Ahmed Zabana was an Algerian militant who participated in the outbreak of the Algerian War. He was executed by guillotine on June 1956, in Algiers. Zabana was born in 1926 in Saint-Lucien; the youngest of nine children, he was a member of the Algerian Muslim Scouts, which inspired nationalist feeling in him. He joined the Movement for the Triumph of Democratic Liberties in 1950, he became a member of the military wing of a pro-independence secret society, participated in a mail operation in Oran in 1950. He was arrested and spent three years in prison and an additional three years in exile. After the dissolution of the Revolutionary Committee of Unity and Action on 5 July 1954, Zabana was commissioned by Larbi Ben M'hidi to prepare for the revolution by obtaining weapons and personnel. Zabana's tasks were to structure revolutionary forces and train them, to visit strategic locations to choose places that could be made centers of revolution. Zabana succeeded in forming revolutionary cadres in Zahana, Oran, Aïn Témouchent, Hammam Bou Hadjar, Hassi El Ghella, Chaabet El Ham. he ordered the men of the cadres to gather subscriptions for buying weapons and ammunition.
With Abdulmalek Ramadan, Zabana supervised the military training of the cadres. At a meeting on October 30th, 1954, chaired by Ben M'hidi, the organizers of the revolution determined that it would begin with a series of attacks on the night of November 1st; the following day, October 31st, Zabana met with his units and assigned specific targets as well as a rendezvous point on Jabal al-Qada. On November 1st, 1954, Zabana led a successful operation in Lamarda. After carrying out the offensive operations against the agreed French objectives, Zabana met with the leaders and members of the operational teams to assess them and plan what should be done in the coming stages. Zabana was captured in the Battle of Gar Bouklida on November 1954, in which he was wounded, he was taken to a hospital and to prison. On April 21st, 1955 Zabana was sentenced to death. On May 3rd, 1955, he was transferred to the Serkadji Prison in Algiers, he was executed on 19 June 1956. The Ahmed Zabana National Museum and Ahmed Zabana Stadium in Oran are named after him.
In 2012, the Algerian film director Saïd Ould-Khelifa launched a biographical film Zabana! with the lead role of Zabana played by Imad Benchenni. Commemoration of Ahmed Zabana - algerie-plus.com
Photodarkening is an optical effect observed in the interaction of laser radiation with amorphous media in optical fibers. Until now, such creation of color centers was reported only in glass fibers. Photodarkening limits the density of excitations in fiber amplifiers; the experimental results suggest that operating at a saturated regime helps to reduce photodarkening. One could expect the term photodarkening to refer to any process when any object becomes non-transparent due to illumination with light. Formally, the darkening of the photo-emulsion could be considered as photodarkening. However, recent papers use this term meaning reversible creation of absorbing color centers in optical fibers. One may expect. According to the Encyclopedia of Laser Physics and Technology, photodarkening is the effect that the optical losses in a medium can grow when the medium is irradiated with light at certain wavelengths. We may define photodarkening as reversible creation of absorption centers in optical media at the illumination with light.
The inverse of the timescale at which photodarkening occurs can be interpreted as photodarkening rate Usually, photodarkening is attributed to creation of color centers due to resonant interaction of electromagnetic field with an active medium The phenomenon, similar to photodarkening in fibers, was observed in chunks of Yb-doped ceramics and crystals. At the high concentration of excitations, the absorption jumps up, causing the avalanche of the broadband luminescence. Increase of absorption can be caused by formation of color centers by electrons in the conduction band, created by several neighboring excited ions.. This explains. In the experiments, the thermal effects are important. Recent work pointed out the role of thulium contamination. Through laser pump and signal absorption, energy transfer from ytterbium. Although the actual mechanism of photodarkening is still unknown, a reliable setup to test the photodarkening properties of different types of fibers has been reported