US 12,316,074 B2
Optical transmitter
Takahiko Shindo, Musashino (JP); Meishin Chin, Musashino (JP); and Shigeru Kanazawa, Musashino (JP)
Assigned to Nippon Telegraph and Telephone Corporation, Tokyo (JP)
Appl. No. 17/760,844
Filed by Nippon Telegraph and Telephone Corporation, Tokyo (JP)
PCT Filed Sep. 26, 2019, PCT No. PCT/JP2019/037958
§ 371(c)(1), (2) Date Mar. 16, 2022,
PCT Pub. No. WO2021/059449, PCT Pub. Date Apr. 1, 2021.
Prior Publication US 2022/0352692 A1, Nov. 3, 2022
Int. Cl. H01S 5/12 (2021.01); H01S 5/026 (2006.01); H01S 5/06 (2006.01); H01S 5/10 (2021.01); H01S 5/34 (2006.01)
CPC H01S 5/12 (2013.01) [H01S 5/026 (2013.01); H01S 5/0265 (2013.01); H01S 5/0601 (2013.01); H01S 5/10 (2013.01); H01S 5/1014 (2013.01); H01S 5/34 (2013.01)] 4 Claims
OG exemplary drawing
 
1. An optical transmitter comprising, on a substrate,
a distributed feedback (DFB) laser including an active region with a multi quantum well;
an electro-absorption (EA) modulator including an absorption region with a multi quantum well having a composition different from the multi quantum well of the DFB laser, and configured to modulate light emitted from the DFB laser; and
a semiconductor optical amplifier (SOA) having an active region with an identical composition as the active region of the DFB laser and configured to amplify signal light from the EA modulator,
wherein the DFB laser, the EA modulator, and the SOA are monolithically integrated on the substrate, and
wherein a width of a core layer in a cross section perpendicular to an optical waveguide direction of the SOA is smaller than a width of a core layer in the cross section perpendicular to the optical waveguide direction of the DFB laser.