Title :
Photogalvanic pulsator
Author :
Kukhtarev, N. ; Kukhtareva, T. ; Bayssie, M. ; Hudson, Teresa ; Friday, W.A. ; Shkolnikov, I. ; Abdeldayem, H. ; Penn, B. ; Frazier, D.
Author_Institution :
Alabama A&M Univ., Normal, AL, USA
Abstract :
Summary form only given. We have observed regenerative photoinduced pulsations of optical and radio-frequency signals, generated by CW laser irradiation from Ar-ion laser in LiNbO/sub 3/:Fe. Pulsating optical scattering from the crystal has a distinct spatial structure in the form of expanding circular rings or bright crosses. Simultaneously, strong electromagnetic signals (EMS) are emitted from the crystal with bandwidth of about 1 GHz at 10% signal level. EMS was detected by an antenna-type electrode and analyzed by oscilloscope. We also have observed temporal modulation of the polarization state of cross-propagated signal beams at /spl lambda/ = 514 and 647 nm, synchronized with the EMS pulsations. Our explanation of the observed pulsations is based on self-organization of the photoinduced scattering into an array of reflection-type holographic gratings. Backscattering light waves combine with the forward pump wave, resulting in recording of the set of reflection electric-field gratings. The photogalvanic effect contributes to grating recording and creates a strong electric field along the optical axis about 50 kV/cm, which changes Bragg conditions for the holographic light scattering. This strong field also causes modulation of the probe signal laser beam due to modulation of birefringence by the electro-optic effect. As a result, strong space-charge waves are generated in the crystal, leading to the observed EMS picked-up by the antenna electrode.
Keywords :
backscatter; electro-optical effects; holographic gratings; iron; light scattering; lithium compounds; microwave photonics; photovoltaic effects; space charge; 1 GHz; 514 nm; 647 nm; Ar; Bragg conditions; CW Ar-ion laser irradiation; LiNbO/sub 3/:Fe; antenna-type electrode; backscattering light waves; bandwidth; birefringence modulation; bright crosses; cross-propagated signal beams; electro-optic effect; expanding circular rings; forward pump wave; grating recording; holographic light scattering; optical axis; oscilloscope; photogalvanic effect; photogalvanic pulsator; photoinduced scattering; polarization state; probe signal laser beam; pulsating electromagnetic signals; pulsating optical scattering; radio-frequency signals; reflection electric-field gratings; reflection-type holographic grating array; regenerative photoinduced pulsations; self-organization; spatial structure; strong electric field; strong space-charge waves; temporal modulation; Electrodes; Holographic optical components; Holography; Light scattering; Medical services; Optical modulation; Optical pumping; Optical recording; Optical scattering; Ring lasers;
Conference_Titel :
Lasers and Electro-Optics, 2002. CLEO '02. Technical Digest. Summaries of Papers Presented at the
Conference_Location :
Long Beach, CA, USA
Print_ISBN :
1-55752-706-7
DOI :
10.1109/CLEO.2002.1034042