Non-reflective/reflective phase transition optical modulator

#1. Field of the Invention

#The invention disclosed herein relates to modulators of luminous energy typified by that generated in lasers, and particularly those modulators fabricated with oxide compounds which undergo transitions between metallic and non-metallic states in response to external stimuli.

#2. Description of the Prior Art

#FIGS. 1a and 1b schematically show the respective layouts of a conventional Q-switched laser and a conventional cavity dumped laser.

#FIG. 2a schematically depicts a single crystal structure fabricated from one of the oxide compounds in the group.

#FIG. 2b is a schematic of another embodiment, wherein a thin film of the compound is sandwiched between transparent materials.

#FIGS. 1a and 1b schematically represent two of the many conventional laser configurations, these two being known in the parlance of the art as a Q-switched laser and a cavity dumped laser, respectively. In the Q-switched laser of FIG. 1a rotating mirror 1 is synchronized with the transmission of luminous energy 3 from flash lamp type pump 2 into gain medium 4 of the laser's resonating cavity. When mirror 1 rotates into alignment, lasing commences. Output coupling mirror 6 normally transmits about 30% of the incident luminous energy, reflecting the remainder back into gain medium 4. Thereby, laser output 7 consists of pulses having a repetition rate corresponding to the rotation rate of mirror 1.

#The cavity dumped configuration in FIG. 1b extracts a laser pulse by deflecting the luminous energy beam. As with the Q-switched configuration pump 2 supplies luminous energy 3 to gain medium 4 of the laser resonating cavity. At one end of gain medium 4 is stationary mirror 8, while the luminous path from the other end of gain medium 4 communicates with mirror 9, acousto-optic modulator 11, mirror 12, and at times prism 13. Since the configuration in FIG. 1b is well known, it need only be noted that stimulation of acousto-optic modulator 11 alters the path of incident luminous energy onto the path defined by reference line 16. Without stimulation, luminous energy passing through acousto-optic modulator 11 follows the path defined by dashed line 14, effectively being retroreflective as to gain medium 4.

#The central feature of the invention is a utilization of oxide compounds from a defined group to directly control the luminous energy leaving the resonating cavity of a laser. When stimulated, compounds from this group respond by undergoing a transition between metallic and non-metallic states, which correspond to reflection or transmission of the incident luminous energy.