DESIGN AND ANALYSIS OF TRENCH ASSISTED LARGE MODE AREA LEAKY CHANNEL WAVEGUIDE FOR HIGH-POWER APPLICATIONS

Abstract

Integrated-optic waveguide lasers have drawn considerable attention for their compactness and possibility of device integration. A lot of interest has been shown to increase the mode area of waveguide for applications in optical communication and high-power laser and amplifier. For waveguide laser and amplifier applications, it is preferable to use a waveguide that supports only one mode to avoid instability arising from intermodal dispersion and mode competition. A conventional single-mode waveguide has a small guiding core. The tight light confinement in such a waveguide can reduce the optical damage threshold of the waveguide and at the same time, give rise to significant nonlinear optical effects, which limit ultimately the power handling capability of the waveguide. A preferred structure for high-power applications should be one that has a large core and yet supports only a single mode. Here a novel cladding design in which the refractive index is uniform but the geometry is so designed that all the modes are leaky. Such a geometrically shaped cladding is highly dispersive and can also lead to singlemode operation over an extended range of wavelengths. Using properly chosen parameters, the waveguide can exhibit single-mode operation in the wavelength range 900–1600nm with a large core area.