1,720,964 research outputs found
Waveguide-based technique for wafer-level measurement of phase and group effective refractive indices
No full textA novel optical technique for multipoint on-wafer testing is reported. The technique exploits an integrated optical waveguide named point reflector optical waveguide (PROW) carrying multiple sensing probes based on lumped reflectors. PROW can be placed on the wafer along the desired paths, is compatible with chips tiling, requires a very small dedicated area and is here exploited to map the on-wafer distribution of the phase and group effective indices with an accuracy down to 10-3. The technique is useful to retrieve and map the variations of the physical and geometrical properties of the waveguides (e.g., width and core material composition) on the investigated wafer area. The potential of the PROW is here demonstrated on a InP wafer but can be readily extended to other platforms
Reconfigurable photonic integrated mode (de)multiplexer for SDM fiber transmission
Get PDFSpatial division multiplexing in multi-mode fibers allows to largely enhance transmission capacity compared to single-mode links. Photonic integrated circuits can provide solutions for mode multiplexing at the transmitter and demultiplexing at the receiver but have to generally face high losses and inter-modal cross-talk issues. Here a photonic circuit for efficient mode multiplexing and demultiplexing in few-mode fibers is presented and demonstrated. Two 10 Gbit/s channels at the same wavelength and polarization are simultaneously transmitted over modes LP01 and LP11a of a few-mode fiber relying only on integrated mode MUX and DEMUX. The proposed Indium-Phosphide-based circuits have a good coupling efficiency with fiber modes and mode-dependant loss smaller than 1 dB. Measured mode excitation cross-talk is as low as -20 dB and a channel cross-talk after propagation and demultiplexing of -15 dB is achieved. An operational bandwidth of the full transmission system of at least 10 nm is demonstrated. Both mode MUX and DEMUX are fully reconfigurable and allow a dynamic switch of channel routing in the transmission system. These results enable fully-integrated fiber mode handling for high-bandwidth flexible optical networks
Integrated Indium-Phosphide-Based Mode Multiplexer and Demultiplexer for Reconfigurable Mode Division Multiplexing Transmission
No full textWe show a MDM transmission system exploiting integrated photonic circuits for channels (de)multiplexing over modes LP01 and LP11a of a few-mode fiber. Arbitrary selection of channels routing in the system is demonstrated as well
An improved model to predict thermo-optic coefficient in InGaAsP waveguides
No full textIn this paper, we present an extension of the modified single oscillator model able to predict the temperature related variations of refractive index of InP/InGaAsP materials. Model is based on three parameters- oscillation energy, dispersion energy and bandgap energy. The proposed model enables to calculate the thermo-optic coefficient in the typical telecommunication wavelength range. The obtained numerical results are compared with experimental data and found in good agreement
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Wavelength and composition dependence of the thermo-optic coefficient for InGaAsP-based integrated waveguides
Get PDFA method to take into account the wavelength, composition, and temperature dependencies in the calculation of the refractive index and linear thermo-optic coefficient of In1−xGaxAsyP1−y alloys is presented. The method, based on the modified single oscillator model, shows a good agreement with experimental data for InP reported in literature at different wavelength and temperature ranges. Further, we exploit this approach with a Film-Mode Matching solver to calculate the linear thermo-optic coefficients of both phase and group effective indices of an InGaAsP-based waveguide. The same waveguide structure is also experimentally investigated through a reflectometric technique and results are found to be in accordance with the simulations performed exploiting the proposed method. In both cases, a dependence of the group index on temperature, almost twice that of the phase index, is observed. These results provide a deeper understanding on the influence of the temperature on the behaviour of optical waveguides and devices, making possible an accurate and realistic modelling of integrated circuits
Integrated all-optical MIMO demultiplexer for mode- and wavelength-division-multiplexed transmission
Get PDFA photonic integrated circuit performing simultaneous mode and wavelength demultiplexing for few-mode-fiber transmission is demonstrated for the first time. The circuit is realized on an InP-based technological platform; it can handle up to eight mode- and wavelength-division-multiplexed (MDM/WDM) channels and allows all-optical multiple-input-multiple-output processing to unscramble mode mixing generated by fiber propagation. A single arrayed waveguide grating is used to demultiplex the WDM channels carried by all the propagating modes, optimizing circuit complexity, chip area, and operational stability. Combined with an integrated wideband mode multiplexer the circuit is successfully exploited for the transmission of 10 Gbit/s on-off-keying non-return-to-zero channels with a residual cross talk of about -15 dB
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Integrated 8-Channel Mode and Wavelength Demultiplexer for MDM and WDM Transmission over Few-Mode Fibers
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