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Montiel I Ponsoda J.J.,Aalto University | Norin L.,Acreo Ab | Ye C.,nLIGHT Corp. | Bosund M.,Beneq Oy | And 3 more authors.
Optics Express | Year: 2012

We report on a new fabrication method of producing ytterbium doped fibers by atomic layer deposition (ALD) in combination with the conventional modified chemical vapor deposition (MCVD) technique. An MCVD soot-preform with a porous layer of SiO2 is coated with layers of Yb2O3 and Al2O3 prior to sintering, using the gas-phase ALD method. An SEM/EDS material analysis study shows that the dopants successfully penetrate the full thickness of 320 μm of the soot layer. An Yb-doped fiber fabricated by this technique shows a background attenuation of 20 dB/km, a uniform longitudinal Yb-doping profile, and good laser characteristics with a slope efficiency of 80%. Furthermore, we present a comparison in terms of photodarkening between the MCVD-ALD fiber and a solution doped fiber, fabricated with the same MCVD recipe. The new MCVD-ALD fiber appears to be more photodarkening resistant. © 2012 Optical Society of America.


Alias M.S.,Telekom Malaysia Research and Development TMR and D | Shaari S.,National University of Malaysia | Leisher P.O.,nLIGHT Corp. | Choquette K.D.,University of Illinois at Urbana - Champaign
Photonics and Nanostructures - Fundamentals and Applications | Year: 2010

Single transverse mode control is achieved for multimode GaAs-based VCSEL by utilizing photonic crystal design and etched trench structure. Theoretical analysis is initially performed for photonic crystal design with various lattice constants and air holes diameter. The fabricated photonic crystal VCSEL with etched trench structure exhibits single mode output power of 0.7 mW, threshold current of 3.5 mA, slope efficiency of 0.10 W/A, and continuous single mode output spectrum throughout a wide operating current range. Comparison of typical oxide VCSEL, trench oxide VCSEL, and photonic crystal oxide VCSEL employing trench structure is presented. By combining photonic crystal and trench structure, single transverse mode operation of photonic crystal VCSEL can be much more strictly controlled. © 2010 Elsevier B.V. All rights reserved.


Di Teodoro F.,Northrop Grumman | Di Teodoro F.,The Aerospace Corporation | Morais J.,Northrop Grumman | McComb T.S.,Northrop Grumman | And 5 more authors.
Optics Letters | Year: 2013

We report on a compactly packaged Yb-doped fiber-based laser architecture featuring an actively pulse controlled, single-longitudinal-mode seeder and multistage amplifier chain terminated by a "folded" rod-type photonic crystal fiber. In this laser source, stimulated Brillouin scattering (SBS) is the power-limiting factor, but is managed by phase modulating the seeder with a pseudo-random noise signal. Pulse energy/peak power of ∼2 mJ/1.5 MW at 10 kHz repetition rate are thus obtained within ∼1.55 ns pulses of peak spectral brightness 20 kW cm-2 sr-1 Hz-1. © 2013 Optical Society of America.


Alias M.S.,Telekom Malaysia Research and Development TMR and D | Shaari S.,National University of Malaysia | Leisher P.O.,nLIGHT Corp. | Choquette K.D.,University of Illinois at Urbana - Champaign
Applied Physics B: Lasers and Optics | Year: 2010

In this letter, we report on single-mode operation of originally multi-mode oxide VCSEL by using etched photonic crystal air holes and unique trench structure. The device fabrication utilized conventional photolithography; with simplified lithography step of self-aligning the photonic crystal and trench structures to the laser aperture for efficient and vigorous device processing. The fabricated photonic crystal VCSEL with trench device exhibits a singlemode output power of 0.7 mW, threshold current of 3.5 mA, slope efficiency of 0.10 W/A, and continuous single-mode output spectra at wide operating current range. The results are compared with conventional multi-mode oxide VCSEL of similar device geometry. In addition, theoretical analysis is presented for developing further understanding of the photonic crystal VCSEL. © Springer-Verlag 2010.


Palese S.,Northrop Grumman | Cheung E.,Northrop Grumman | Goodno G.,Northrop Grumman | Shih C.-C.,Northrop Grumman | And 3 more authors.
Optics Express | Year: 2012

Two high pulse contrast (> 95 dB) polarization maintaining all-fiber amplifier chains were coherently combined to generate 0.42 mJ, 1 ns 25 kHz pulses with 79% efficiency despite 38 radians of intra-pulse phase distortion. A recursive intra-pulse phase compensation method was utilized to correct for the large nonlinear chirp providing a path for improved coherent waveform control of nanosecond pulse trains. © 2012 Optical Society of America.

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