OPTICAL ELEMENT, OPTICAL CONTROL METHOD AND APPARATUS USING THE OPTICAL ELEMENT, AND METHOD OF MANUFACTURING THE OPTICAL ELEMENT

摘要

An optical element, an optical control method and an optical control apparatus, wherein use is made of a low-power laser beam as a control beam to yield a light response of sufficient magnitude and speed. A control beam is projected from a light source (1), while a signal beam is from a light source (2). The control beam and the signal beam are converged by a condenser lens (7) and thrown onto an optical element (8). These beams pass through a light receiving lens (9) and a wavelength selection filter (20), and only the signal beam is detected with a photodetector (22). By turning the control beam on and off, a thermal lens is reversibly formed in the optical element, realizing the modulation of the signal beam intensity. The optical element may be formed in a laminated structure comprising, for example, a heat transfer layer, a heat retaining layer, and a heat transfer layer, and the thickness of the light absorbing layer is adjusted so as not to exceed two times the confocal distance of the converged control beam, thereby providing a light response of sufficient magnitude and speed by the use of a low-power laser beam as a control beam.