Optical modulating apparatus having bias controller and bias control method

• Main Authors: LEE GYU-WOONG, OH YUN-JE, HWANG SEONG-TAEK
• Format: Patent
• Language: English
• Published: 04.04.2006
• Subjects: DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; GYROSCOPIC INSTRUMENTS; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; MEASURING DISTANCES, LEVELS OR BEARINGS; NAVIGATION; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICAL LOGIC ELEMENTS; OPTICS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY; PHYSICS; SURVEYING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; TESTING

Disclosed are an optical modulating apparatus having a bias controller and a bias control method using the same, which can automatically perform a bias adjust so as to keep the optical output characteristic of an optical modulator constant. The optical modulating apparatus includes an optical modulator to modulate an optical carrier using a bias signal; and a bias controller to adjust the bias signal of the optical modulator by detecting a second harmonic signal of the modulated optical signal, setting a minimum point of the second harmonic signal as a reference bias voltage, and then comparing a magnitude of the second harmonic signal that changes according to an external environment with a magnitude of a signal generated from the reference bias voltage.