US 12,326,642 B2
Wavelength filter and laser apparatus
Yukie Iga, Tachikawa (JP); Hirotomo Izumi, Kawasaki (JP); Kazumasa Takabayashi, Atsugi (JP); and Suguru Akiyama, Tsukuba (JP)
Assigned to FUJITSU OPTICAL COMPONENTS LIMITED, Kawasaki (JP)
Filed by Fujitsu Optical Components Limited, Kawasaki (JP)
Filed on Jun. 21, 2022, as Appl. No. 17/845,365.
Claims priority of application No. 2021-122248 (JP), filed on Jul. 27, 2021.
Prior Publication US 2023/0035193 A1, Feb. 2, 2023
Int. Cl. G02F 1/21 (2006.01); G02F 1/225 (2006.01); H01S 5/00 (2006.01); H01S 5/50 (2006.01)
CPC G02F 1/212 (2021.01) [G02F 1/225 (2013.01); H01S 5/005 (2013.01); G02F 2203/055 (2013.01); H01S 5/50 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A wavelength filter comprising:
a first filter circuit
that has a passband that is obtained from a vernier effect by connecting, in series, a plurality of ring resonators each having a different transmission wavelength interval and that is within a gain band of an optical amplifier, and
that passes, from the gain band, light at a selected wavelength and light that has a wavelength in a recursive mode and that is produced on a short wavelength side or a long wavelength side of the selected wavelength; and
a second filter circuit that is connected to the first filter circuit in series and that suppresses the light at the wavelength in the recursive mode from the light passing through the first filter circuit.