Multi-section high power semiconductor optical amplifier (SOA) and fabrication method thereof
A multi-section semiconductor optical amplifier (SOA) includes at least two sections in series—an input section at an input side and an output section at an output side—with the input section having a higher optical confinement (also referred to as a high gamma) and the output section having a lower optical confinement (also referred to as a low gamma). The input section may also have a shorter length than the output section. The multi-section structure allows optimizing the input side and the output side design separately such that the input section provides a high gain section configured to quickly increase optical power and the output section provides a low differential gain section that improves saturation. As a result, the multi-section SOA can achieve higher output power with high gain and lower signal noise while demanding low input power.
1 . A multi-section semiconductor optical amplifier (SOA), comprising:
an input section disposed at an input side of the semiconductor optical amplifier, the input section having a first optical confinement factor Γ 1 along a first length L 1 of the input section, and wherein the input section provides a first optical gain;
an output section disposed at an output side of the semiconductor optical amplifier and adjacent the input section, the output section having a second optical confinement factor Γ 2 along a second length L 2 of the output section, and wherein the output section provides a second optical gain; and
wherein the first optical confinement factor Γ 1 is higher than the second optical confinement factor Γ 2 , and wherein the first optical gain is higher than the second optical gain.
2 . The multi-section semiconductor optical amplifier according to claim 1 wherein the first optical confinement factor Γ 1 is in a range of 2% to 15% and the second optical confinement factor Γ 2 is in a range of 1% to 9%.
3 . The multi-section semiconductor optical amplifier according to claim 1 wherein the second length L 2 is longer than the first length L 1 .
4 . The multi-section semiconductor optical amplifier according to claim 3 wherein the first length L 1 is in a range of 100 μm to 1 mm and wherein the second length L 2 is in a range of 1 mm to 4 mm.
5 . The multi-section semiconductor optical amplifier according to claim 1 , wherein input section and the output section are formed by a same active region.
6 . The multi-section semiconductor optical amplifier according to claim 5 , further including a substrate, a buffer layer on the substrate, the active region on the buffer layer, and at least one cladding layer on the active region, wherein the active region includes first bottom SCH layer extending only in the output section and a second bottom SCH layer extending across both the input section and the output section.
7 . The multi-section semiconductor optical amplifier according to claim 6 , wherein the active region further includes a MQW layer on the second bottom SCH layer and a top SCH layer on the MQW layer.
8 . The multi-section semiconductor optical amplifier according to claim 1 , wherein the input section and the output section are formed by different active regions.
9 . The multi-section semiconductor optical amplifier according to claim 8 , further including a substrate, a buffer layer on the substrate, first and second active regions on the buffer layer and in the input section and the output section, respectively, and at least one cladding layer on the active regions.
10 . The multi-section semiconductor optical amplifier according to claim 9 , wherein the first active region includes a first bottom SCH layer and a first MQW layer on the first bottom SCH layer and a first top SCH layer on the first MQW layer and wherein the second active region includes a second bottom SCH layer and a second MQW layer on the second bottom SCH layer and a second top SCH layer on the second MQW layer, and wherein the first and second optical confinement factors Γ 1 , Γ 2 , are provided by different SCH thicknesses, different SCH compositions and/or different MQW layers.
11 . The multi-section semiconductor optical amplifier according to claim 1 , wherein the input section and the output section include separate confinement heterostructure (SCH) layers that are configured to provide the first optical confinement factor that is higher than the second optical confinement factor.
12 . The multi-section semiconductor optical amplifier according to claim 11 , wherein different thicknesses of the SCH layers provide the first optical confinement factor that is higher than the second optical confinement factor.
13 . The multi-section semiconductor optical amplifier according to claim 11 , wherein the SCH layers are not tapered.