IXPE, the Imaging X-ray Polarimetry Explorer, is a NASA SMEX mission with an important contribution of ASI that will be launched with a Falcon 9 in 2021 and will reopen the window of X-ray polarimetry after more than 40 years. The payload features three identical telescopes each one hosting one light-weight X-ray mirror fabricated by MSFC and one detector unit with its in-orbit calibration system and the Gas Pixel Detector sensitive to imaging X-ray polarization fabricated by INAF/IAPS, INFN and OHB Italy. The focal length after boom deployment from ATK-Orbital is 4 m, while the spacecraft is being fabricated by Ball Aerospace. The sensitivity will be better than 5.5% in 300 ks for a 1E-11 erg/s/cm2 (half mCrab) in the energy band of 2-8 keV allowing for sensitive polarimetry of extended and point-like X-ray sources. The focal plane instrument is completed, calibrated and it is going to be delivered at MSFC. We will present the status of the mission at about one year from the launch.
We study transparent ceramics made of erbium doped yttria, as a candidate material for quantum storage of photons in the telecom wavelength. Samples with different heat processing conditions are compared. Two different species of Er3+ ions with drastically different dephasing properties are identified. In general, samples processed at lower temperature show narrower inhomogeneous and homogeneous linewidths. We also demonstrate both type I and type II waveguide in the material using a femtosecond laser, with propagation loss of 0.22 dB/mm.
Lenticular lens based autostereoscopic 3D displays are finding many applications in digital signage and consumer electronics devices. A high quality 3D viewing experience requires the lenticular lens be properly aligned with the pixels on the display device so that each eye views the correct image. This work presents a simple and novel method for rapidly assessing the quality of a lenticular lens to be used in autostereoscopic displays. Errors in lenticular alignment across the entire display are easily observed with a simple test pattern where adjacent views are programmed to display different colors.
This paper describes the observation of a fiber fuse observed in the core of a high-power high-NA, all-glass, double-clad fiber. Fiber fuse is a phenomenon that results in a specific type of
catastrophic destruction of an optical fiber-core from the point of initiation toward the light
source. It is so named because its appearance is very similar to a burning fuse. In this paper, we
examine the origin or the initiation source for the fiber fuse observed in the double-clad fiber.
Furthermore, we propose a two-step thermal mechanism for the fiber-fuse generation in optical
High power fiber lasers have been recently demonstrated at the kilowatt level. The
spectral linewidths of these lasers oscillators can exceed 20 nm. Whereas, such broad
spectra are fine for many applications, such as materials processing where raw power is
the primary requirement, other applications, including coherent beam combination,
harmonic generation, or gravitational wave detection, require high powers beams with
much narrower linewidths. Amplification of narrow linewidth signals in optical fibers is
limited by stimulated Brillouin scattering (SBS). We discuss novel fiber designs that limit
SBS allowing the amplification of narrow linewidth signals to kilowatt power levels.
This paper reviews different fiber design approaches for high power lasers. First, we discuss the conventional step index
profile design and methods for achieving single mode operation in high power lasers such as bending, helical core fibers
and Yb dopant profile designs. Then we present new design approaches for reducing the SBS through profile and glass
composition designs. Finally, we describe fiber designs to achieve single polarization and at the same time to mitigate
the SRS effect.
This paper outlines recent work at Corning Incorporated on fiber composition design and fabrication of a SBS-managed, large-mode-area (LMA), Yb-doped double-clad fiber for high-power, narrow-linewidth fiber laser applications. Through a detailed theoretical analysis for the SBS threshold in optical fibers, an Aluminum/Germanium (Al/Ge) counter-graded fiber-core composition profile has been proposed and demonstrated for reducing the SBS effect, via the reduced-overlap between optical and acoustic modes in the fiber design. Such Al/Ge counter-graded-composition-profile design overcomes the limitation in a multilayer fiber-core approach, in terms of the low-loss fiber fabrication. The new compositionally SBS-managed, LMA Yb-doped double-clad laser fiber fabricated through the new design, has shown more than ~7 dB improvement in SBS threshold over the conventional LMA fiber design. The new fiber offers exceptionally low passive-loss characteristics, and has been demonstrated with uncompromised high laser efficiency for high-power, narrow-linewidth fiber laser applications.
Single transverse mode fiber lasers have recently achieved output powers at the kilowatt level. These breakthroughs can be attributed to the maturation of high power diode pump technology at 980 nm and the use of large mode area (LMA) fibers. In the continous wave (cw) operation regime, LMA fibers, through their reduction of device length and increase of the effective area, have been effective in the reduction of deleterious nonlinear optical effects such as stimulated Raman scattering (SRS). The use of LMA fiber has been less effective in the suppression of stimulated Brillouin scattering (SBS), for which the threshold can be several orders of magnitude lower than for SRS. In this work we use refractive index profiles and index modifying dopant distributions for the mitigation of SBS. Our theoretical and modeling efforts led to an experimentally demonstrated increase in SBS threshold of 2.5 dB for single mode fiber and 6 dB for LMA amplifier fiber. We discuss the use of this SBS-suppressive fiber in the demonstration of a high-power,
narrow linewidth fiber amplifier.
We have demonstrated high power, linearly polarized output from an
all-fiber laser using an integrated polarizing fiber. In this
paper, we will detail the design, fabrication and operation of the
single polarization fiber as well as the fiber laser experiments.
We present a detailed description of a passive harmonically mode-locked laser. Experimental results are consistent with the suggestion of a passive self-stabilization effect driven by transverse acoustic wave excitation due to electrostriction. We also demonstrate some applications of the laser.