This paper presents our latest experimental results of welding and cutting of steel and aluminum using a High Power, High Brightness Direct Diode Laser (DDL) upgraded with a Laser-Integrated Dynamic Beam Shaper (DBS). TeraDiode’s DDLDBS laser system transforms the beam distribution from Gaussian-like to Doughnut shape, and a beam parameter product from 4 to 25mm·mrad and doing so in a continuous, real-time manner with very low latency below 10ms. These capabilities unlock a wide range of processing parameters and an overall improved quality for metal cutting and welding while using simplified processing heads. This capability can be applied to DDL from 500W to 8000W power range.
TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, <0.08 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. Our TeraBlade industrial platform achieves world-record brightness levels for direct diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.
TeraDiode has produced kW-class ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode
laser with a power level of 2,040 W from a 50 μm core diameter, 0.15 numerical aperture (NA) output fiber at a single
center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using
COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.75 mm-mrad and is
the lowest BPP kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing
applications, including sheet metal cutting and welding. This 2-kW fiber-coupled direct diode laser has comparable
brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode
Fiber lasers are advancing rapidly due to their ability to generate stable, efficient, and diffraction-limited beams with
significant peak and average powers. This is of particular interest as fibers provide an ideal pump source for driving
parametric processes. Most nonlinear optical crystals which provide phase-matching to the mid-IR at commercially
available fiber pump wavelengths suffer from high absorption above 4μm, resulting in low conversion efficiencies in the
4-5μm spectral region. The nonlinear optical crystals which combine low absorption in this same spectral region with
high nonlinear gain require pumping at longer wavelengths (typically >1.9μm). In this paper, we report a novel mid-IR
OPO pumped by a pulsed thulium-doped fiber laser operating at
2-microns. The eyesafe thulium-fiber pump laser
generates >3W of average power at >30kHz repetition rate with
15-30ns pulses in a near diffraction-limited beam. The
ZnGeP2 (ZGP) OPO produces tunable mid-IR output power in the
3.4-3.99μm (signal) and the 4.0-4.7μm (idler) spectral
regions in both singly resonant (SRO) and doubly resonant (DRO) formats. The highest mid-IR output power achieved
from this system was 800mW with 20% conversion efficiency at 40kHz. In a separate experiment, the 3W of 2-micron
light was further amplified to the 20W level. This amplified output was also used to pump a ZGP OPO, resulting in 2W
of output power in the mid-IR. To our knowledge, these are the first demonstrations of a fiber-pumped ZGP OPO.
Realization of microelectromechanically wavelength tunable Fabry-Perot filters using high index-contrast distributed Bragg reflectors (DBRs) comprising GaAlAs/AlOx and Si/SiO2 material system are reported. Due to the broadband nature of these high index-contrast DBRs, the 3dB transmission bandwidth of the cavity resonance is narrow and stable over the tuning range. While the three different sets of GaAlAs/AlOx based filters with different number of DBRs exhibited linewidths of 0.5nm, 2.0nm and 0.47nm with tuning ranges of 59nm, 83nm, and 60nm respectively, the silicon-based filter exhibited a linewidth of 0.3nm and a tuning range of 12nm. Transmission spectra from these devices displayed varying magnitudes of higher order spatial modes were attributed to lensing effect caused by partially oxidized AlGaAs layers within the mirror layers. One of the GaAlAs filters showed a frequency response of 500 KHz at 3dB cutoff point indicating a switching time of 2 microseconds.
In this paper we report novel high contrast, high reflectivity n+-AlGaAs/GaAsAl/Ag asymmetric Fabry-Perot (ASFP) optical modulators and self-electro-optic devices (SEED) using the Franz-Keldysh (FK) electroabsorption in bulk GaAlAs layer. These modulators exhibit `normally off' and `normally on' optical modulation at and below the band edge with contrast ratios in the range of 25:1 to 200:1 and reflectivities of about 30% to 50%. We show that our experimental data is consistent with a model of electroabsorption that includes unbound excitons. The FK-SEED, exhibiting contrast rations of approximately 90:1 and reflectivities of 27% at 11 V, operates based on the combined effects of negative electroabsorption and the `normally off' properties of the device. In addition to these devices operating in the 10 nm vicinity of the GaAs band gap (872 nm), we also report a high contrast modulator with Ga0.975Al0.025As FK layer operating at the standard 850 nm wavelength. These devices demonstrate the feasibility of using the bulk Franz-Keldysh effect as an alternative to quantum confined stark effects (QCSE) for efficient optical switching and modulation for many applications.
Foster-Miller is developing a new family of SLM devices, based on the Franz-Keldysh (FK) effect in bulk III-V semiconductors, for several applications in optical signal processing and switching. Spatial light modulators constructed using the FK effect offer contrast ratios and switching energies rivalling state-of-the-art devices. However, our devices require typically only 2 or 3 bulk epilayers (available commercially), significantly reducing the materials and fabrication cost. Using the FK effect in an asymmetric Fabry-Perot geometry, we demonstrate high contrast (120:1 best, 50:1 typical) with drive voltages roughly 10 - 20 V and 2 - 3 nm optical bandwidth. We demonstrate high-contrast reflection mode optical modulation at a number of wavelengths in the 800 - 950 nm band.