550 mW of blue radiation generated by a frequency doubled mode-locked InGaAs diode laser MOPA system

Abstract

We report on the generation of 550 mW of 460 nm blue radiation by single pass frequency doubling the picosecond pulses of a mode-locked InGaAs diode laser MOPA system in periodically poled KTP.Compact blue laser sources are of interest for many applications such as optical data storage, medical diagnostics, lithography and display technology. Although the operation of blue semiconductor diode lasers has recently been demonstrated [1] the development of reliable high power devices as required for most applications still remains a challenge. Today the blue output of commercially available GaN diode lasers is usually less than 30 mW.An alternative concept for diode laser based blue light sources is the second harmonic generation (SHG) of near infrared diode laser radiation [2]. Appropriate diode laser sources are master oscillator power amplifier (MOPA) systems based on amplifiers with a tapered lateral geometry of the active area. Such devices provide output powers of more than 5 W in a near-diffraction-limited beam [3]. An attractive method for increasing the conversion efficiency is the use mode-locked ultrashort pulses [4]. Because of the high pulse power high SHG efficiencies are achievable in a single pass through periodically poled nonlinear crystals [5]. This concept is much simpler and provides high long-term stability compared e.g. to SHG in external high finesse enhancement cavities [6].In this paper we report on the generation of 550 mW of blue light at 460 nm by single pass frequency doubling of picosecond pulses generated by an InGaAs diode laser MOPA-system in periodically poled KTiOPO3 (KTP). To our knowledge this is the highest average power generated by frequency doubling diode laser radiation without using a resonant enhancement cavity. Fig. 1 Scheme of the experimental setup a828_1.pdf CFG6.pdf 1-55752-813-6/06/$25.00 ©2006 IEEE

Diode laser MOPA system for the generation of 920 nm femtosecond pulses with 65 W peak power

“…By aligning the compressor for shortest pulse duration we found that the pulses emitted by the MOPA system were up-chirped (400 000 fs²). This is in contrast to pulses emitted by actively mode locked laser diodes [5]. The up-chirp is a result of the carrier generation and the dynamic change of the index of refraction in the saturable absorber [6].…”

“…grating compressor adjustable group delay dispersion to beam diagnostics tapered amplifier optical isolator optical isolator master oscillator with saturable absorber output coupler R=30% Fig. 1: Experimental setup of the diode laser MOPA system with passively mode locked oscillator, tapered amplifier and grating compressor.As shown in previous investigations diode laser based MOPA systems are well suited for the generation of mode locked laser radiation [5]. In contrast to broad-area amplifiers or diode stacks tapered amplifiers (TA) provide radiation in a beam of good spatial quality [5].…”

“…As shown in previous investigations diode laser based MOPA systems are well suited for the generation of mode locked laser radiation [5]. In contrast to broad-area amplifiers or diode stacks tapered amplifiers (TA) provide radiation in a beam of good spatial quality [5].…”

“…In contrast to broad-area amplifiers or diode stacks tapered amplifiers (TA) provide radiation in a beam of good spatial quality [5].…”