Patent ID: 9445165
Filing Date: 2016-09-13
CPC Classification: G02B,G02F,H04Q

Claim Text:
1. An optical directional coupler comprising: an input terminal configured to receive an input optical signal; a first coupler optically coupled to the input terminal, wherein the first coupler has a first coupling length, wherein the first coupler is configured to couple a first portion of the input optical signal to a first leg and a second portion of the input optical signal to a second leg, wherein the first leg is configured to phase shift the first portion of the input optical signal to produce a first phase shift signal, wherein the second leg is configured to phase shift the second portion of the input optical signal to produce a second phase shift signal, and wherein the first phase shift signal has a phase difference relative to the second phase shift signal; and a second coupler configured to receive the first phase shift signal and the second phase shift signal and to output a first output optical signal to a first output, wherein the second coupler has a second coupling length, wherein a crosstalk of the input optical signal to a second output is below −15 dB for both transverse electrical (TE) polarized light and transverse magnetic (TM) polarized over a wavelength range spanning at least 40 nm, and wherein the second coupling length is within 10% of twice the first coupling length.