Planar optical waveguide and optical module
The present disclosure relates to a planar optical waveguide and an optical module. A planar optical waveguide according to the present disclosure includes a core and dads provided at an upper portion and a lower portion of the core, respectively, and an end of an upper clad facing a light source is polished to form a first refractive surface inclined at a first angle to refract a light emitted to the upper portion of the core and guide the light to the core. The refractive surfaces are formed at the upper clad and the lower clad of the planar optical waveguide in consideration of beam characteristics of the light source to reduce optical coupling loss without a separate optical waveguide lens.
1. A planar optical waveguide comprising a core and upper and lower clads provided at an upper portion and a lower portion of the core, respectively,
wherein an end of the upper clad facing a light source is polished to form a first refractive surface inclined at a first angle to refract light emitted to the upper portion of the core and guide the light to the core, and
wherein an end of the lower clad facing the light source is processed to form a trench having a second refractive surface inclined at a second angle to refract light emitted to the lower portion of the core and guide the light to the core.
2. The planar optical waveguide of claim 1 , wherein the first angle and the second angle are set depending to a refractive index of a clad material and radiation characteristics of the light source.
3. The planar optical waveguide of claim 1 , wherein the end of the lower clad facing the light source further includes an adhesive surface, which is bonded to a side surface of a substrate on which the light source is mounted, to allow the light source to maintain a certain distance from the core of the planar optical waveguide.
4. The planar optical waveguide of claim 3 , wherein the adhesive surface of the lower clad is formed to allow an emission surface of the light source to be spaced apart from the core at a certain distance.
5. The planar optical waveguide of claim 1 , wherein the first refractive surface and the second refractive surface are applied with a polymer material and a silicone adhesive having a higher refractive index than a clad material to minimize rough surfaces formed on the first and second refractive surfaces by being polished or processed.
6. An optical module comprising a light source, a substrate on which the light source is mounted, and a planar optical waveguide,
wherein, in the planar optical waveguide, an end of an upper clad facing the light source is polished to form a first refractive surface inclined at a first angle to refract a light emitted to an upper portion of a core and guide the light to the core, and
wherein an end of a lower clad facing the light source is processed to form a trench having a second refractive surface inclined at a second angle to refract light emitted to the lower portion of the core and guide the light to the core.
7. The optical module of claim 6 , wherein the end of the lower clad facing the light source is bonded to a side surface of a substrate on which the light source is mounted to allow the light source to maintain a certain distance from the core.
8. A method of manufacturing a planar optical waveguide, the method comprising:
forming a lower clad layer as a plate type substrate;
forming a core layer on the lower clad layer;
forming an upper clad layer on the core layer;
forming a first refractive surface inclined at a first angle at an end of the upper clad layer facing a light source to refract a light emitted to an upper portion of the core layer and guide the light to the core layer; and
forming a trench having a second refractive surface inclined at a second angle at an end of the lower clad layer facing the light source to refract light emitted to a lower portion of the core layer and guide the light to the core layer.
9. The method of claim 8 , further comprising:
forming an adhesive surface bonded to a side surface of a substrate on which the light source is mounted at a lower portion of the trench of the end of the lower clad layer facing the light source to allow the light source to maintain a certain distance from the core layer of the planar optical waveguide.
10. The method of claim 9 , wherein in the forming of the adhesive surface, the adhesive surface is polished to have a polishing depth set with respect to the core layer.