FIELD

The present disclosure relates to photonic chip features for prevention of adhesive spread and photonic chip features for fiber attachment into grooves, and in particular to methods and products relating thereto.

BACKGROUND

A photonic integrated circuit (PIC) die processes photons versus electrons in an integrated circuit (IC) that are ubiquitous in our world. After singulating the die from a wafer, the die is placed into a package (typically ceramic or low thermal coefficient metal) or in some cases directly onto a PCB by a thermally cured die attach adhesive after precise placement. In the current IC manufacturing environment based on electrical signal manipulation, this is where the IC die is wire bonded to various packaging formats to interface to the outside environment. Various IC packaging methods exist for interfacing the electrical signals on the die. With a PIC die, the equivalent connection is with optical fibers and or optical fiber arrays. These delicate fibers need to be precisely positioned to optical waveguides on the die and attached in a robust method. The method of attachment must both prevent damage to the fiber and maintain efficient power coupling of the signal to the optical circuit. Two approaches typically used are edge coupling and surface gratings. Surface gratings have a bit more forgiveness in position but require more area of the die surface.

As a part of the wafer manufacturing process used to create the photonic chips, a trench is sometimes etched around the periphery of Silicon Photonic chips which creates a recessed rim once the chips are diced. This is done to prevent the waveguides that extend to the edge of the chips from being damaged when the Silicon wafers are diced. Fibers and/or fiber arrays are used to couple light from the fibers to the waveguides on the chip. This is done by bringing the fibers and/or fiber arrays up to the edge of the chip, aligning them to the waveguides and then adhesively bonding them to the chip. During the bonding process the adhesive spreads along the edge and the recessed rim of the chip, which prevents additional fibers from being properly aligned with the waveguide.

In the edge coupling approach, numerous implementations exist in research. These include active alignment with no constraints, to grooves (V shaped, U shaped, etc.) with very precise dimensions which have been etched into the chip targeting a more cost-effective passive alignment approach.

The etched grooves provide precisely sized channels that cradle the fibers and/or fiber arrays precisely. The groove width and depth are typically sized so that there is only 1-2 microns of clearance on both sides and below the fiber. In the prior art the grooves have straight edges along their entire length. Because there is little clearance between the fiber and the groove edges, the fiber and/or the chip are easily damaged when the fiber is inserted into the groove.

SUMMARY

In accordance with one aspect of the present disclosure, there is provided a method for attaching an optical fiber to a photonic chip, including:bringing a plurality of optical fibers to an edge of a photonic chip including a trench at the periphery of the photonic chip forming a recessed rim, wherein the recessed rim includes at least one geometric feature separating a plurality of waveguide locations;aligning a first one of the plurality of optical fibers to a first one of the plurality of waveguide locations; andadhesively bonding the first one of the plurality of optical fibers to the photonic chip with adhesive, wherein adhesive flow along the recessed rim of the photonic chip is prevented by the at least one geometric feature from interfering with the attachment of a second one of the plurality of optical fibers.

In accordance with another aspect of the present disclosure, there is provided a photonic chip including: a trench at the periphery of the photonic chip forming a recessed rim, wherein the recessed rim includes at least one geometric feature separating a plurality of waveguide locations, the at least one geometric feature suitable to prevent adhesive flow between the plurality of waveguide locations.

In accordance with another aspect of the present disclosure, there is provided a method for attaching an optical fiber to a photonic chip, including inserting an end of an optical fiber into an optical fiber groove of a photonic chip by guiding the end of the optical fiber into a flared opening of an entrance portion of the optical fiber groove, thereby minimizing damage to at least one of the optical fiber and the photonic chip.

In accordance with another aspect of the present disclosure, there is provided a photonic chip including at least one optical fiber groove which includes an entrance portion and a non-entrance portion, wherein the entrance portion includes a flared opening having a greater clearance than the non-entrance portion.

These and other aspects of the present disclosure will become apparent upon a review of the following detailed description and the claims appended thereto.

