Wavelength selective optical focusing device using optical fiber and optical module using the same

An optical module comprising:

• a sub-mount;
• an optical focusing device mounted on the sub-mount, comprising
• a core having a cross-sectional shape and elongated over a length for transmitting an optical signal therethrough and
• a cladding layer surrounding the outer surface of the elongated core and having a plurality of grooves formed in the outer circumferential surface of a portion of the cladding layer of an optical fiber such that each groove has a depth and an interval is the distance between two adjacent grooves, wherein the intervals are gradually increasing or decreasing, wherein an optical signal having a designated wavelength guided by the core is focused through the cladding layer to the outside of the cladding layer by the grooves, and wherein the optical signal is focused perpendicular to the optical axis;
• and
• an optical element arranged on the sub-mount at a position, onto which the optical signal is focused by the optical focusing device, for receiving or transmitting the optical signal.

An optical fiber comprising:

• a core having a cross-sectional shape and being elongated over a length for transmitting an optical signal therethrough;
• and
• a cladding layer surrounding the outer surface of the elongated core,
• wherein a plurality of grooves are formed to have openings on a portion of the outer circumferential surface such that each groove has a depth and an interval is the distance between two adjacent grooves,
• wherein the intervals are gradually increasing or decreasing, and
• wherein an optical signal having a designated wavelength guided by the core is focused through the cladding layer to the outside of the cladding layer by the grooves, and wherein the optical signal is focused perpendicular to the optical axis.