Experimental implementation of fiber optic bundle array wide FOV free space optical communications receiver

Abstract

A gimbal-free wide field-of-regard (FOR) optical receiver has been built in a laboratory setting for proof-of-concept testing. Multiple datasets are presented that examine the overall FOR of the system and the receiver's ability to track and collect a signal from a moving source. The design is not intended to compete with traditional free space optical communication systems, but rather offer an alternative design that minimizes the number and complexity of mechanical components required at the surface of a small mobile platform. The receiver is composed of a micro-lens array and hexagonal bundles of large core optical fibers that route the optical signal to remote detectors and electronics. Each fiber in the bundle collects power from a distinct solid angle of space and a piezo-electric transducer is used to translate the micro-lens array and optimize coupling into a given fiber core in the bundle. The micro-lens to fiber bundle design is scalable, modular, and can be replicated in an array to increase aperture size.

Fabrication of microlens based on overplating in electroforming

“…As an important kind of micro-optical device, microlenses play an irreplaceable role in various applications. For example, beam shaping in illumination components [1]; optical coupling in photo-communication [2]; improvement of the collection efficiency in CCDs [3]; 3D imaging [4]; Hartmann wave sensor [5], etc. Correspondingly, a variety of fabrication methods have been developed to fabricate microlenses, such as photoresist thermal reflow [6]; ink jet printing [7]; laser ablation [8]; wet etching [9] and precision machining [10], etc.…”

Wavelength dependence of a fiber-bundle based FSO link

“…For longer distances and outdoor environments, the presence of atmospheric turbulence and weather can produce signal fade or loss for traditional FSO designs. Solutions that increase the transmitter power, the collecting area of the receiver, or the number of spatially diverse transmitter-receiver pairs [1][2][3][4][5][6][7][8][9] have limited utility in the mobile scenario by practical limits on the size, weight, and power consumption (SWaP) of the mobile transceivers that are imposed by the moving platform's capabilities. While several design solutions have been proposed to address these issues, there remains room for new FSO system designs to further improve upon the performance of mobile FSO.…”