METHOD FOR ADJUSTING INITIAL OPERATION POINT OF WAVEGUIDE TYPE OPTICAL ELEMENT

• Main Authors: ICHIKAWA JUNICHIRO, NAGATA HIROTOSHI, KIUCHI KAZUMASA
• Format: Patent
• Language: English
• Published: 16.06.1995
• Edition: 6
• 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; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

PURPOSE:To make it possible to adjust the initial operation point of an optical element without using a DC electric field for control by applying a DC voltage from the outside on a waveguide type optical element on which external electric field has not been impressed, thereby irreversibly changing the optical modulation characteristics thereof. CONSTITUTION:The material characteristics of the optical element right after production are such that, in the state of (a), the peak value of a modulation waveform exists nearly at a zero voltage and a change of the corresponding light intensity is too small to detect a slight change of the external electric field as a change of light output intensity, and, the light output intensity changes in a decreasing direction even if the external electric field changes. The DC voltage is, thereupon, applied on this optical element and the element is left as it is. A drift having a hysteresis arises and the initial operation point (phase at the zero voltage) of the optical element moves nearly to a mid-point of the peak and valley of the modulation waveform if the voltage applied thereon is released after the application thereon and the element is left as it is (b). The large light intensity change is obtd. dependently upon the slight change of the external electric field in such state and, therefore, the initial state preferable as an electric field sensor is obtd.