US 11,885,677 B2
High-performance on-chip spectrometers and spectrum analyzers
Derek Kita, Cambridge, MA (US); Carlos Andres Rios Ocampo, Cambridge, MA (US); and Juejun Hu, Newton, MA (US)
Assigned to Massachusetts Institute of Technology, Cambridge, MA (US)
Filed by Massachusetts Institute of Technology, Cambridge, MA (US)
Filed on Apr. 12, 2021, as Appl. No. 17/227,440.
Application 17/227,440 is a continuation of application No. 16/710,621, filed on Dec. 11, 2019, granted, now 10,983,003.
Claims priority of provisional application 62/803,993, filed on Feb. 11, 2019.
Prior Publication US 2021/0239526 A1, Aug. 5, 2021
Int. Cl. G01J 3/02 (2006.01); G01J 3/45 (2006.01); G01J 3/453 (2006.01); G02F 1/21 (2006.01)
CPC G01J 3/0256 (2013.01) [G01J 3/0205 (2013.01); G01J 3/0213 (2013.01); G01J 3/45 (2013.01); G01J 3/4531 (2013.01); G01J 3/4532 (2013.01); G02F 1/212 (2021.01)] 18 Claims
OG exemplary drawing
 
1. A method of operating a spectrometer, the method comprising:
splitting incident light into a first portion and a second portion;
transmitting the first portion through at least one delay stage switchable between a first waveguide having a first optical path length and a second waveguide have a second optical path length different than the first optical path length;
transmitting the second portion through a reference waveguide;
attenuating at least one of the first portion or the second portion to compensate for loss imbalance between the at least one delay stage and the reference waveguide;
detecting interference between the first portion with the second portion; and
determining a spectrum of the incident light based on the interference of the first portion and the second portion,
wherein attenuating the first portion comprises modulating a relative phase between the first portion and the second portion such that the interference of the first portion with the second portion has a null at a desired frequency.