In this paper, we demonstrate a broadband anti-reflective (AR) coating over the mid-IR fluoride fiber endface (tip) for high power laser applications. The AR coating consists of multiple-pair Lithium fluoride (LiF) and Al2O3, and was deposited by electron beam physical vapor deposition with an iron assistant source at low temperature (<60°C). In addition, a super thin encapsulation layer (~20nm) of Al2O3 was applied over the AR coating by both traditional PVD and atomic layer deposition technology. The measurements show the coating has a reflectivity of < 1-1.5% in the range of 1.5-5.5μm. The laser induced damage threshold (LIDT) test using high power quantum cascade laser (QCL) shows the damage threshold is greater than 10 MW/cm2 with no sign of any damage on the coating. The durability and environmental tests of the AR coating with PVD coated encapsulation layer show good humidity resistance in open air and 95 RH% at 50ºC for 48 hours, no degradation of film quality and optical performance are observed. Further comparison study of ALD encapsulation layer vs pure PVD layers in more aggressive water vapor testing indicates ALD encapsulation layer has better moisture resistance.
KEYWORDS: Crystals, Control systems, Data modeling, Polarization, Neural networks, Machine learning, Electron beams, Visual process modeling, Systems modeling, Dysprosium
The Pockels Cells play important role in generating helicity-flipping polarized laser beam to be used in high energy electron beam accelerator facility. Due to exceptional requirements for ultra-stable electron beam in modern nuclear physics experiment, the operation of Pockels Cells which are key components to generate stable electron beam becomes critical. However, since the operation of Pockels Cell, which usually work in pair, involves beam alignments up to 12 degrees of freedom, it requires extremely complicated controls to maintain the stable output beam through whole operation time of accelerator. In this paper, we combined the machine learning method with the Pockels Cells control system, automatically collected data of Pockels cells optical properties such as polarization extinction ratio (PER), beam position, optical intensity asymmetry, etc., at different orientation angles and physical potions, and built an artificial neural network which can determine the optimal position of Pockels Cells. The trained artificial neural network can predict the PER, intensity asymmetry, beam position difference with a mean agreement around 95%, which makes it possible to find the optimal yaw/pitch/roll angles and physical positions of the Pockels cells in a short time. This technology can also be translated to alignments of devices in other laser systems such as high energy ultrafast oscillators and amplifiers.
A 1550 nm polarization-insensitive superluminescent diode (SLED) has been demonstrated with >100 mW continuous wave (CW) output power. More than 40 nm FWHM bandwidth of a Gaussian-shape spectrum, and less than 0.7 dB peak-to-peak ripple were also achieved with a polarization dependence of the output power spectrum that is less than 1 dB over 1530-1610 nm.
A 1310nm superluminescent diode (SLED) has been demonstrated with > 80mW continuous wave (CW) output power at 25 0C with a spectral bandwidth of > 60nm and peak-to-peak modulation of < 0.6dB. Low power ( ~ 4 mW), ultrawide bandwidth ( ~ 95nm) SLED can also be realized using the same structure but shorter cavity length.
We report on half-Watt level single spatial mode superluminescent laser diode at 1335 nm. Output optical power in excess of 500 mW from a single facet of angle-striped waveguide was realized at 10°C of heatsink temperature with peak electro-optical efficiency of 28%. To our knowledge this is the highest optical power and electro-optic conversion efficiency in a SLED device reported so far in the literature. Further optimization could lead to revolutionary result: 1) the creation of a high power optical device (SLED) with electro-optical efficiencies approaching and/or exceeding that of Fabry-Perot lasers (counting both facet outputs) with absolute optical power levels compared to that of Fabry-Perot lasers, 2) Electro-optical efficiencies approaching internal quantum efficiencies which could well exceed the 70-80% range observed in present commercial semiconductor laser and light-emitting structures.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.