Coupling structure for optical fibres and process for making it

A coupling structure for optical coupling between an optical fibre and an optical device comprising:

• a first substrate having a front main surface;
• at least a guidance channel which extends through said first substrate from the front main surface to an opposite rear main surface, said guidance channel being configured so as to optically confine the light propagating therethrough;
• and
• a second substrate in which a via hole for insertion of the optical fibre is formed such that the via hole goes through said second substrate from a front main surface to an opposite rear main surface of said second substrate, said second substrate being placed on the first substrate with its opposite rear main surface adjacent to the first main surface of the first substrate so that the via hole of the second substrate is substantially in alignment with the guidance channel of the first substrate.

A method for producing a semiconductor coupling structure comprising the successive steps of:

• providing a first silicon substrate having opposite front and rear surfaces;
• etching to form a substantially vertical trench from the front surface in the first semiconductor substrate;
• forming a first layer of silicon oxide material on the inner walls of the trench and on the upper surface of said substrate near said trench, said first silicon oxide layer having a first refractive index;
• forming a second layer of silicon oxide material over said first layer so as to fill the trench, said second silicon oxide layer having a second refractive index larger than the first refractive index of the first silicon oxide layer;
• planarising the second silicon oxide layer to expose the first silicon oxide layer in the trench and to form a planar surface;
• and
• back etching said first silicon substrate from the rear surface to expose the first and the second silicon oxide layers.

An optical package comprising:

• a housing having a cavity and an aperture;
• at least an optical device fixed in the cavity of the housing and optically aligned with the aperture;
• a coupling structure for coupling of an optical fibre to the optical device, which is capable of dosing the aperture of the housing, wherein said coupling structure comprises:
• a first substrate having a front main surface;
• at least a guidance channel which extends through said first substrate from the front main surface to an opposite rear main surface, wherein said guidance channel is configured so as to confine the light propagating therethrough;
• and
• a second substrate in which a via hole for insertion of the optical fibre is formed such that the via hole goes through said second substrate from a front main surface to an opposite rear main surface of said second substrate, said second substrate being placed on the first substrate with its opposite rear main surface adjacent to the first main surface of the first substrate so that the via hole of the second substrate is substantially in alignment with the guidance channel of the first substrate