The ordinary negative changing refractive index for estimation of optical confinement factor

Abstract

The electro-optic effect is considered very important in optical communication systems. The small optical confinement factor is attributed to the weak overlap between the electric field and optical wave and hence the optical signal is not efficiently modulated. In this paper, the problem of the small optical confinement factor in the Mach–Zehnder modulator based on lithium niobate (LN) which is deeply studied. The data were analyzed through a proposed mathematical model to explain the relationship between the change in the ordinary negative refractive index and the confinement factor. The system is improved using a small length of the modulator arm as only 3 to 8 µm, low driving power of about 4 V/µm, a large change in the negative ordinary refractive index of about—0.2 × 10−7, and a compact optical modulator. This can reflect a strong optical confinement factor when the electric field is applied to the electrodes of the optical modulator.

Symmetric longitudinal Mach-Zehnder modulator using lithium niobate

“…The small length of the modulator arm leads to a large relative refractive index difference and lower applied voltage V leading to a higher quality of modulation. The best modulation is achieved when the length of the arm is 2-3mm, if compared with 10 mm, as in (18) [44], [45] (see Figures 3(a The refractive index difference depends on a low applied voltage and large wavelength, as in ( 19) and ( 20) [38]. The refractive index can be changed due to the control of phase modulation where the phase difference induces between arms.…”