Coherently Coupled Optical Waveguide

Introduction Paper Review Principle of Operation Experiences and Results Summery ReferencesOutline

IntroductionMotivation:Optical bending waveguide are used to change the direction of light propagation in many integrated optical devices such as MZ and directional couplers. In order to reduce the device area and increase the packing density, we must to find bend structures with large bend angles and low loss.Structure: Curved optical waveguide; Conventional bend waveguide; Etched-wall bend waveguide; Coupler bend waveguide; Prism waveguide. Principle of coupler bend waveguide: Coupled-bend transmission can be an oscillatory function of the interconnection length L due to interference between the guided and radiation modes.Material:Ti ; Ni ; Zn and Ni

Introduction Paper Review Principle of Operation Experiences and Results Summery References

Conventional Bend WaveguideP0: output powerPi: input power0: radiation and absorb parameterLo: distance of optical beam propagating in waveguide T: power combine parameter( )

Etched-wall Bend Waveguide Advantage: power loss is lower than convention bend waveguide.Disadvantage: As larger than 20, power loss will be higher and make this bending waveguide not to have the ability of light propagation.Wave front in the part is speeded up to make bending easier and reduce the power loss.

Coupler Bend Waveguide Advantage: power loss is lower with suitable coherent length.d

Introduction Paper Review Principle of Operation Experiences and Results Summery References

Principle of Coherent Coupler I 123

Principle of Coherent Coupler II

Principle of Coherent Coupler III The equation shows that the coupled-bend transmission can be an oscillatory function of the interconnection length L due to interference between the guided and radiation modes.Guided modeRadiation mode

Principle of Coherent Coupler V

Principle of Coherent Coupler VI

Introduction Paper Review Principle of Operation Experiences and Results Summery References

Coherently Coupler Bend SECTION LENGTH, L( m )

Coherently Coupler Bend NUMBER OF SECTIONS ( N )N = 2

Coherently Coupler Bend (a)standard structure(b)new structure

Transmitted Power with Total Bending Angle

Transmitted Power with Launching Wavelength

Summery

The transmission function of the coupler bend waveguide depends on the interference of guided mode and radiation mode in the interconnection length L.

We study the principle of coupler bend waveguide which is better than conventional bend and etched-wall bend waveguide in being a suitable bending structure with large bend angles and low loss.

Other new structures include prism and new structure couple bend waveguide.

References

L. M. Johnson and F. J. Leonberger, Low-loss LiNbO3 waveguide bends with coherent coupling, Optics Letters, Vol. 8, No. 2, Feb. 1983.

L. M. Johnson and D. Yap, Theoretical analysis of coherently coupled optical waveguide bends, Applied Optics, Vol. 23, No.17, 1 Sep.1984.

, An Investigation of integrated optical waveguide bends,

, Coherent-coupling-based wide-angle bending optical waveguide design and fabrication,