Expanding the adiabatic design toolbox - more modes, parameters and versatility.

Adiabatic design principles can be used to improve the performance of many photonic components. The recently published adiabatic optimization method, MODALL, relies on a design rule that guarantees adiabaticity and enables optimization of adiabatic photonic components against multiple dimensions and radiation modes. In this work, MODALL is extended to enable optimization of multi-mode components, optimization against an extra degree of freedom and optimization of modal crosstalk. We present a derivation of these extensions starting from MODALL theory and verify them via the design, fabrication and characterization of a mode multiplexer with ultra-low crosstalk: worst-case <-38 dB and median <-45 dB. These design extensions will aid the adiabatic design optimization of many photonic components including splitters, polarization rotators, interlayer transitions and edge couplers.

Adiabatic guided wave optics - a toolbox of generalized design and optimization methods.

Starting from the fully vectorial coupled local-mode theory, a general design rule for adiabatic waveguide design is derived. The design rule guarantees adiabaticity and puts an upper limit on the transmission loss of any guided wave transformation. The rule is applicable to any waveguide geometry, admits multi-dimensional optimization, and accounts for radiative loss to guided and radiation modes. Moreover, the design technique is enhanced with further optimization procedures that eliminate coupling between particular pairs of modes. The utility of this toolbox of design rules and methods is illustrated through the design of a 2×2 coupler and a bilayer waveguide transition. These design procedures can be used to optimize single-mode and multimode photonic devices by varying one or more waveguide parameters.

Beyond Young's experiment: time-domain correlation measurement in a pinhole array.

Time-domain analysis of field correlations provided by the interferogram from a nonredundant pinhole array is performed. It is shown that the described single measurement is identically equal to a series of Young's two-pinhole experiments. Proper postmeasurement analysis, taking into account the finite coherence time of the source, results in a sampling of the spatial-temporal coherence function.

Field transfer decay and interferometry in coupled waveguides with stochastic sources.

Coupled waveguides, such as those used as optical filters, switches, or couplers, are investigated in the context of coherence theory. A stochastic source is introduced to the standard coupled-mode model. Decay in the power transferred between the waveguides as a function of distance is predicted. Application of this result in the form of an interferometric spectrometer is explored.

Stochastic coupled mode theory for partially coherent laser arrays.

Partially coherent, transversely coupled laser arrays are investigated within a stochastic coupled mode formalism. Predictions of the coherence or correlation functions in both the spectral and time domains are made. It is demonstrated that the coherence properties of the system in both domains are strongly dependent on the number and intensity of coupled modes. The theory can be useful for the study of semiconductor laser arrays, particularly vertical-cavity surface-emitting laser arrays.