CROSS-REFERENCE TO RELATED APPLICATION

This U.S. nonprovisional application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2019-0040147 filed on Apr. 5, 2019 in the Korean Intellectual Property Office, the disclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

The present inventive concepts relate to an optical device and a method of fabricating the same.

With the development of optical communication technology, techniques have been studied for optical devices including optical splitters, optical couplers, optical switches, optical wavelength dividers, and optical amplifiers. In general, to achieve optical devices on chips based on specific materials, an etching process is required to pattern a material after the deposition of the material on a substrate. The optical loss of the optical device is mainly determined by optical adsorption of deposited material and scattering caused by surface roughness of the optical device. In particular, the scattering due to the surface roughness is a main factor to determine the optical loss. The surface roughness of the optical device is chiefly originated from the etching process on the deposited material. In the case the deposited material is not silicon, silicon nitride, or silicon oxide widely used for semiconductor processes, it is much likely that no optimization is often achieved in the etching process. Therefore, after the etching process, an extremely poor surface roughness occurs to dramatically reduce optical characteristics of the optical device.

SUMMARY

Some example embodiments of the present inventive concepts provide an optical device with improved optical characteristics.

Some example embodiments of the present inventive concepts provide a method of fabricating an optical device with improved optical characteristics.

According to some example embodiments of the present inventive concepts, an optical device may comprise a first sub-chip and a second sub-chip flipped over on the first sub-chip. The first sub-chip may include a first substrate, a first lower cladding pattern on a first surface of the first substrate, and a first core layer on the first lower cladding pattern. The second sub-chip may include a second substrate, a second lower cladding pattern on a second surface of the second substrate, and a second core layer on the second lower cladding pattern. The first surface of the first substrate may face the second surface of the second substrate. The first lower cladding pattern may have a first top surface parallel to the first surface and a first sidewall inclined to the first surface. The first core layer may include a first core part on the first top surface and a first side part on the first sidewall.

According to some example embodiments of the present inventive concepts, an optical device may comprise a first sub-chip and a second sub-chip flipped over on the first sub-chip. The first sub-chip may include a first substrate, a first lower cladding pattern on a first surface of the first substrate, and a first core layer on the first lower cladding pattern. The second sub-chip may include a second substrate, a second lower cladding pattern on a second surface of the second substrate, and a second core layer on the second lower cladding pattern. The first surface of the first substrate may face the second surface of the second substrate. A width of the first lower cladding pattern may decrease as approaching the second substrate. A width of the second lower cladding pattern may decrease as approaching the first substrate. A core part of the first core layer may be adjacent to a core part of the second core layer.

According to some example embodiments of the present inventive concepts, an optical device may comprise: a lower cladding pattern on a substrate; and a core layer on the lower cladding pattern. The lower cladding pattern may have a top surface parallel to a top surface of the substrate and a sidewall inclined to the top surface of the substrate. The core layer may have a core part on the top surface of the lower cladding pattern and a side part on the sidewall of the lower cladding pattern. The core layer may include a first core layer and a second core layer. The first core layer of the core part may have a first thickness. The first core layer of the side part may have a second thickness in a direction perpendicular to the sidewall. The first thickness may be greater than the second thickness.

