Simple Cavity Configuration Research Articles

Investigation of the Brillouin effect in highly nonlinear hafnium bismuth erbium doped fiber

AbstractThis paper demonstrates the generation of the Brillouin fiber laser (BFL) with 0.5 m long hafnium bismuth erbium doped fiber (HBEDF) as a hybrid gain medium. As the gain medium is pumped by a 980 nm laser diode at the power of 170 mW, a stable Stokes is observed at the output power of −2.96 dBm with Brillouin pump (BP) power of 3 dBm. The laser operates at wavelength shifted by 0.09 nm from the BP. To the best of the authors' knowledge, this is the first report of a compact BFL without employing any lengthy SMF, which features a simple cavity configuration.

Simultaneous oscillations of twelve wavelengths around 1.3 μm in quasi-CW Nd:YAG laser

In this work, a simple cavity configuration for simultaneous observation of twelve oscillating wavelengths around 1.3µm in a quasi-CW side pumped Nd:YAG laser is proposed and demonstrated experimentally. The experiment has been studied in free running condition and by placing a position tunable Brewster plate within a linear cavity where new wavelengths viz. 1318.71nm, 1338.14nm, 1338.16nm, 1338.18nm, 1338.21nm, 1338.23nm, 1338.25nm and 1338.27nm have been observed. By introducing a Brewster plate within the cavity it is possible to maintain almost equal spectral contributions around 1318nm and 1338nm wavelength’s regions at the highest as well as lowest pump power levels. The maximum average output power of 20W and 13.87W at slope efficiencies of 42.22% and 35.37% are obtained in both conditions respectively. In this work it is also possible to measure the average output powers around 1319nm and 1338nm regions simultaneously at different average pump powers. The experimental results indicate the higher and better stability of power contributions of observed oscillating wavelengths around 1.3µm. The beam quality factor varies from 1.11 to 1.44 with the rise in average pump power simultaneously. The proposed work may enhance the application of 1.3µm laser in spectroscopic field and tunable laser generation. Moreover, by difference frequency mixing within these closely spaced wavelengths this configuration may also be a good source of coherent THz generation.

Regenerative similariton laser

Self-pulsating lasers based on cascaded reshaping and reamplification (2R) are capable of initiating ultrashort pulses despite the accumulation of large amounts of nonlinearities in all-fiber resonators. The spectral properties of pulses in self-similar propagation are compatible with cascaded 2R regeneration by offset filtering, making parabolic pulses suitable for the design of a laser of this recently introduced class. A new type of regenerative laser giving birth to similaritons is numerically investigated and shows that this laser is the analog of regenerative sources based solely on self-phase modulation and offset filtering. The regenerative similariton laser does not suffer from instabilities due to excessive nonlinearities and enables ultrashort pulse generation in a simple cavity configuration.

Ultra-narrow linewidth single longitudinal mode Brillouin fiber ring laser using highly nonlinear fiber

In this letter, we demonstrate a single longitudinal mode (SLM) Brillouin fiber laser by using highly nonlinear fiber (HNLF) as the nonlinear medium in which the stimulated Brillouin scattering effect takes place. The first Stokes line is generated at a threshold power of 18 dBm with a wavelength shift 0.08 nm from the Brillouin pump. The signal-to-noise ratio of the first Stokes line is measured to be ∼58 dB. To the best of the authors’ knowledge, this is the first report of a 0.7 kHz ultra-narrow linewidth of an SLM Brillouin fiber laser, using HNLF as the nonlinear medium, which features a simple cavity configuration.

Direct production of high-power radially polarized output from a side-pumped Nd:YVO_4 bounce amplifier using a photonic crystal mirror

We produced a high power radially-polarized output directly from a diode-pumped Nd:YVO(4) bounce amplifier, using an autocloned photonic crystal mirror as an output coupler, with a simple cavity configuration. The radially-polarized output power of approximately 6 W was achieved, and a corresponding slope efficiency was estimated to be approximately 17 %. The output was characterized to be an ideal radially-polarized beam from its polarization distribution profiles. The output mode was not an eigenmode in the resonator. We discussed and clarified intra-cavity mode dynamics in terms of polarization distribution in the wavefront.

Direct production of high-power radially polarized output from a side-pumped Nd:YVO_4 bounce amplifier using a photonic crystal mirror

We produced a high power radially-polarized output directly from a diode-pumped Nd:YVO4 bounce amplifier, using an autocloned photonic crystal mirror as an output coupler, with a simple cavity configuration. The radially-polarized output power of ~6 W was achieved, and a corresponding slope efficiency was estimated to be ~17 %. The output was characterized to be an ideal radially-polarized beam from its polarization distribution profiles. The output mode was not an eigenmode in the resonator. We discussed and clarified intra-cavity mode dynamics in terms of polarization distribution in the wavefront.

A widely tunable dual-wavelength CW Ti:sapphire laser with collinear output

We report a collinear output and tunable dual-wavelength CW Ti:sapphire laser with a simple cavity configuration. The wavelength splitting range is easily tuned from 10 nm to 110 nm, which provides 56 THz bandwidth for terahertz generation. The total output power of two colors with the spatial mode of TEM(00) is between 700 mW and 300 mW, for small and large wavelength splittings, respectively, under 5 W argon-ion laser pumping.

Double-pass-pumped Tm:YAG laser with a simple cavity configuration

For a double-pass-pumped cw Tm:YAG laser, we developed a theoretical model, taking into account reabsorption loss and mode matching between the pumping light and the cavity mode. We also demonstrated that efficient operation can be obtained with a simple cavity configuration by using a dichroic output mirror, highly reflective at the pumping wavelength and partially reflective at the lasing wavelength. Experimental comparisons of this pumping method with single-pass pumping showed that the longitudinally double-pass-pumped Tm:YAG laser performs as well at room temperature as the single-pass-pumped laser performs at -10 degrees C.

Transform-Limited 30-fs Pulse Generation from a Diode-Pumped Kerr-Lens Mode-Locked Cr:LiSAF Laser

The generation of transform-limited 30-fs pulses from a laser-diode pumped, Kerr-lens mode-locked Cr:LiSAF laser is reported. Good mode-locking was achieved by use of a simple cavity configuration with a laser diode pumping source which had a separate section of a laser diode amplifier. The 30-fs optical pulse width was confirmed by use of an autocorrelator having little internal dispersion due to its composition of only reflecting mirror optics. A time-bandwidth product of 0.318 was obtained for the laser output pulse by assumption of a sech2 waveform.

Passive mode-locking through nonlinear polarization rotation in low-birefringence fibers

A numerical model for the generation of ultrashort soliton pulses from erbium-doped fiber ring lasers is presented. The model is used to study the pulse dynamics of a simple cavity configuration that uses a low birefringence fiber combined with crossed polarizers. Simulations show that stable pulses with a FWHM as short as 70 fs can be generated. It is also shown that coherent coupling may enhance mode-locking in a weakly linearly birefringent fiber under optimum operation conditions, and in certain cases a period doubling bifurcation occurs due to residual linear birefringence in the fibers.

Low-field microwave magnetoabsorption in manganites

We report the magnetic field dependence of microwave absorption at low fields (200 Oe), in thin film and bulk samples of La1−xBaxMnO3−z. We demonstrate, using a very simple cavity configuration, that the magnetic field sensitivity of the microwave response of the giant magnetoresistance materials offers possibilities of using such materials in devices operating at low fields. Low-field dc magnetization and ac resistivity measurements are also presented.