Meeting the increasing demand for capacity in wireless networks requires the harnessing of higher regions in the radiofrequency spectrum, reducing cell size, as well as more compact, agile and power-efficient base stations that are capable of smoothly interfacing the radio and fibre segments. Fully functional microwave photonic chips are promising candidates in attempts to meet these goals. In recent years, many integrated microwave photonic chips have been reported in different technologies. To the best of our knowledge, none has monolithically integrated all the main active and passive optoelectronic components. Here, we report the first demonstration of a tunable microwave photonics filter that is monolithically integrated into an indium phosphide chip. The reconfigurable radiofrequency photonic filter includes all the necessary elements (for example, lasers, modulators and photodetectors), and its response can be tuned by means of control electric currents. This is an important step in demonstrating the feasibility of integrated and programmable microwave photonic processors. A tunable photonic microwave filter is monolithically integrated in an InP chip. The filter includes all of the required elements — a laser, a modulator and a photodetector — and its response can be tuned by controlling the electric currents.

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A monolithic integrated photonic microwave filter

A single-section, compact, passive polarization converter has been designed and fabricated on GaAs-AlGaAs. The device uses an optimized waveguide structure with angled-facets to obtain 90/spl deg/-polarization rotation in a single section; this waveguide structure eliminates the need for longitudinal variation and hence avoids any section-to-section coupling losses. A transverse electric (TE) to transverse magnetic (TM) polarization conversion of 96% is achieved for a conversion length of /spl ap/720 /spl mu/m.

Realization of a compact and single-mode optical passive polarization converter

A simple and general set of design rules for slanted-angle polarization-rotating waveguides is presented in this paper. These design rules are employed to construct single-mode SOI polarization rotators that offer significant advantages in conversion efficiency, optical loss, fabrication tolerance, spectral response and spatial dimensions relative to III-V components.

Design rules for slanted-angle polarization rotators

Wavelength dispersion (46) and spatial light modulation (50) are combined having regard for polarization management within a feedback control system for dynamically adjusting spectral power distributions among different wavelength channels (12) Micro-optic, hybrid, and planar implementations are proposed along with coupling schemes to larger fiber optic systems (84) Utility is found throughout multi-channel wavelength division multiplexing (WDM) transmission systems

Dynamically configurable spectral filter

A passive polarization converter free of longitudinally-periodic structure

A novel integrated polarization converter based on ultra short bends is presented, which has a potential for low loss and small device size. A conversion value of 85% was experimentally measured with excess loss of 2.7 dB and overall dimensions of 975/spl times/83 /spl mu/m. Also 45% conversion was measured with extremely low excess loss of 0.4 dB for a device size of 760/spl times/86 /spl mu/m.

/pdf/novel-compact-polarization-converters-based-on-ultra-short-rq2pgq5966.pdf

Novel compact polarization converters based on ultra short bends

TE to TM converters with constant 45 degrees operation are a key component in OEICs for coherent optical system applications. A passive TE/TM-mode converter with a laterally tilted rib waveguide fabricated on a stepped substrate is proposed and investigated. The conversion effect has been simulated using scalar and vectorial two-dimensional finite difference methods. The device fabricated on

Passive mode converter with a periodically tilted InP/GaInAsP rib waveguide

An integrated optical circuit comprises a first device and a second device, which devices are connected by a polarization convertor The polarization convertor comprises a curved section of a waveguide, integrated in the optical circuit The curved section may comprise several differently curved subsections The conversion ratio is determined in part by the radius of curvature of the curved subsections as well as by the number of transitions between subsections

Integrated optical circuit comprising a polarization convertor

An optimized integration process is reported requiring only three epitaxial growth steps for the fabrication of an OEIC encompassing a single-mode laser, a waveguide element, and fast photodiodes. The process was applied to the fabrication of a heterodyne receiver including a semi-insulating buried heterostructure (SIBH)-DFB-laser with an output power of 14 mW and a side-mode suppression ratio greater than 40 dB, a 3-dB coupler, and high-speed balanced photodiodes with a bandwidth of 9 GHz. The laser can also be used as a transmitter laser exhibiting a modulation bandwidth of 11 GHz.

Fabrication of a heterodyne receiver OEIC with optimized integration process using three MOVPE growth steps only

Making a monolithic micro-system, e.g. an opto-electronic integrated chip (OEIC) with at least one optical connecting and/or disconnecting device is already very largely prepared in the masking set for the structures to be formed on the same substrate (1) from a III-V semiconductor material. An etched pit (11) for the optical fibre (3) is embedded therein and a surface strip waveguide (2) having an end surface (13) produced by micro-separation is also used. The waveguide (2) may take the form of an asymmetrical waveguide taper (7) or the fibre (3) may be given a taper or a micro-optical component may be fitted between the two light guides (2, 3). Such monolithically integrated light guide connections are needed in the use of devices, chips and integrated optical components at the fibre optics interface.

Helmut Dr.-Ing. Heidrich

Papers

Novel compact polarization converters based on ultra short bends

Passive mode converter with a periodically tilted InP/GaInAsP rib waveguide

Integrated optical circuit comprising a polarization convertor

Fabrication of a heterodyne receiver OEIC with optimized integration process using three MOVPE growth steps only

Lichtleiterverbindung zum verkoppeln eines wellenleiters und einer faser