RESUMEN
Mode-locked mid-infrared (MIR) fiber laser research has been dominated by the generation of pulses in the picosecond regime using saturable absorbers (SAs) and more recently frequency shifted feedback (FSF). Despite the significant emphasis placed on the development of materials to serve as the SAs for the MIR, published pulse durations have been substantially longer than what has been reported in the near-infrared (NIR). In this report we present experimental data supporting the view that the majority of demonstrations involving SAs and FSF have been limited by the presence of molecular gas absorption in the free-space sections of their cavities. We show that the pulse duration is directly linked to the width of an absorption-free region of the gaseous absorption profile and that the resulting optical spectrum is nearly always bounded by strong absorption features.
RESUMEN
We demonstrate operation of a mid-infrared dysprosium-doped fiber laser with emission at 3388 nm, representing the longest wavelength yet achieved from this class of laser, to the best of our knowledge. Oscillation far removed from the Dy3+ gain peak around 3 µm is achieved through the design of a high feedback optical cavity employing a directly inscribed fiber Bragg grating as the output coupler. Laser performance is characterized by a slope efficiency with respect to injected pump power of 38% and maximum output power of 134 mW, an improvement of at least three orders of magnitude over prior attempts at long wavelength Dy3+ fiber laser operation. This wavelength coincides with a maximum in the absorption coefficient of PMMA, which we exploit for preliminary demonstration of the utility of this source in polymer processing.
RESUMEN
In this Letter, we demonstrate electronically tunable picosecond (ps) pulse emission from the 5I6-5I7 transition of the Ho3+ ion by using an acousto-optic tunable filter. The holmium- and praseodymium-codoped ZBLAN fiber laser produced sub-50 ps pulses over a 100 nm tuning range, critically reaching a longest wavelength of 2.94 µm, which overlaps with the peak absorption of liquid water. Measured pulse energies of 8.1 nJ well exceed those expected from picosecond solitonic operation, suggesting possible application in ablative medicine. Furthermore, we present harmonically mode-locked operation of the oscillator, which indicates the possibility of expanding the capabilities of mid-infrared frequency shifted-feedback lasers through the ability to achieve higher pulse repetition rates.
RESUMEN
We report the demonstration of a Dy3+-doped ZBLAN fiber laser directly diode-pumped at 800 nm utilizing a codoping scheme with Tm3+ serving as the donor ion. In this initial demonstration, a modest output power of 12 mW is generated with a slope efficiency of 0.3% at an emission wavelength of 3.23 µm. Energy transfer dynamics are investigated through excited state lifetime analysis and comparison to resonant pumping of the Dy3+ upper state. The likely presence of an energy transfer upconversion process is identified, which has an undesirable effect on 3 µm class lasers but may be of significant benefit for future 4 µm systems.
RESUMEN
We demonstrate ultrashort pulse generation from a fluoride fiber laser co-doped with holmium and praseodymium. To date, the majority of work focused on short pulse generation from this class of fiber laser has employed loss modulators in the cavity, both real and artificial. In this Letter, we alternatively employ a frequency shifting element: an acousto-optic modulator (AOM) in the cavity. This results in mode-locked output of sub-5 ps pulses with 10 nJ of energy at a center wavelength of 2.86 µm and a pulse repetition frequency of 30.1 MHz, equating to a peak power of 1.9 kW. Additional experimental investigation of the relationship between frequency shift and cavity round trip offer insight into the complex underlying dynamics. As a complementary mode-locking technique to conventional loss modulation, this method of pulse-formation may greatly expand the design flexibility of pulsed mid-infrared fiber lasers.
RESUMEN
Optical emission from rare-earth-doped fluoride fibers has thus far been limited to less than 4 µm. We extend emission beyond this limit by employing an indium fluoride (InF3) glass fiber as the host, which exhibits an increased infrared transparency over commonly used zirconium fluoride (ZBLAN). Near-infrared pumping of a dysprosium-doped InF3 fiber results in broad emission centered around 4.3 µm, representing the longest emission yet achieved from a fluoride fiber. The first laser emission in an InF3 fiber is also demonstrated from the 3 µm dysprosium transition. Finally, a frequency domain excited state lifetime measurement comparison between fluoride hosts suggests that multiphonon effects are significantly reduced in indium fluoride fiber, paving the way to more efficient, longer wavelength lasers compared to ZBLAN fibers.
RESUMEN
We demonstrate a mid-infrared dysprosium-doped fluoride fiber laser with a continuously tunable output range of 573 nm, pumped by a 1.7 µm Raman fiber laser. To the best of our knowledge, this represents the largest tuning range achieved to date from any rare-earth-doped fiber laser and, critically, spans the 2.8-3.4 µm spectral region, which contains absorption resonances of many important functional groups and is uncovered by other rare-earth ions. Output powers up to 170 mW are achieved, with 21% slope efficiency. We also discuss the relative merits of the 1.7 µm pump scheme, including possible pump excited-state absorption.
RESUMEN
We report the demonstration of a tunable dysprosium laser. The experiment employed in-band pumping of a Dy3+-doped fluoride fiber and a simple resonator design involving a ruled diffraction grating. The laser produced tuning between 2.95 and 3.35 µm, limited by the availability of optics.
RESUMEN
A new, highly efficient and power scalable pump scheme for 3 µm class fiber lasers is presented. Using the free-running 2.8 µm emission from an Er3+-doped fluoride fiber laser to directly excite the upper laser level of the H13/26âH15/26 transition of the Dy3+ ion, output at 3.04 µm was produced with a record slope efficiency of 51%. Using comparatively long lengths of Dy3+-doped fluoride fiber, a maximum emission wavelength of 3.26 µm was measured.
