PROPAGATION CHARACTERISTICS OF LEAKY OPTICAL WAVEGUIDES

Abstract

Leaky Waveguides are useful for high power lasers and amplifiers. High power waveguide lasers require a waveguide that supports only one mode to avoid instability arising from intermodal dispersion and mode competition. A conventional single-mode waveguide however, has a small guiding core and has very tight light confinement. This can reduce the optical damage threshold of the waveguide and can also give rise to significant nonlinear optical effects, which ultimately limit the power handling capability of the waveguide. So a preferred structure for high-power applications should be one that has a large core and yet supports only a single mode; this can be achieved by a leaky waveguide structure in which all the higher order modes are leaked out. In the present work we have studied the resonant leaky optical waveguide to have large-core single mode operation and to have tailored dispersion. The waveguide is characterized by a large inner core and a leaky outer core. Suitable design parameters can enable the coupling of power from guiding core to high leaky outer core. Because of this coupling effect the differential leakage loss of the first two modes becomes very high, so that the higher order modes are leaked out very easily. We have also used this resonant waveguide as a dispersion compensator for that chose the waveguide parameters such that the waveguide supports only the fundamental. This fundamental mode is resonantly coupled to the mode of the outer core. The resonance effect in the waveguide causes the generation of supermodes . which plays an important role in the dispersion compensation. We have shown that large negative dispersion can be achieved in one of the supermodes of the structure. The proposed waveguide can be easily formed in silica and should be useful for dispersion compensation in WDM application.