Ytterbium-erbium Laser Research Articles

Pulse power supply of diode-pumped solid-state lasers

Recently, solid-state pumped semiconductor lasers have become increasingly widespread. Lasers of this type have several advantages over solid-state lasers with lamp pumping. First of all, this is high efficiency, long service life, small dimensions and weight. The use of semiconductor laser diodes for pumping solid-state active media imposes a number of rather stringent requirements on the power sources of laser diodes. The power source should provide rectangular current pulses with a flat top, a steep leading edge of the pulses and the absence of reverse current surges at the trailing edge.A pulsed power source for a diode pump system of a ytterbium-erbium laser was developed, manufactured and studied. In this source, the control unit provides functions for protecting the load in emergency conditions, controlling the charge of the storage capacitors to the required voltage and generating current pulses to power the laser diode line. The current is regulated by a field effect transistor operating in a linear mode. The load is included in the source circuit of the field-effect transistor, and the reference signal is generated by the DAC of the microcontroller. Such an approach made it possible to create a relatively simple, reliable and small-sized laser power source with a wide range of adjustment of the duration and amplitude of current pulses. This makes it possible to select the optimal operating mode depending on the characteristics of the active medium of the laser. Particular attention is paid to solving the problems of protecting expensive rulers of laser diodes from failure. The developed source can be used to pump other solid-state lasers with shorter lifetimes of the upper laser level than erbium.

Laser on erbie glass with diode pumping

The results of studies aimed at the development and creation of an erbium-diode-laser laser with diode pumping and providing an output energy of several millijoules in pulses of 20-30 ns duration at a repetition rate of 0.5-1.0 hertz are presented.The interest around this laser is due to the fact that its radiation falls into the spectral region, which is relatively safe for vision. In this spectral region there is a transparency window in the earth's atmosphere. Thus, half-micron radiance can be used efficiently for location aims and rangefinder. This is facilitated by the presence of highly sensitive uncooled photo detectors. In addition, the spectral region of 1.5-1.6 μm matches with the region of maximum transparency of quartz optical fibers used in fiber-optic communication lines.The experimental sample of ytterbium-erbium laser emitting at a wave length of 1, 54 μm was designed and manufactured. Pumping of active element was done according to the transverse scheme by two laser diode rulers with a power of 100 W each, which has been put in line. The selected pump scheme provides a high excitation power and eliminates the occurrence of a temperature gradient in the active element. To increase the pumping efficiency, a cylindrical active laser element was placed in a sapphire cylinder, the outer surface of which had a reflective coating. During free generation regime, we implemented the optimization of laser characteristics, depending on the Q-factor of resonator and excitation conditions. To obtain a giant impulse, a passive Q-switch based on aluminum-magnesium spinel with cobalt was used in the work. In the Q-switched mode, single pulses with the energy of 6 mJ were obtained with a duration of less than 30 ns at a pulse repetition rate of one hertz.

Optimal fill factor for laser diode arrays applied to transversally pumped erbium laser

A relationship between the laser diode array (LDA) near field fill factor, the power of the amplified spontaneous emission fluxes developed within the LDA active layer and the operation efficiency of the ytterbium–erbium glass laser transversally pumped by the laser diode arrays has been studied taking into account the electric and optical processes in the LDA heterostructure layers. It has been found that there is a critical value of the fill factor (0.65–0.85) below of which an abrupt rise of the ytterbium–erbium laser threshold as well as the decrease of the laser operation efficiency is observed. It has been shown that the increase in the InGaAs/AlGaAs LDA fill factor leads to the increase in the LDA threshold current related with the increase of the ASE flux power. For a suppression of the ASE flux power value it has been proposed to etch the LDA heterostructure emitter layer between the stripe contacts.

Spatial and polarization properties of the output beam of an ytterbium-erbium laser with transverse diode pumping

The propagation parameter M2 of the beam of an ytterbium-erbium glass laser with transverse diode pumping has been experimentally investigated for various cavity configurations. The polarization characteristics of the laser radiation are presented for cases in which the active medium is excited by two and four linear laser-diode arrays.

Characterization of Yb–Er:glass lasers at 1.5 μm wavelength in terms of amplitude and frequency stability

The 1.5 μm ytterbium–erbium laser was extensively investigated in terms of its intensity and frequency noise characteristics. The energy transfer process between Yb and Er ions in the codoped active material was shown to reduce substantially the intensity noise induced by pump power fluctuations. To further suppress the intensity noise, a suitable control loop acting on the injection current of the pump laser diode was employed, providing for a 30-dB reduction of the relaxation oscillation peak. Some high-resolution laser spectroscopy measurements have been performed on the acetylene molecule by means of the tunable Yb–Er microlaser. Frequency locking and stabilization was achieved by both the fringe-side locking technique and the FM side-band technique, using different rovibrational lines of the C 2H 2. The beat note between two independently stabilized diode-pumped Yb–Er:glass lasers, operating at 1534.097 nm wavelength, yielded a long-term frequency stability of 170 kHz with an Allan standard deviation below 10 −10 for integration times between 10 ms and 1 s.

Lasing tests on new ytterbium–erbium laser glass pumped by neodymium lasers

Lasing tests on a new ytterbium–erbium glass designed for pumping by neodymium lasers are reported.

Low-threshold erbium glass minilaser

A new chromium ytterbium erbium laser glass LGS-Kh was used for the first time in minilasers emitting at 1.54 μm and characterized by a very low (less than 5 J) threshold and a relatively high (up to 1.7%) efficiency. An average output power of 0.7 W was obtained at a pulse repetition frequency of 7 Hz.