US 12,267,106 B2
Frequency domain method and system for measuring modal bandwidth, chromatic dispersion, and skew of optical fibers
Xin Chen, Painted Post, NY (US); Kangmei Li, San Jose, CA (US); and Ming-Jun Li, Horseheads, NY (US)
Assigned to Corning Incorporated, Corning, NY (US)
Filed by CORNING INCORPORATED, Corning, NY (US)
Filed on Apr. 21, 2022, as Appl. No. 17/725,924.
Claims priority of provisional application 63/246,448, filed on Sep. 21, 2021.
Claims priority of provisional application 63/185,004, filed on May 6, 2021.
Prior Publication US 2022/0376786 A1, Nov. 24, 2022
Int. Cl. H04B 10/07 (2013.01); H04B 10/079 (2013.01); H04B 10/2581 (2013.01); H04B 10/54 (2013.01); H04B 10/077 (2013.01); H04B 10/25 (2013.01)
CPC H04B 10/07951 (2013.01) [H04B 10/2581 (2013.01); H04B 10/541 (2013.01); H04B 10/07 (2013.01); H04B 10/0775 (2013.01); H04B 10/25 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method comprising:
transmitting an intensity-modulated light through a mode conditioner to generate a mode-conditioned intensity-modulated light in one or a plurality of launch conditions;
transmitting the mode-conditioned intensity-modulated light at an operating wavelength through a multimode optical fiber under test (FUT) to excite a plurality of modes of the FUT;
converting with a photodetector the mode-conditioned intensity-modulated light transmitted through the FUT into an electrical signal;
measuring with a vector network analyzer, based on the electrical signal, a complex transfer function CTF(f) of the FUT;
obtaining an output pulse based on the measured complex transfer function CTF(f) from one or a plurality of launch conditions and an assumed input pulse using the following equation:
Pout(t)=custom character−1(CTF(f)*custom character(Pin(t)))
wherein Pout(t) is the output pulse, custom character−1(CTF(f)*custom character(Pin(t))) is the inverse Fourier transform of the function CTF(f)*custom character(Pin(t)), and custom character(Pin(t)) is the Fourier transform of the assumed input pulse; and
calculating with the vector network analyzer a modal bandwidth of the FUT based on Pout(t).