and noise. The proposed structure, which utilizes QWs of several designs, has a larger wavelength operation region than the conventional approach.     

Performance of an 8×8 LiNbO3switch matrix as a gigahertz self-routing switching node

The performance of an LiNbO3 integrated-optic crossbar switch as a node in a gigahertz self-routing network is measured. Switch throughput supports 12.5 Gbit/s signals with a measured switching speed of 1.33 GHz. Crosstalk due to RF/ acousto-optic coupling and modulation depth are reported at 1.33 GHz. Optical self-routing of l00 Mbit/s information using the 8×8 switch is demonstrated.     

Polarization selective phase modulator in LiNbO3

An integrated optical phase modulator which selectively modulates only one mode of polarization is discussed. Selectivity is accomplished by controlling the ratio between the voltages applied to two different electrode sections. A method for determining the correct ratio and evaluating the polarization selectivity of the phase modulation Γ has been developed. Experimentally, a Γ of 46 dB for selective modulation in the TM direction and a corresponding value of 40 dB for the TE direction have been obtained. It is also shown that the concept is a possible alternative or complement to polarizers and polarization preserving components in optical sensors     

Tree-structured polarisation independent 4×4 switch matrix inLiNbO3

Reports on the performance of a 4×4 polarisation-independent LiNbO₃ switch matrix with a `tree-structure', permitting strictly nonblocking communicative as well as distributive switching     

Active stabilisation of polarisation on a single-mode fibre

We report on a practical method for stabilising the state of polarisation on a single-mode fibre exhibiting a 100% degree of polarisation. The principle of operation is reviewed, as are the practical implementation aspects and experimental results for polarisation stabilisation with a 1.3 ?m-wavelength laser diode.     

Integrated optics 4*4 switch matrix with digital optical switches

Reports on the first 4*4 switch matrix with digital optical switches as switch elements. The matrix is arranged in a tree structure, and comprises 24 switch elements and is pigtailed and packaged.<>     

Evaluation of an automatic method to extract the grating couplingcoefficient in different types of fabricated DFB lasers

Distributed feedback (DFB) laser parameters such as grating coupling coefficient, effective indices, facet reflectances, and the phases of facet reflectances have been determined using a method based on least-square fitting of theoretical spectra to measured, subthreshold DFB laser emission spectra. The only inputs needed are geometrical parameters such as length, grating period, and internal grating phase shifts. A larger number of devices have been successfully characterized, and consistent results have been obtained in both 1.3-μm multi-quantum-well (MQW) DFB lasers with both facets as-cleaved, and in 1.55-μm MQW DFB lasers with no, one, or two facets as-cleaved     

Optical cross-connect system in broad-band networks: system conceptand demonstrators description

A network robust to future evolution in network topologies or transmission formats and bit rates, which would be achieved by introducing an all-optical transparent layer in the transport network hierarchy is considered. The transparency would permit use of physically common fiber lines and nodes for different transmission hierarchies and/or formats. A transparent network could be achieved by combining photonic switching with electronic switching technology in the network nodes. A combination of wavelength routing and space-division switching in the optical layer would increase the capacity, as well as the flexibility in a network, allowing routing with higher granularity within the optical layer. Two optical cross-connect demonstrators have been set up. One demonstrates protection switching and restoration of traffic in a future transport network, and the other demonstrates routing of subscriber signals to different service switches in a local exchange. Space switches, tunable lasers and filters are the key technologies used to obtain enhanced flexibility     

Polarization-insensitive, monolithic 4×4 InGaAsP-InP laseramplifier gate switch matrix

Monolithically integrated 4×4 semiconductor laser amplifier gate switch arrays comprising twenty-four integrated laser amplifiers have been designed, fabricated, and evaluated. Low fiber-to-fiber loss, low polarization dependence, high extinction ratio, and low crosstalk are reported     

Pigtailed tree-structured 8×8 LiNbO3 switch matrixwith 112 digital optical switches

We report on integrated optics Ti:LiNbO₃-based 8×8 switch matrices. The matrix design uses a tree structure with 112 digital optical switches as switch elements. The matrix, which has been pigtailed and packaged in an open package for convenient system demonstrator use, exhibits a worst case insertion loss of less than 15 dB