A Q-switched laser, which is pumped by at least one pump source (8), providing pulses. The laser comprises two mirrors (3,5) providing a laser cavity, in which a gain medium (2), a saturable absorber (4) and a controllable active modulator (6) is situated. Loss can be introduced in the modulator (6) by a control device (10). In a first phase, said control device (10) introduces loss in the active modulator, setting a threshold inversion density band to a level (B) high enough to be above the actual inversion density in the gain medium means. In a second phase, the control device lowers said loss instantly, which will lower the threshold inversion density band to a level (A) lower than the actual inversion density in order to activate emission of said Q-switched pulse.
An acousto-optic modulator includes a (100), (010) or (001) single crystal silicon acousto-optic interaction medium, and at least one transducer for emitting an acoustic wave attached to the single crystal. The transducer has a first electrode layer disposed on one side and a second electrode layer disposed on its other side. The transducer is aligned to the single crystal so that the direction of acoustic propagation in the silicon crystal is substantially along the (100), (010) or (001) direction. A q-switched laser includes a modulator according to the invention.
A laser includes a first optically reflective element; a second optically reflective element opposed to and aligned with the first optically reflective element to define a laser cavity having an optical axis; an optical pump source for injecting optical pump energy into the laser cavity along the optical axis; a solid-state dye gain element having a thin host in which a dye is dissolved that is interposed between said first and second optically reflective elements along the optical axis for transforming the optical pump energy into a resonant optical signal; and a cooling element in thermal contact with the solid-state dye gain element for absorbing heat energy from the solid-state dye gain element to control the temperature of the solid-state dye gain element.
A novel Q-switch device enables significant quality and value improvement for a Q-switched laser system by achieving a significant reduction of mode-beating noise during the pulsed output. The origin of mode-beating noise in a Q-switched laser is a result of high gain availability and amplification of competing standing-waves in formation, whose optical frequency is a product of natural selection via spatial hole burning in the gain medium. The novel Q-switch device employs an active, electro-optics or acousto-optics, Q-switch in combination with a saturable absorber device, to provide an optimized soft opening of the optical path and a controlled timing of a Q-switched laser. This novel combination offers larger modulation loss than otherwise possible with the active modulator alone, and it allows for higher gain build-up and energy extraction efficiency. Specifically, it will enable a low-voltage modulator (<100 V) for high gain (small-signal gain>10) and Q-switched operation at high repetition rate (>10 kHz). The combination is devised to slow down the signal build-up and to sweep the fundamental longitudinal mode frequency at least within the free spectral range of the resonator, such that it varies adiabatically during the Q-switched pulse formation. A laser geometry amenable to high gain and high power is proposed for use in conjunction with the proposed novel Q-switch device. The invention will enable the deployment of cost-effective Q-switched lasers operating in both single-longitudinal and single-transverse (TEM.sub.00) mode.
A diode pumped solid state laser for producing a high aspect ratio beam comprises a diode pumping array (1) on a diode array mount (3) and optical means for imaging a pump light beam onto a substantially asymmetrical spot with a smooth intensity profile. The pump light beam is pumping a laser medium (4). Both the pump and the lasing mode have strong asymmetries. In combination with the right choice of laser medium (4), this results in high power laser performance. The axis of the pump light beam is adjustable by a simple adjusting means (110) to a defined plane or direction relative to a mounting frame (111) of a diode array pumping device (103). The adjusting means (110) compensates small tolerances on mounting of the diode array (1) and/or at least one optical element (2). The adjusting means include at least one wedged window (127). Because of this adjustment the axis of the light beam lies in a defined plane relative to the mounting frame (111) of the pumping device (103). Therefore the diode array pumping device (103) of a laser is replaceable without any further adjustment.
A Laser arrangement (1) comprising a pump unit (2) containing a pumped laser crystal (3), and means, such as a saturable absorber (15), for passive mode-locking, wherein two separate, alternatively switchable resonator arms (11, 12) are provided, one resonator arm (11) of which, which is active in a pulse forming phase (21), comprises the saturable absorber (15), whereas the other resonator arm (12), which is active in an amplifying phase (22), is free from components that introduce losses.
