Fig. 1. (a) Schematic representation of a 4×1 “diagonal line” mesh and (b) its implementation on a conventional silicon photonic platform. The overall footprint of the circuit is 3.7 mm by 1.5 mm and is mounted on a PCB with a CMOS ASIC for the readout of the on-chip sensors and driving the integrated thermal tuners.

Fig. 2. Compensation of near-field amplitude and phase perturbations. (a) Optical setup employed to introduce intentional perturbations in the near field generated by the output RPs of the mesh. An amplitude/phase mask is placed in the image plane P2, and the far-field pattern is measured in plane P3 by a near-IR camera. In the inset the measured field in the image plane P2 is shown. (b) Compensation of pure phase perturbations: (b₁) reference far-field pattern with nominal RPs (same amplitudes and phases) and no mask in the system; (b₂) effect of a [π0π0] phase mask; (b₃) recovery of the nominal far field after mesh tuning; (b₄) far field measured after mesh tuning if the phase mask is removed. (c) Compensation of amplitude and phase perturbations: (c₁) reference far-field pattern with nominal fields at the RPs and no mask in the system; (c₂) effect of a mask with [π0π/9π/9] phase profile and [110.20.2] amplitude profile; (c₃) recovery of the nominal far field after mesh tuning; (c₄) far field measured after mesh tuning if the phase mask is removed. Input optical power is increased in this experiment to maintain the clarity of pictures due to the loss introduced by the mask, since this is a passive mesh (i.e., with no amplification).

Fig. 3. Compensation of far-field perturbations. (a) Optical setup employed to introduce intentional perturbations in the far field generated by the mesh. An obstacle is placed between the mesh and the camera with no other optical elements along the path. (b) Imaging through a phase mask: (b₁) reference far-field pattern with nominal RPs (sample amplitudes and phases) and no mask in the system; (b₂) effect of a [π0π0] phase mask introduced in the far field; (b₃) recovery of the nominal far field after mesh tuning; (b₄) far field measured after mesh tuning if the phase mask is removed. (c) Imaging through a diffusive medium: (c₁) reference far-field pattern with nominal fields at the RPs and no obstacle in the system; (c₂) effect of scattering medium (scotch tape) introduced in the far field; (c₃) recovery of the nominal far field after mesh tuning; (c₄) far field measured after mesh tuning if the diffusive medium is removed.

Fig. 4. Obstacle identification: (a₁) reference far-field pattern with nominal RPs and no mask in the system; (a₂) effect of an unknown mask introduced in the near-field setup of Fig. 2; (a₃) recovery of the nominal far field after mesh tuning; (a₄) far field measured after mesh tuning if the mask is removed. This profile corresponds to an RP phase correction of [ππ00], thus indicating that the mask has a phase profile of [−π−π00].

Fig. 5. (a) Photograph of the phase mask employed to introduce intentional perturbation of the field at the RPs of the mesh; (b) photograph of the silicon chip assembled onto the electronic PCB; (c) schematic of the experimental setup employed to create a one-to-one replica of the field at the RPs in plane P2. (d) Image of the four RPs’ fields measured in plane P2.

Fig. 6. (a) Top-view photomicrograph of the uniform linear array of optical radiation elements consisting of vertical grating couplers spaced by 127 μm; (b) simulated far-field pattern of the four-element array in the azimuth direction (parallel to the array) at an elevation angle of 0 deg. (c) Simulated and (d) measured 2D field pattern within an azimuth range of ±2.2 deg (horizontal axis) and an elevation range of ±4 deg (vertical axis). The vertical dashed blue line indicates the reference central axis of the camera.

Fig. 7. (a) Simulated and (measured) 2D far-field pattern of the four-element array when a phase profile of [π0π0] is applied to the field emitted by the four RPs. The vertical dashed blue line indicates the reference central axis of the camera.

Fig. 8. (a) Simulated 2D far-field pattern of the four-element array when a phase profile of [π0π/9π/9] and an amplitude modulation proportional to [110.20.2] are applied to the field emitted by the four RPs. (b) Simulated 2D far-field pattern of the four-element array when a phase profile of [−π0−π/9−π/9] and an amplitude modulation proportional to [0.20.211] are applied to the field emitted by the four RPs.