Fig. 10: Microlens scalability.
From: An integrated photonic engine for programmable atomic control
a The nearfield phase and amplitude upon the SLM plane are related to the farfield output by a Fourier transform. While a perfect parabolic lens results in a perfect focused farfield spot, the incorporation of various non-idealities reduces the power efficiency of coupling. Treated here are the most relevant errors: the discrete sampling of phase from each SLM pixel, and the blurring of phase between pixels expected to occur on hardware. Here, this effect is modeled as a symmetric exponential e−∣x∣/α blur with characteristic length α corresponding to a percentage of the pixel width. b From these simulations, we can extrapolate the performance of an array of microlenses for various steering ranges and fill factors. Larger microlens size generally monotonically corresponds to greater efficiency, so for each case we mark the smallest size of the microlens that is more than 80% efficient. Reciprocal to this is the related figure of merit of microlens number N = AHD/Γ2 which can be packed onto an HD SLM with pixel area AHD. The parameters used in this work are indicated by the red crosses.
