Average Output Power In Excess Research Articles

High power, higher order ultrafast hollow Gaussian beams

We report on linear and nonlinear generation of ultrafast hollow Gaussian beams (HGBs). Using only two spiral phase plates (SPPs) having phase variation corresponding to vortex orders, l = 1 and 2, and an experimental scheme, we have generated high power, ultrafast HGBs of orders up to 3 at 1064 nm. Based on single-pass, frequency doubling of the HGBs in a 5 mm long, MgO doped, periodically poled LiNbO3 (MgO:PPLN) crystal, we have produced HGBs of average output power in excess of 250 mW at 532 nm and order as high as 6. Experimentally, we verified that the frequency doubled HGBs have orders twice those of the pump HGBs. Like the Gaussian beams, the HGBs of all orders have an optimum focusing condition for the highest conversion efficiency. On the contrary to previous reports, we observed that the propagation of the vortex beam of order, l, through a SPP corresponding to the vortex order of, –l, results in HGBs of the same order, |l|.

Watt-level passively mode-locked Er(3+)-doped ZBLAN fiber laser at 2.8 μm.

We experimentally demonstrated a stable, high-average-power, continuous-wave (CW) passively mode-locked Er(3+)-doped ZBLAN fiber laser at 2.8 μm based on a semiconductor saturable absorber mirror. A stable mode-locked laser with a signal-to-noise ratio of 52 dB and a slope efficiency of 14% was obtained. The highest average output power in excess of 1 W was generated at the incident pump power of 8.2 W, with a pulse repetition rate of 22.56 MHz and pulse duration of 25 ps. To the best of our knowledge, this is the highest average output power of a CW mode-locked ZBLAN fiber laser in the mid-infrared wavelength regime up to now.

Highly efficient tunable mid-infrared optical parametric oscillator pumped by a wavelength locked, Q-switched Er:YAG laser.

A highly efficient and stable mid-infrared optical parametric oscillator is demonstrated, pumped by an electro-optic Q-switched Er:YAG laser with operating wavelength locked at 1645 nm by a volume Bragg grating. The oscillator, based on MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal, yields a maximum overall average output power in excess of 1 W, corresponding to a conversion efficiency of 35.5% and a slope efficiency of 43.6%. The signal and idler wavelengths of the OPO are around ~2.7 μm and ~4.3 μm, respectively, corresponding to the two peak absorption bands of CO(2). Lasing characteristics of the oscillator, including the time evolution of the pump, signal and idler pulses at different pump power levels, are also investigated. Temperature tuning of the MgO:PPLN crystal gives signal and idler ranges of 2.67 to 2.72 μm and 4.17 to 4.31 μm, respectively.

Fourier domain mode-locked swept source at 1050 nm based on a tapered amplifier

While swept source optical coherence tomography (OCT) in the 1050 nm range is promising for retinal imaging, there are certain challenges. Conventional semiconductor gain media have limited output power, and the performance of high-speed Fourier domain mode-locked (FDML) lasers suffers from chromatic dispersion in standard optical fiber. We developed a novel light source with a tapered amplifier as gain medium, and investigated the FDML performance comparing two fiber delay lines with different dispersion properties. We introduced an additional gain element into the resonator, and thereby achieved stable FDML operation, exploiting the full bandwidth of the tapered amplifier despite high dispersion. The light source operates at a repetition rate of 116 kHz with an effective average output power in excess of 30 mW. With a total sweep range of 70 nm, we achieved an axial resolution of 15 microm in air (approximately 11 microm in tissue) in OCT measurements. As our work shows, tapered amplifiers are suitable gain media for swept sources at 1050 nm with increased output power, while high gain counteracts dispersion effects in an FDML laser.

56-W Frequency-Doubled Source at 530 nm Pumped by a Single-Mode, Single-Polarization, Picosecond, Yb$^{3+}$-Doped Fiber MOPA

We report a frequency-doubled green source at 530 nm pumped based on an all-fiber, picosecond, single-polarization Yb 3+-doped fiber master oscillator power amplifier (MOPA) delivering 20-ps pulses at user selectable repetition rates of up to 910 MHz and an average output power in excess of 100 W at 1.06 ?m. The output of the MOPA was frequency-doubled using a lithium triborate crystal. Up to 56 W of green light was generated at a corresponding repetition rate of 227 MHz at an overall conversion efficiency of 56%. The diode-to-green optical power conversion efficiency was 37%.

Subpicosecond thin-disk laser oscillator with pulse energies of up to 259 microjoules by use of an active multipass geometry

The pulse shaping dynamics of a diode-pumped laser oscillator with active multipass cell was studied experimentally and numerically. We demonstrate the generation of high energy subpicosecond pulses with a pulse energy of up to 25.9 microJ at a pulse duration of 928 fs directly from a thin-disk laser oscillator. These results are achieved by employing a selfimaging active multipass geometry operated in ambient atmosphere. Stable single pulse operation has been obtained with an average output power in excess of 76 W and at a repetition rate of 2.93 MHz. Self starting passive mode locking was accomplished using a semiconductor saturable absorber mirror. The experimental results are compared with numerical simulations, showing good agreement including the appearance of Kelly sidebands. Furthermore, a modified soliton-area theorem for approximating the pulse duration is presented.

Passively mode-locked Yb:YAG thin-disk laser with pulse energies exceeding 13 μJ by use of an active multipass geometry

We demonstrate the generation of high-energy picosecond pulses directly from a thin-disk laser oscillator by employing a self-imaging active multipass geometry. Stable single-pulse operation has been obtained with an average output power in excess of 50 W, excluding a cw background of 8%, at a repetition rate of 3.8 MHz. Self-starting passive mode locking was accomplished using a semiconductor saturable absorber mirror. The maximum pulse energy was 13.4 microJ at a pulse duration of 1.36 ps with a time-bandwidth product of 0.34. Single-pass external frequency doubling with a conversion efficiency of 60% yielded >28 W of average power at 515 nm.

Simple, compact, high-repetition rate XeCl laser

Operation of a compact, corona-preionized, XeCl excimer laser producing average output power in excess of 1 W at pulse repetition frequencies of up to 750 Hz is reported. This device is simple in construction and utilizes all commercially available components.

New phosphate glass for lasers with a high repetition frequency of output pulses

Some lasing characteristics were determined for a new Na–Al phosphate glass of the LGS-T type characterized by a higher thermal conductivity and thermal stability than the known phosphate glasses and by a fairly high thermal expansion coefficient, which made it possible to synthesize athermal glasses. No concentration quenching of the neodymium luminescence was observed when this glass contained up to 6 wt.% Nd2O3. Active elements in the form of rods 8 mm in diameter and 100 mm long were capable of an average output power in excess of 20 W at a repetition frequency of 15 Hz. The investigated glass had good technological characteristics and could be manufactured on a large scale.