A Y-fed directional coupler modulator with a highly linear transfer curve

• Published in: IEEE photonics technology letters Vol. 12; no. 11; pp. 1474 - 1476
• Main Authors: Kishino, T., Tavlykaev, R.F., Ramaswamy, R.V.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2000; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Devices; Directional couplers; Electrodes; Fabrication; High speed optical techniques; Integrated optics; Linearity; Modulation; Modulators; Optical devices; Optical distortion; Optical modulation; Optical sensors; Polarity; Tolerances
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/68.887684

We demonstrated a linearized Y-fed directional coupler modulator in Z-cut LiNbO/sub 3/. The proof-of-concept device employed two electrode sections of opposite polarity whose lengths were chosen based on the results of our previous theoretical modeling. A highly linear modulation characteristic and improved tolerance to fabrication errors were achieved with a simple design, in excellent agreement with the theory. The linearity exceeded 90% over a wavelength range of 45 nm, centered around 1530 nm, with a maximum linearity of 97% at 1510 nm and a maximum modulation depth of 98%. By comparison, the linearity of conventional modulators is typically around 70%. Thus the device was proven to have a high linearity with a wide usable spectral range and relaxed fabrication tolerances.