Diode-pumped Erbium Research Articles

High Power Diode-Pumped Erbium Laser Emitting at Near 1.5 μm

Solid-state lasers emitting in the 1.5–1.6 μm spectral range are very promising for eye-safe laser range finding, ophthalmology, fiber-optic communication systems, and optical location. The aim of this work is the investigation of spectrosposcopic and laser properties of gain medium based on borate crystal for abovementioned lasers.Spectroscopic and laser properties of Er,Yb:YAl3(BO3)4 crystals with different concentrations of dopants were investigated. Polarized absorption and emission cross-section spectra were determined. The ytterbium- erbium energy transfer efficiency was estimated. The maximal energy transfer efficiency up to 97 % was obtained for Er(4 at.%),Yb(11 at.%):YAl3(BO3)4 crystal.The laser operation of heavily doped crystals with erbium concentration up to 4 аt.% (2.2^1020 cm^3) was realized. By using of Er(2 at.%),Yb(11 at.%):YAl3(BO3)4 crystal a maximal continuous- wave (CW) output power of 1.6 W was obtained at 1522 nm with slope efficiency of 32 %. By using of Er(4 at.%),Yb(11 at.%):YAl3(BO3)4 crystal a maximal peak output power up to 2.2 W with slope efficiency of 40 % was realized in quasi-continuous-wave regime of operation. The spatial profile of the output beam was close to TEM00 mode with M2 < 1.2 during all laser experiments.Based on the obtained results, it can be concluded that Er,Yb:YAl3(BO3)4 crystals are promising active media for lasers emitting in the spectral range of 1.5-1.6 pm for the usage in laser rangefinder and laser- induced breakdown spectroscopy systems, and LIDARs.

Passively Q-Switched 2.8-$\mu{\rm m}$ Nanosecond Fiber Laser

A diode-pumped erbium ion-doped single-mode ZBLAN fiber laser passively Q-switched by a Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> :ZnSe crystal is reported. Mid-infrared (MIR) pulses at 2.8 μm with a pulse energy of 2.0 μJ and pulse duration of 370 ns, corresponding to a peak power of 5.34 W, are achieved at a repetition rate of 161 kHz. Our experiment demonstrates that Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> : ZnSe crystal is a promising Q-switching element for high power pulsed MIR fiber lasers.

Fractional Photothermolysis for Photoaging of Hands

Laser treatment for photoaging of the hands should ideally address pigmentary alteration as well as associated skin roughness and wrinkling. Fractional resurfacing has been previously shown to effectively treat facial rhytids and dyschromia. We examined the effect of fractional resurfacing for photoaging of the hands. Ten patients (skin phototypes II to IV) with hand photodamage were randomized to receive five treatments with a 1,550-nm diode-pumped erbium fiber laser (Fraxel SR, Reliant Technologies) laser on either the right or left hand. Treatments were performed at settings of 8 to 9 mJ/microscopic treatment zone and density of 2,500 microscopic treatment zones/cm2. Subjective assessments by the patients and investigator were performed for skin roughness, wrinkling, and pigmentation using a 5-point scale. Skin biopsies were taken at baseline and at 1 and 3 months. Patient subjective assessment and physician clinical assessment at 1 and 3 months revealed a mean 51% to 75% improvement in skin pigmentation and 25% to 50% improvement in skin roughness and wrinkling. Biopsies of the skin showed increased density of dermal collagen. Patients experienced transient erythema and edema and none had scarring or other adverse effects. This was a small study. Fractional resurfacing appears to be an effective and safe treatment modality for correcting both the pigmentary and the textural aspects of photoaging of the hand.

Passive Q switches for a diode-pumped erbium glass laser

A diode-pumped, passively Q-switched 1.54-μm erbium glass laser is studied. Zinc selenide (ZnSe) crystals doped with Co2+ and Cr2+ ions and magnesium—aluminium spinel (MgAl2O4) crystals doped with Co2+ ions were used as saturable absorbers in Q switches. It is shown that, depending on the type of a saturable absorber, the pump power, and the resonator design, the laser pulse energy can vary from 0.2 to 13 μJ, the pulse duration from 16 to 980 ns, and the pulse repetition rate from 0.1 to 30 kHz.

Longitudinally diode-pumped ytterbium-erbium glass minilaser

The prototype of a passively Q-switched, longitudinally diode-pumped erbium glass laser is fabricated. A slope efficiency of 38% is achieved in the free-running lasing regime. It is shown that a pump energy of only 42 mJ is required to generate a 9-ns, 1.8-mJ output pulse with efficiency 4.2%.

Modelling of high-power diode-pumped erbium 3 μ m fibre lasers

Modelling of high-power diode-pumped erbium 3 μ m fibre lasers

Modelling of high-power diode-pumped erbium 3 μm fibre lasers

We present theoretical calculations that relate to the cw operation of a high-power Er3+, Pr3+:ZBLAN double-clad fibre laser. Using the measured energy-transfer, energy-transfer-upconversion and cross-relaxation parameters relevant to Er3+-doped and Er3+, Pr3+-codoped ZBLAN, we compare the theoretical calculations from the model with recent experimental measurements. The model is then used to analyse the important pump and interionic processes occurring in Er3+, Pr3+:ZBLAN fibre lasers. The theoretical results indicate that energy transfer from Er3+ to Pr3+ leads to a fast depletion of the lower laser level and, due to the cw threshold condition, to low population densities in both laser levels. Thus, ground-state bleaching, pump excited-state absorption and energy-transfer upconversion amongst the Er3+ ions are avoided.

Frequency stability measurements of 1.5 μm erbium lasers locked to acetylene absorption lines

We report on the absolute frequency stabilization of Yb-Er:glass lasers against different acetylene absorption lines in the 1.5 /spl mu/m spectral region. An external frequency modulation technique was adopted to independently stabilize two diode-pumped erbium microlasers against the P(15) rovibrational line at 1534.099 nm. A long-term frequency stability below 10/sup -9/ (200 kHz) was measured on both the closed-loop error signal and on the beat note frequency. From the beat signal analysis, a 1 ms laser linewidth of 50 kHz was observed. The Allan standard deviation of the beat frequency was below 10/sup -10/ for integration times between 10 ms and 1 s and as low as 4/spl times/10/sup -11/ around 0.1 s.

The route toward a diode-pumped 1-W erbium 3-μm fiber laser

A rate-equation analysis of the erbium 3-/spl mu/m ZBLAN fiber laser is performed. The computer calculation includes the longitudinal spatial resolution of the host material. It considers ground-state bleaching, excited-state absorption (ESA), interionic processes, lifetime quenching by co-doping, and stimulated emission at 2.7 /spl mu/m and 850 mn. State-of-the-art technology including double-clad diode pumping is assumed in the calculation. Pump ESA is identified as the major problem of this laser. With high Er/sup 3+/ concentration, suitable Pr/sup 3+/ co-doping, and low pump density, ESA is avoided and a diode-pumped erbium 3-/spl mu/m ZBLAN laser is predicted which is capable of emitting a transversely single-mode output power of 1.0 W when pumped with 7-W incident power at 800 nm. The corresponding output intensity which is relevant for surgical applications will be in the range of 1.8 MW/cm/sup 2/. Compared to Ti:sapphire-pumped cascade-lasing regimes, the proposed approach represents a strong decrease of the requirements on mirror coatings, cavity alignment, and especially pump intensity. Of the possible drawbacks investigated in the simulation, only insufficient lifetime quenching is found to have a significant influence on laser performance.

Single-frequency diode-pumped erbium lasers at 1.55and 1.64 µm

Single-frequency operation of a diode-pumped Er:YAG laser at 1.64 µm has been achieved for the first time with a new type of semi-monolithic laser in a cleaved coupled cavity (C3). This C3 configuration can also be used for other laser materials, for single-frequency operation with Er:Yb:glass at 1.55 µm and in a sandwich combination from Er:Yb:glass and Er:YAG, for example.

Self-starting sliding-frequency fibre soliton laser

The authors demonstrate self-starting soliton generation by inserting a travelling wave acousto-optic modulator and a bandpass filter in a diode-pumped erbium doped fibre ring laser. The continuous frequency sliding of the circulating light inhibits CW oscillation, and favours the emission of solitons that are stably trapped by the filter.

Broadband tunable single frequency diode-pumped erbium doped fibre laser

A single frequency erbium fibre laser with continuous wavelength tuning over the range 1525–1568 nm has been demonstrated using a unidirectional loop mirror (ULM) configuration. The fibre laser is diode pumped at 1480 nm with a threshold of 9mW, slope efficiency of 12% and has a linewidth of less than 295 kHz.

Mode-locked erbium fibre laser with wavelength selection by means of fibre Bragg grating reflector

Mode-locked operation of a diode-pumped erbium doped fibre laser is described in which an optically written fibre Bragg reflection grating is used to define the operating wavelength. Pulses of 35 ps duration have been generated at a repetition rate of 5 GHz with mean (peak) output powers of 5mW(29mW).

Field demonstration of coherent transmission system with diode-pumped erbium doped fibre amplifiers

We report a field demonstration of 622 Mbit/s DPSK and FSK coherent transmission over 200 km of installed single mode fibre. Diode-pumped erbium doped fibre amplifiers were used as both power amplifiers and repeaters. System loss budgets of more than 68 dB were achieved with an intermediate amplifier repeater gain of 16.5 dB. Both systems incorporated fully automated endless polarisation control.