Silicon-photonics-based semiconductor optical amplifier with N-doped active layer

A tunable laser module comprising:

• a laser configured to generate laser light, the laser comprising a reflective semiconductor optical amplifier (RSOA), the RSOA configured to reflect and emit the laser light, the RSOA comprising
• a first front facet having an anti-reflective coating, a reflectance less than or equal to 0.005%, and configured to output the laser light,
• a first back facet having a reflective coating, a reflectance greater than 90%, and configured to reflect the laser light to the first front facet, and
• a first gain medium i) extending from the first front facet to the first back facet, ii) in combination with the first front facet and the first back facet exhibiting a first mirror loss to amplify the laser light for data communication, and iii) comprising a multilayer structure, the first mirror loss being 45-100 cm−1 in accordance with αm1=(½L)ln{1/(Rf×Rb)}, where Rf is the reflectance of the first front facet and Rb is the reflectance of the first back facet, the multilayer structure comprising
• a first P-layer,
• a first N-layer,
• a first N-doped active layer disposed between the first P-layer and the first N-layer and having undoped well layers, and
• first N-doped barrier layers alternating with the undoped well layers between the first P-layer and the first N-layer;
• and
• a passthrough semiconductor optical amplifier (SOA) separate from the laser and configured to receive and amplify the laser light emitted from the RSOA, the passthrough SOA comprising
• a second front facet having an anti-reflective coating and a reflectance less than or equal to 0.005%,
• a second back facet having an anti-reflective coatingnd a reflectance less than or equal to 0.005%, the anti-reflective coating of the second front facet and the anti-reflective coating of the second back facet allowing the laser light to pass through the passthrough SOA once and be amplified by the passthrough SOA, and
• a second gain medium i) extending from the second front facet to the second back facet, ii) in combination with the second front facet and the second back facet exhibiting a second mirror loss to further amplify the laser light for data communication, and iii) comprising a multilayer structure, the second mirror loss being between 40 and 200 cm−1 in accordance with αm2=(½L)ln{1/(Rf2×Rb2)}, where Rf2 is a reflectance of the second front facet and Rb2 is a reflectance of the second back facet, and the multilayer structure of the second gain medium comprising
• a second P-layer,
• a second N-layer,
• a second N-doped active layer disposed between the second P-layer and the second N--layer and having undoped well layers, and
• second N-doped barrier layers alternating with the undoped well layers between the second P-layer and the second N-layer.