Abstract:
A monolithic optoelectronic device has a spot-size converter optically connected to a waveguide. The overclad extending over the core of the waveguide is thinner and differently doped than the overclad of the spot-size converter. This structure can be made by applying a process of etching and enhanced selective area regrowth to create regions of the overclad of different thickness or doping. The spot-size converter core is made of a different material than the waveguide core by using etching and enhanced selective area regrowth.
Abstract:
A spot-size converter for coupling light between first and second waveguides respectively supporting first and second propagation modes having substantially different dimensions is provided. The spot-size converter includes a lower and an upper waveguiding structure each characterized by an effective refractive index. The lower waveguiding structure is coupled to the first waveguide to receive light therefrom or transmit light thereto in the first propagation mode. The upper waveguiding structure is coupled to the second waveguide to transmit light thereto or receive light therefrom in the second propagation mode. The upper waveguiding structure includes a plurality of longitudinally extending high-index elements arranged in multiple vertically spaced rows. At least part of the upper waveguiding structure extends at least partially over the lower waveguiding structure so as to define a coupling region wherein an effective refractive index crossing occurs, thereby enabling evanescent coupling of light between the lower and upper waveguiding structures.
Abstract:
A Mach-Zehnder optical modulator is provide and has a travelling wave electrode extending over two optical waveguide branches and modulating the relative phase of the optical beam components propagating in those branches. The travelling wave electrode has transmission line conductors and pairs of waveguide electrodes, the waveguide electrodes of each pair being coupled to one of the optical waveguide branches, respectively. The travelling wave electrode further includes active devices having a high impedance input electrically connected to one of the transmission line conductors and a low impedance output electrically connected to one of the waveguide electrodes. Each active device transfers the electrical modulation signal from the associated transmission line conductor onto the associated waveguide electrode according to a voltage transfer function.
Abstract:
A polarization-insensitive optical receiver for demodulating a phase-modulated input optical signal is provided. The optical receiver includes successively a polarization splitter, a first and second interferometric modules including respective delay lines, and a plurality of detectors. The input optical signal is split into two substantially orthogonally-polarized components, which are launched along respective optical paths into the corresponding interferometric modules where they demodulated and subsequently recombined prior to being detected by the plurality of detectors. Advantageously, the optical receiver allows mitigating undesired discrepancies between the optical paths traveled by the two polarization components by arranging the respective delay lines of the interferometric modules into intertwined spiraling structures. A waveguide assembly including a substrate and a pair of waveguides on the substrate and defining intertwined spiraling structures is also provided, as well as a waveguide coupling assembly for coupling, onto a same detector, two optical signals travelling along two parallel coplanar waveguides.
Abstract:
A polarization-insensitive optical receiver for demodulating a phase-modulated input optical signal is provided. The optical receiver includes successively a polarization splitter, a first and second interferometric modules including respective delay lines, and a plurality of detectors. The input optical signal is split into two substantially orthogonally-polarized components, which are launched along respective optical paths into the corresponding interferometric modules where they demodulated and subsequently recombined prior to being detected by the plurality of detectors. Advantageously, the optical receiver allows mitigating undesired discrepancies between the optical paths traveled by the two polarization components by arranging the respective delay lines of the interferometric modules into intertwined spiraling structures. A waveguide assembly including a substrate and a pair of waveguides on the substrate and defining intertwined spiraling structures is also provided, as well as a waveguide coupling assembly for coupling, onto a same detector, two optical signals travelling along two parallel coplanar waveguides.
Abstract:
An apodized fiber Bragg grating, and a phase mask, method and system for making such a grating are disclosed. The refractive index profile of the grating has a periodic apodization phase component which is designed so that the grating fringes reflecting light in a spectral region of interest are apodized, by generating spurious reflection features outside of this spectral region of interest. Apodization is therefore provided through a phase variation of the grating as opposed to an amplitude variation. The phase component is added to the profile of the phase mask grating corrugations to obtain the phase-apodized grating.
Abstract:
An adjustable chromatic dispersion compensator is provided, with the possibility of passive athermalisation. The device includes an optical fiber grating which is fixed on its length to an elongated beam member that has a flexible cantilever portion so that a non-uniform tensile strain induced in the grating reconfigures the group delay response. The chirp of the grating is changed by the bending of the bar, allowing adjustable chromatic dispersion compensation. Adjustment of the central filter wavelength without affecting the grating integrity is further provided. A multi-material construction allows the package to passively compensate for the natural temperature dependence of the filter resonance wavelength by varying the strain in the fiber in response to changes in the ambient temperature.
Abstract:
A fine-tuning assembly for an optical grating in an optical fiber is provided. The fiber is mounted under tension in a hollow structure which has a sliding member longitudinally slideable therein. The fiber is attached to both the sliding member and hollow structure. A slanted passage is provided in the sliding member, forming a small angle with the transversal, and a wedge member is slideably inserted in this passage. To fine-tune the spectral response of the grating, the wedge member is transversally displaced without any longitudinal displacement, preferably by the action of screws, thereby pushing on its walls to longitudinally slide the sliding member and adjust the tension in the fiber.
Abstract:
An athermally packaged optical fiber device, such as a Bragg grating, is provided. The device includes a hollow structure, and a free and a threaded member projecting in the hollow structure from both ends. The optical fiber is mounted in tension inside the hollow structure through longitudinal fiber-receiving bores in both members, and has an anchor point affixed to each member with the grating therebetween. The anchor point of the threaded member is provided outside of the hollow structure, making the device more compact. The free and threaded members are rotatable together to adjust the resonant wavelength of the grating, and a nut may be provided to allow a fine-tuning. The hollow structure, free member and threaded member have a coefficient of thermal expansion selected so that they together compensate for the temperature dependency of the Bragg wavelength.
Abstract:
A method of manufacturing a Volume Bragg Grating (VBG) is provided, comprising providing a cylindrical bulk medium made of a transparent glass material and having a central axis along a longitudinal direction, and inscribing an interference pattern in the cylindrical bulk medium. The interference pattern has a plurality of grating fringe elements distributed along a line parallel to the central axis. The method further includes rotating the cylindrical bulk medium about the central axis during said inscribing, thereby azimuthally extending the grating fringes elements. There is further provided a VBG manufactured according to such a method, the use of such a VBG in a CPA system of cladding-pumped fiber laser.