Universal method to determine the thermo-optic coefficient of optical waveguide layer materials using a dual slab waveguide

Abstract

A dual slab waveguide device method for determining the thermo-optic coefficient of waveguide layer materials is demonstrated. Temperature change-induced optical path length imbalance between two single slab waveguide modes provides the primary mechanism for detection. The waveguide mode output field phase change differences are encoded in shifts in the far field interference pattern. To illustrate the method, the thermo-optic coefficients of two In1−xGaxAsyP1−y quaternary alloys, 1.3Q and 1.15Q, are measured at a wavelength of 1.55μm and at a center temperature of 25.2°C. Their ratio is in excellent agreement with previous work, in accordance with optical dispersion models.

Temperature effects in metal-clad semiconductor nanolasers

“…The thermo-optic coefficient (TOC), dn r /dT, in InGaAs and InGaAsP is on the order of 10 -4 RIU/K [46], where RIU refers to refractive index units. This means that a change in temperature by 100 K only changes the refractive index by a factor of 0.01.…”

“…As an example, we simulate a nanolaser geometry similar to that shown in Figure 3A, but with a gain radius of 250 nm and optimal shield thickness of 100 nm, using the commercial software COMSOL Multiphysics' EM module. In Figure 3D, the resonant wavelengths of the first six cavity modes are plotted as a function of temperature, for both a positive [46] and effectively negative TOC [48,49] of the gain medium. The latter corresponds to the empirical observations of Massum et al [48] and Ramoo et al [49].…”