Light emitting device, manufacturing method thereof, and optical transceiver
The light emitting device includes an active layer formed on a semiconductor substrate for emitting light, a semiconductor layer of a first conductivity type electrically connected to one end of the active layer, a semiconductor layer of a second conductivity type electrically connected to the other end of the active layer, first and second electrodes, a feedback mechanism for laser oscillation, and a waveguide for guiding the light emitted from the active layer, in which the active layer is made of a semiconductor having an affinity with a silicon CMOS process, and the semiconductor layer of the first conductivity type and the semiconductor layer of the second conductivity type, and the waveguide are each made of silicon as a part of the semiconductor substrate.
1. A light emitting device, comprising:
an active layer, formed on a semiconductor substrate, for emitting light, the active layer including:
a central region, and
a mode conversion region that tapers, in thickness and width, along the optical axis;
a semiconductor layer of a first conductivity type electrically connected to one end of the active layer;
a semiconductor layer of a second conductivity type electrically connected to the other end of the active layer;
first and second electrodes;
a feedback mechanism for laser oscillation; and
a waveguide for guiding the light emitted from the active layer,
wherein the active layer is made of a semiconductor having an affinity with a silicon CMOS process,
wherein the semiconductor layer of the first conductivity type, the semiconductor layer of the conductivity type, and the waveguide are each made of silicon as a part of the semiconductor substrate, and
wherein the mode conversion region couples the emitted light to the waveguide to minimize optical loss.
2. The light emitting device according to claim 1 , wherein the waveguide is adjacent to the active layer in such a manner as to be optically coupled to the active layer.
3. The light emitting device according to claim 1 , wherein the semiconductor substrate is a substrate made of silicon, a silicon dioxide, and silicon.
4. The light emitting device according to claim 3 , wherein silicon has the largest refractive index among the materials composing the waveguide.
5. The light emitting device according to claim 2 , wherein the mode conversion region of the active layer becomes thinner in film thickness as approaching the waveguide along the optical axis.
6. The light emitting device according to claim 2 , wherein the mode conversion region of the active layer becomes narrower as approaching the waveguide along the optical axis.
7. The light emitting device according to claim 5 , wherein an interface between the active layer and the semiconductor substrate and an interface on a side opposite to the active layer and the semiconductor substrate are approximately parallel to each other.
8. The light emitting device according to claim 1 , wherein the active layer is composed of either germanium or silicon/germanium.
9. The light emitting device according to claim 1 , wherein the mode conversion region tapers to a point proximate to the waveguide.
10. The light emitting device according to claim 1 , wherein the feedback mechanism includes Bragg reflectors.