US 11,909,171 B2
Laser-integrated balance detection for self-mixing interferometry
Tong Chen, Fremont, CA (US); Fei Tan, San Jose, CA (US); and Mingzhou Jin, Campbell, CA (US)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Mar. 31, 2021, as Appl. No. 17/219,744.
Prior Publication US 2022/0320820 A1, Oct. 6, 2022
Int. Cl. G01C 3/08 (2006.01); H01S 5/026 (2006.01); H01L 31/0352 (2006.01); H01S 5/183 (2006.01); H01S 5/34 (2006.01); G01S 7/481 (2006.01); G01S 7/4912 (2020.01); G01S 7/4913 (2020.01)
CPC H01S 5/026 (2013.01) [G01S 7/4812 (2013.01); G01S 7/4913 (2013.01); G01S 7/4916 (2013.01); G01S 7/4917 (2013.01); H01L 31/035236 (2013.01); H01S 5/18361 (2013.01); H01S 5/34 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An optical sensor system, comprising:
a semiconductor substrate;
a set of epitaxial layers formed on the semiconductor substrate and defining,
a semiconductor laser having a first multiple quantum well (MQW) structure, wherein electromagnetic radiation is generated by the first MQW structure, emitted from the first MQW structure, and self-mixed with a portion of the emitted electromagnetic radiation that is returned to the first MQW structure;
a second MQW structure, positioned on a first side of the first MQW structure and operable to generate a first photocurrent responsive to detecting a first emission of the semiconductor laser; and
a third MQW structure, positioned on a second side of the first MQW structure and operable to generate a second photocurrent responsive to detecting a second emission of the semiconductor laser, the second side opposite the first side; and
a circuit configured to generate a self-mixing interferometry (SMI) signal by combining the first photocurrent and the second photocurrent.