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Flexible optical connector for integrating an external laser with a silicon photonics chip Disclosure Number: IPCOM000245954D
Publication Date: 2016-Apr-20
Document File: 4 page(s) / 419K

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This disclosure describes a flexible optical connector containing single mode polymer waveguides, enabling a direct connection between an external laser chip with a silicon photonic chip. This flexible connector addesses the issue of mode mismatch between the lasers and the silicon waveguides and the issue of different light paths.

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Flexible optical connector for integrating an external laser with a silicon photonics chip

Disclosed is a compact packaging for single-mode active device with a silicon photonics chip relying on a folded/bended waveguide flex interfacing the active devices and the passive silicon-based waveguides independently from the height difference or the share of common substrate or not. Folding/Bending the polymer waveguide flex allows efficient butt-coupling to the active chip on one end, while the other end can be coupled to the silicon photonics chip by so-called adiabatic coupling. The attachment of the flex to the laser array and its design enables an easy access to the metal pads for high-speed electrical connections.

The background of the disclosure consists of the integration of external active components

in the silicon photonics platform, in particular laser sources made of III-V semiconductor materials that are needed for various applications, and commonly divided in three categories: Distributed Bragg Reflector (DFB) lasers, Distributed Feedback (DFB) lasers and Vertical Cavity Surface Emission Lasers (VCSEL). The key issue is to heterogeneously integrate such lasers on a

Silicon-on-Insulator chip. For cost-effectiveness reasons and reduced manufacturing processes, an external subassembly is preferred to a monolithic integration. An external subassembly also facilitates the electrical connections required for a high speed drive. The bottleneck of the VCSEL integration resides in the coupling to silicon waveguides, essentially summed up in two issues: a mode field diameter and distribution mismatch and the orthogonality of the optical axis of the two components, requiring a 90 degree turn in the optical path. In the case of DFB and DBR lasers, the key issues are the mode profile mismatch between the mode at the output facet of the laser and the strong confined mode in the single-mode silicon waveguides, as well as the alignment tolerances.

    The scope of this disclosure is to solve the issue of coupling light from a single mode external active device into a silicon photonic waveguide. This can be decomposed in 5 problems:

- Problem 1: The mode profile at the aperture of a single-mode laser is much bigger than the mode confined in the silicon photonic waveguides (5-6 ┬Ám VCSEL beam waist and same order of magnitude in a laser diode (LD) compared to typical 350-450 nm Si waveguide mode size).

The light is emitted by a single-mode laser device and has to be coupled to single-mode silicon waveguides, creating a stringent condition for the coupling interface.

- Problem 2: In order to comply with high-speed electrical connections, the VCSEL light is emitted in the vertical axis and has to be coupled to silicon waveguide devices with propagation in the horizontal plane. This requires a 90 degree turn along the light path.

- Problem 3: coupling light from a VCSEL to silicon waveguides with the following requirements:

- High coupling effici...