Improved 2nd harmonic rise-time in a thermal-lens-dominated extended-cavity micro-laser
Many commercially available compact, micro-cavity diode-pumped solid-state lasers achieve a stable resonator condition following the formation of an intra-cavity thermal lens. Typically, this thermal lens forms as a result of localized thermal expansion in the host material due to the very high optical power of the infrared pump beam. Additionally, most common DPSS host media, such as Nd:YAG and Nd:YVO4 exhibit high dn/dT, change in refractive index with temperature. Thermal lens formation time dominates stable resonator establishment and, thus, the rise-time of the intra-cavity-generated visible second-harmonic output light. Thermal lens formation time may range from 10's of microseconds to several milliseconds, depending on pump power, the host material dn/dT, and the volume and length of the host material. This paper describes a unique approach that improves the second-harmonic rise-time - and, thus, the modulation bandwidth - for high-power VECSELs by several orders of magnitude. This approach, while typically used in some laser systems for other purposes, allows direct modulation of high-power VECSELs to greater than 100 megahertz with second-harmonic rise-time of a few nanoseconds.
Laser resonators and beam propagation : fundamentals, advanced concepts and applications
The Electromagnetic Field.- Geometrical Optics.- Wave Optics.- Polarization.- Basic Properties of Optical Resonators.- The Fabry Perot Resonator.- Passive Open Resonators.- Stable Resonators.- Resonators on the Stability Limits.- Unstable Resonators.- Resonators with Internal Optical Elements.- Open Resonators with Gain.- The Active Medium.- Output Power of Laser Resonators.- Influence of Gain on Mode Structure and Loss.- Q-switched Laser Resonators.- Resonators with Variable Internal Lenses.- Resonators with Several Active Media.- Misalignment Sensitivity of the Output Power.- Resonators with Internal Nonlinear Elements.- Special Resonator Concepts.- Prism Resonators.- Fourier Transform Resonators.- Hybrid Resonators.- Resonators for Annular Gain Media.- Ring Resonators.- Single Mode Resonators.- Measurement Techniques.- Measurement of Laser Head Parameters.- Measurement of Laser Beam Parameters.
High-power high-brightness 980-nm lasers based on the extended cavity surface emitting lasers concept
We describe design and performance of novel, electrically pumped, vertical compound cavity semiconductor lasers emitting at 980 nm. The laser combines a vertical cavity semiconductor laser with a partially reflecting output coupler and an external cavity for mode control. The concept is scalable and has been demonstrated in monolithic low power (few miliwatts) devices all the way to high power extended cavity devices which generate over 950 mW CW multimode power and 0.5 W CW power in a TEM00 mode, the latter with 90% coupling efficiency into a single mode telecommunication fiber. The concept has been applied to the development of uncooled lasers, mounted in TO-56 cans, capable of producing 50 to 100 mW of fiber-coupled power. We have also demonstrated the extended cavity lasers at wavelengths of 920 nm and 1064 nm. We present reliability data for the chips used in the extended cavity lasers.