Arrayed Multimode Fiber to VCSEL Coupling for Short Reach Communications Using Hybrid Polymer-Fiber Lens

We describe the main recent technological approaches that associate micro-optical elements to VCSELs in order to control their output beam and to improve their photonic integration. These approaches imply either a hybrid assembly or a direct integration technique. They are compared with regards to their tolerance to alignment errors and to their ease of implementation onto arrays of devices at a wafer level. In particular, we detail the integration techniques we have developed for self-aligned polymer microlens fabrication for beam collimation and short distance beam focusing. Finally, designs to achieve active micro-optics or to exploit novel nanophotonic effects are discussed.

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“…The use of polymer-lensed fibers instead of standard ones was also proposed to improve tolerances [22] as well as the polymer bonding of 90…”

Section: Passive Micro-optics For Vcsel: Hybrid Assemblymentioning

confidence: 99%

Collective Micro-Optics Technologies for VCSEL Photonic Integration

Bardinal

Camps

Reig

et al. 2011

Advances in Optical Technologies

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“…It is also well understood that this comes at the expense of an increase in sensitivity to angular misalignment, which is however relatively easier to control than lateral misalignment with an appropriate mechanical design during assembly as long as it is above a 0.1 • -limit [8]. For fiber-coupled lasers, beam expansion/collimation is usually achieved by integrating hemispherical lenses at the tip of the fiber [9], [10] or with the use of a ball lens [11], [12]. On-chip beam expansion has been recently demonstrated using both edge couplers with 3D-printed optics [13] and grating couplers combined with mounted microlens array blocks [14], ball-lens [15] or polymer microlens [16].…”

Section: Introductionmentioning

confidence: 99%

Expanded-Beam Backside Coupling Interface for Alignment-Tolerant Packaging of Silicon Photonics

Mangal

Snyder

Campenhout

et al. 2020

IEEE J. Select. Topics Quantum Electron.

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We demonstrate an alignment-tolerant backside coupling interface in the O-band for silicon photonics by generating an optimized through-substrate (downward) directionality beam from a TE-mode grating coupler and hybrid integrating the chip with backside silicon microlenses to achieve expanded beam collimation. The key advantage of using such an expanded beam interface is an increased coupling tolerance to lateral and longitudinal misalignment. A 34 µm beam diameter was achieved over a combined substrate thickness of 630 µm which was then coupled to a thermally expanded core single-mode fiber to investigate the tolerances. A 1-dB fiber-to-microlens lateral alignment tolerance of 14 µm and an angular alignment tolerance of 1 • was measured at a wavelength of 1310 nm. In addition, a large ±2.5 µm 1-dB backside alignment accuracy was measured for the placement of microlens with respect to the grating. The radius of curvature of Si microlens to achieve a collimated beam was 480 µm, and a 1-dB longitudinal alignment tolerance of 700 µm was measured for coupling to a single-mode expanded core fiber. The relaxation in alignment tolerances make the demonstrated coupling interface suitable for chip-to-package or chip-to-board coupling.

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