Search

weighted thinned linear array with pattern reconfigurable antenna elements is proposed to overcome the disadvantages of traditional millimeter wave phased arrays, such as, narrow scanning range, high grating lobes. The developed array can scan its main beam from φ = -76° to 76° in H-plane and has 3 dB beam coverage from φ = -88° to 88° with low grating lobes by shifting two operating states of the elements and adjusting the feed phases. [ABSTRACT FROM AUTHOR]

A broadband achromatic phase retarder in the full visible region (wavelength λ∈[400,800 nm]) using subwavelength grating (SWG) is designed, fabricated and tested. For the first time, it is experimentally proved that the achromatic phase retarder in the full visible region can be realized by SWG. An improved method combining enumeration with optimization for designing the achromatic phase retarder with rectangular and sinusoidal SWG is presented. Rigorous coupled wave theory (RCWT) is applied to calculate the diffraction performances. Examples show that the designed phase retarders perform broadband achromatic phase retardation successfully. Compared with the previous methods, the improved method shows the advantages of good versatility and flexibility. [Copyright &y& Elsevier]

An integrated diffractive optical mode converter, which can be integrated into planar lightwave circuits (PLCs), consisting of a diffractive optical element (DOE) and a slab waveguide is presented for fiber-to-waveguide coupling. The DOE is designed using iterative phase retrieval algorithm. In the iterative algorithm, we introduce a new modification of far-field amplitude constraint to provide very high mode conversion quality. Compared with previously published mode converters, the scheme is more universal because it is applicable for any waveguide structure. In simulation, coupling losses lower than 0.12 dB have been reached for all the discussed waveguides. The converter is shown to be polarization-insensitive and applicable in multi-wavelength PLCs. And the tolerance on axis misalignment has been investigated. [Copyright &y& Elsevier]

An integrated mode converter consisting of two diffractive optical elements (DOEs) and a Silicon slab is presented for low-loss coupling between a semiconductor laser diode (LD) and a single-mode fiber (SMF). The phase structures of the DOEs are designed using iterative phase retrieval algorithm. We introduce a new far-field amplitude constraint into the iteration to provide very high mode conversion quality. Compared with previously published mode converters, the scheme is more universal because it’s applicable for any semiconductor LD. In simulation, coupling losses lower than 0.02 dB are predicted for all the discussed LDs with aspect ratios of the elliptical fields from 1 to 9. The requirements on axial displacement and rotation angle have been removed. The tolerance for 1-dB loss increment for lateral misalignment is 0.9 μm. And the coupling loss is insensitive to tilt angle. [Copyright &y& Elsevier]