Optical-waveguide hybrid coupler

Abstract

As a novel guided-wave passive device, the optical-waveguide hybrid coupler is proposed and its first known demonstration is reported. The proposed device consists of symmetric and nonsymmetric branching forks connected at a junction. An explanation of the working mechanism is presented. The feasibility of the device is confirmed by constructing and testing the hybrid coupler with an integrated Mach-Zehnder interferometer composed of a Y junction and phase shifters using a Ti-diffused LiNbO(3) waveguide.

All-Optical Wavelength-Selective Switch by Intensity Control in Cascaded Interferometers

“…However, waveguide-type wavelength-independent couplers have advantage from the viewpoint of integrating the switch elements. An alternative for improving wavelength dependence is to replace the directional couplers by asymmetric X-junction couplers (Izutsu et al, 1982;Burns & Milton, 1980;Hiura et al, 2007). The asymmetric X-junction coupler has basically no dependence on wavelength and helps to improve the wavelength dependency of the proposed switch (Kishikawa et al, 2009a;Kishikawa et al, 2009b).…”

Integrated-Optic Circuits for Recognition of Photonic Routing Labels

“…An asymmetric X-junction coupler shown in (d) is the device whose input and output are a symmetric Y-junction and an asymmetric Y-junction, respectively (Izutsu et al, 1982). When two waves are incident in phase, the output is obtained only at the wider-waveguide port.…”

“…asymmetric X-junction coupler (Izutsu et al, 1982;Burns & Milton, 1975;Burns & Milton, 1980), and time gates. The asymmetric X-junction coupler provides a function of wave coupling according to the phase relation between the two incident waves.…”

LiNbO3 optical switch using asymmetric X-junction waveguide for broadband optical network node

“…As for the LiNbO 3 optical switch, a directional coupler is used as a 3-dB coupler and the splitting ratio is dependent on a wavelength of the incident light. On the other hand, an asymmetric X-junction configuration was proposed by Izutsu et al [1,2] It has advantages of easy fabrication and low wavelength independence compared to a directional coupler. They fabricated the optical switch using asymmetric Xjunction and the extinction ratio of the switch was 15 dB; which might be limited by the excess loss and unexpected mode conversion at the junction.…”

“…They fabricated the optical switch using asymmetric Xjunction and the extinction ratio of the switch was 15 dB; which might be limited by the excess loss and unexpected mode conversion at the junction. [1] To obtain broadband characteristics and reduce device size, X-junctions were used for other types of optical switches including polymeric waveguide switches [3,4], a GaAs based switch [5] and an all-optical switch [6].…”