We analyze the thermal stability of the power transmission efficiency and the extinction ratio in an asymmetric three-core silicon-on-insulator nonlinear directional coupler with variable Gaussian coupling coefficient. Because the refractive indices of Si and SiO2 materials are subject to temperature change, the effective refractive index of the nonlinear coupler varies correspondingly. When ratio (LC/b) and ΔT change, the relative transmission efficiency error (Δ) values and relative change of extinction ratio (η) values are obtained. It can be easily shown that variation of Δ and η are negligible under LC/b ≤ 1/2. Therefore, we can set LC/b ≤ 1/2 and ΔT ∈ [-100 K, 100 K] in order to make the power transmission efficiency and the extinction ratio work steadily. This is significant in guiding an actual nonlinear optical pulse switch fabrication.
Through the detail analysis of inter-satellites links in modern small satellite constellations, a new optical
filters-based four-channel wavelength division multiplexer was designed and fabricated. This WDM device
working at 0.85, 1.06, 1.31 and 1.55μm is designed to build an optical inter-satellites link, which provide two data
streams at 0.85 and 1.55μm, an inter-satellite tracking channel at 1.06μm, and an different orbit communication
channel at 1.31μm. Through experiments, we got the channel download efficiencies at 0.85, 1.06, 1.31 and 1.55μm
are 49.7%, 42.3%, 33.4% and 25.1% and the channel interval is 5mm. The features of small size and light weight
make this WDM device quite attractive for space borne applications and the big channel interval could also
accommodate the wavelength shifts due to Doppler Effect, temperature variations and radiation effects in space.