External cavity laser using vertical-cavity surface-emitting laser and silicon optical element
Provided is an external cavity laser (ECL) including a vertical cavity surface emitting laser (VCSEL)-Distributed Bragg Reflector (DBR) type light emitting unit configured to receive a current and emit light, and including a DBR function layer and an active layer for a quantum well formed on one side of this DBR function layer, and an optical circuit unit including a light guide in which one end surface is installed to face an active layer at one side of the active layer, light generated from the active layer is received and guided, and an optical axis is formed vertically to an active layer plane, a reflection pattern that is formed at one side of the light guide so as to receive light output from the other end of the light guide to reflect the light again to the light guide, and an external layer for surrounding the light guide and the reflection pattern, wherein the VCSEL-DBR type light emitting unit and the optical circuit unit are mutually coupled to each other. An optical coupling efficiency in the ECL may be raised by improving an inefficient optical coupling issue including alignment, reflection, and the like in a coupling part of a gain element and a silicon waveguide.
1. An external cavity laser (ECL) comprising:
a vertical cavity surface emitting laser (VCSEL)-Distributed Bragg Reflector (DBR) type light emitting unit configured to receive a voltage and emit light, and comprising a first side DBR function layer and an active layer for a quantum well laminated on a second side surface opposite to a first side of the first side DBR function layer; and
an optical circuit unit comprising a light guide in which one end surface is installed to face the active layer at the second side of the active layer, light generated from the active layer is received and guided in the one end surface, and an optical axis is formed vertically to a plane formed by the active layer, a second side DBR functional pattern (reflection pattern) formed at a second side of the light guide so as to receive light output from a second end surface of the light guide to reflect the light again to the light guide, and an external layer configured to surround the light guide and the second side DBR functional pattern,
wherein the VCSEL-DBR type light emitting unit and the optical circuit unit are characterized by being mutually coupled to each other.
2. The external cavity laser of claim 1 , wherein, in the light emitting unit, a Group III-V semiconductor spacer layer is formed on a surface of the active layer, and
when the spacer layer is formed, a light guiding region having a larger refractive index than a peripheral region is characterized by being provided in the spacer layer that corresponds to a light emitting region in which light emission is concentrated in the active layer.
3. The external cavity laser of claim 2 , wherein a substrate of the light emitting unit and the Group III-V semiconductor space layer are characterized by being manufactured on the basis of Indium phosphide (InP).
4. The external cavity laser of claim 1 , wherein the light guide and the second side DBR functional pattern are characterized by being formed of silicon, and the external layer is characterized by being formed of any one among an oxide film, a silicon nitride film, or a silicon oxide nitride film.
5. The external cavity laser of claim 1 , wherein an anti-reflection film is characterized by being formed on at least one of the one end surface of the light guide and a surface facing the one end surface.
6. The external cavity laser of claim 1 , wherein the light guide comprises:
a tapered part formed of a rectangular tapered pillar in which a width is gradually reduced starting at the one end side and away from the light emitting unit;
a channel part in a rectangular pillar type in which a width is constant; and
a fan-shaped part forming a fan shape with a width extending as being away from the light emitting unit,
wherein the second side DBR functional pattern is characterized by being formed of one or more circular arc patterns that are parallel at an identical central angle and are separated from a circular arc of the fan-shaped part.
7. The external cavity laser of claim 1 , wherein a size of the light emitting region of the VCSEL-DBR type light emitting unit and a light intensity distribution in the light emitting region are characterized by being respectively matched with a size and a light intensity distribution of the one end surface.
8. The external cavity laser of claim 1 , wherein a wavelength variable filter is characterized by being further installed in a middle of the light guide.
9. The external cavity laser of claim 1 , wherein an emissive light guide separate from the light guide is characterized by being further coupled to the second side of the second side DBR functional pattern to be used as an optical transmitter and receiver.