| Popis: |
The irreversible gigantic modification (IGM) occurs in semiconductors under simultaneous action of strongly polar liquid, acceptors dissolved in it, and optical radiation in the region of fundamental absorption. The IGM phenomenon is found by the authors in the III-V and II-VI compound semiconductors. During the IGM process the reflection and transmission coefficients are gradually varying in a modified near-surface semiconductor region. This enables to reduce controllably the real part of the complex refractive index in a near-surface semiconductor region (maximum down to 0.8), vary its chemical composition (by impurity redistribution) and the luminescence spectrum. After IGM the modified semiconductor region gains an ability to modulate a light beam with one wavelength (in the region of semiconductor transparency) by a light beam with another wavelength (in the region of fundamental absorption). The modulating, action propagates in a modified semiconductor with the velocity of 100 ms/mm. Increasing a distance between the controlling and controlled beams enables to implement a time delay between signals. The time delay up to 1.7 second has been achieved experimentally. We have used the IGM phenomenon to fabricate elements and devices of the integrated semiconductor optics (input/output diffraction gratings, channel waveguides and input horns, directional optical couplers, ohmic contact areas). The IGM phenomenon enables to make antireflective optical elements (input and output butts of infrared lightguides, lenses, prisms). |
