High efficiency CW green-pumped alexandrite lasers

Abstract

High power, CW and pulsed alexandrite lasers were produced by pumping the laser rod with high quality diode pumped 532 nm laser sources. This pumping architecture provides stable performance with output power > 1.4 W at 767nm in the free running mode and 0.78W at 1000 Hz. An output of 80 mW at 375.5 nm was achieved at 500 Hz. This approach holds promise for the production of a scalable diode-pumped, tunable alexandrite laser systems operating in the near infrared (750 nm), and the ultraviolet (375 and 250 nm) spectral regions.

High power continuous-wave Alexandrite laser with green pump

“…They are a bit lower than the previously reported 31% slope efficiency and 32% optical-to-optical efficiency in [11] shown as a dashed line in figure 4. This can be explained by a higher level of intracavity loss due to the increased number of mirrors in our cavity (only one in [11] which used a semi-monolithic cavity) as well as due to possible slight misalignment of the used crystal from the perfect condition of Brewster angle of incidence. The laser spectrum at the maximum output power in free running mode is illustrated in figure 5.…”

“…An alternative approach to improving output power and beam quality is to use high power diffraction limited green pump sources at 532 nm that are widely used with Ti:Sapphire lasers. In fact, the Alexandrite laser with 1.4 W of output power and wavelength tunability of 50 nm has already been demonstrated [11]. Among all of these pumping methods the green pump has the highest brightness, can achieve output powers of >20 W and is commercially available.…”

Tapered diode-pumped continuous-wave alexandrite laser

“…Results obtained in this work have also been listed at the end of the table (marked with "b"). As mentioned earlier, the broad emission bands of alexandrite in the visible enables use of a variety of pump sources, including flash lamps [45], Hg and Xe lamps [25,46,66], sunlight [50], and the second harmonic of Nd-based systems [48,49]. Using these pump sources, tens of Watts of cw output power have been obtained from alexandrite lasers.…”

“…Diverse excitation bands (broadband 4 T 1∕2 excitations and narrowband R 1∕2 excitations) allow different pump options for alexandrite. Flashlamps [45], Xe/Hg arc lamps [25,46], krypton ion lasers (647 nm) [47], dye lasers (615-680 nm) [36], frequencydoubled neodymium lasers around 530 nm [48,49], and even sunlight [50] have been used for pumping cw alexandrite lasers. With lamp pumping, output powers as high as 60 W could be obtained.…”

Alexandrite spectroscopic and laser characteristic investigation within a 78–400 K temperature range

“…Direct laser diode pumping offers the potential of an order-of-magnitude higher efficiency compared with welldeveloped but flash-lamp pumped and inefficient alexandrite laser systems in the 1980s [2,6]. Efficient alexandrite laser emission has been demonstrated under red [8,9] and green [10,11] laser diode pumping. In this contribution, an InGaN blue laser diode pumped alexandrite laser is reported, for the first time to our best knowledge.…”