Robert F. Tavlykaev

Novel linear integrated-optic modulator

In this paper, a novel scheme of interference type modulator is proposed which ensures enhancement of linearity of the modulation characteristic (MC) by adding sinusoidal MCs. These characteristics correspond to the waves that appeared as a result of multiple reflections from the waveguide faces.

Phase-bias tuning and extinction-ratio improvement of Mach-Zehnder interferometer

In order to reduce nonlinear distortions inserted in an analog optical system by an integrated-optic modulator (IOM) of interferometric type, it is necessary that the modulator phase bias be at the middle of the linear section of the modulation characteristic (MC). In this paper, a technique is presented that allows us to tune phase bias and extinction ratio in a wide range by adjusting a single-mode fiber (SMF) at the modulator input. The technique is based on excitation of the symmetric and asymmetric modes of the input Y-junction. The ratio of their amplitudes is tuned by changing coupling conditions (adjustment of the fiber) that results in tuning of phases and intensities of the waves in the interferometer arms. The technique can be applied for a Mach-Zehnder modulator of the conventional scheme (with a single-mode input waveguide section), but to strengthen the effect, it is useful to modify the modulator geometry.