Vladimir A. Lazarev

Accuracy of sample material parameters reconstruction using terahertz pulsed spectroscopy

New experimental and theoretical results for the material parameter reconstruction using terahertz (THz) pulsed spectroscopy (TPS) are presented. The material parameter reconstruction algorithm was realized and experimentally implemented to study the test sample. In order to both verify the algorithm and to estimate the reconstruction accuracy, test sample material parameters obtained with the TPS were compared with the results of the same sample studying by the use of the backward-wave oscillator (BWO) spectroscopy. Thus, high reconstruction accuracy was demonstrated for the spectral range, corresponding to the BWO sensitivity and located between 0.2 and 1.2 THz. The numerical simulations were applied for determining the material parameter reconstruction stability in the presence of white Gaussian noise in TPS waveforms as well as fluctuations in the femtosecond (FS) optical pulse duration. We report a strong dependence of the inverse problem solution stability on these factors. We found that the instabi...

Ultra-short pulse generation in the hybridly mode-locked erbium-doped all-fiber ring laser with a distributed polarizer

We report for the first time to the best of our knowledge on the ultra-short pulse (USP) generation in the dispersion-managed erbium-doped all-fiber ring laser hybridly mode-locked with boron nitride-doped single-walled carbon nanotubes in the co-action with a nonlinear polarization evolution in the ring cavity with a distributed polarizer. Stable 92.6 fs dechirped pulses were obtained via precise polarization state adjustment at a central wavelength of 1560 nm with 11.2 mW average output power, corresponding to the 2.9 kW maximum peak power. We have also observed the laser switching from a USP generation regime to a chirped pulse one with a corresponding pulse-width of 7.1 ps at the same intracavity dispersion.

High-energy, sub-100 fs, all-fiber stretched-pulse mode-locked Er-doped ring laser with a highly-nonlinear resonator.

We report on ultra-short stretched pulse generation in an all-fiber erbium-doped ring laser with a highly-nonlinear germanosilicate fiber inside the resonator with a slightly positive net-cavity group velocity dispersion (GVD). Stable 84 fs pulses were obtained with a 12 MHz repetition rate at a central wavelength of 1560 nm with a 48.1 nm spectral pulse width (full width at half maximum, FWHM) and 30 mW average output power; this corresponds to the 29.7 kW maximum peak power and 2.5 nJ pulse energy obtained immediately from the oscillator.

Continuous-wave broadly tunable diode laser array-pumped mid-infrared Cr2+:CdSe laser

We demonstrate the operation of a room-temperature, solid-state, broadly tunable Cr-doped CdSe single-crystal continuous-wave laser. Longitudinal pumping with a continuous-wave diode laser array at 1.94 μm produced a broadband output of 280 mW at 2.6 μm with an incident power slope efficiency of 12%. With an intracavity Brewster-cut CaF2 prism, we tuned the Cr2+:CdSe laser from 2.45 to 3.06 μm with a resolution of 10 nm and an output power up to 55 mW.

Visible supercontinuum generation in large-core photonic crystal fiber with high air-filling fraction

We demonstrate new experimental results for visible supercontinuum generation in large-core photonic crystal fiber with high air-filling fraction. Supercontinuum is generated by picosecond pulses from a passively mode-locked Yb:KGW laser. A smooth supercontinuum generation near 800 nm is achieved using 4.5 m long large-core photonic crystal fiber even with 6 mW average coupled power. These results are of interest in high power white light sources and have potential applications in precise frequency metrology and spectroscopy. The data obtained could be used also in theoretical studies of nonlinear interaction in large-core photonics crystal fibers with high air-filling fraction.

Hybrid mode-locked ultrashort-pulse erbium-doped fiber laser

One of the implementations of fs-laser with CNT-film for mode-locking is considered. Scheme of single-pulse, self-starting, stable mode-locked laser generation by appropriate polarization controllers adjustment is suggested. The mechanism of cavity length stabilization for a femtosecond fiber laser based on the pump source modulation is considered. Bandwidth of the feedback frequency stabilization system based on pump source modulation method is defined.

Stable Similariton Generation in an All-Fiber Hybrid Mode-Locked Ring Laser for Frequency Metrology

Ultrashort pulse lasers constitute an important tool in the emerging field of optical frequency metrology and are enabling unprecedented measurement capabilities and new applications in a wide range of fields, including precision spectroscopy, atomic clocks, ultracold gases, and molecular fingerprinting. We demonstrate the generation of stable 127-fs self-similar pulses at a central wavelength of 1560 nm with 7.14-mW average output power. Similariton lasers have a low repetition rate deviation in the averaging time interval 1-1·103 s, a low relative intensity noise -120 dBc/Hz (30 Hz to 10 kHz), a narrow single comb line width of 32 kHz, and high reliability. Thus, such lasers are highly promising for further development of the stabilized combs and open up a robust and substantially simplified route to synthesizing low-noise microwaves.

Structural monitoring system with fiber Bragg grating sensors: implementation and software solution

We present a structural health monitoring system for nondestructive testing of composite materials based on the fiber Bragg grating sensors and specialized software solution. The developed structural monitoring system has potential applications for preliminary tests of novel composite materials as well as real-time structural health monitoring of industrial objects. The software solution realizes control for the system, data processing, and alert of an operator.

Testing of Cr:ZnSe Laser with Intracavity Methane Cell in 77-300 K Temperature Range

The mid-IR cw tunable solid state two-mode Cr²⁺:ZnSe laser with intracavity methane cryocell was developed. The laser was applied for sub-Doppler spectroscopy of (υ₁+υ4) vibrational-rotational band of methane and observation of narrow resonances of saturated dispersion at λ = 2.36 μm. The new technique of low pressure methane gas cooling was used instead of liquid nitrogen “jacket” design applied in our previous work. Parameters of saturated dispersion resonances were estimated in 77-300 K temperature range. The experiments confirmed that laser with the new “dry cooled” methane cell has prospectives for reaching a short-term frequency stability at the level of 10^-15-0^-16 and can be used as a compact device.

Tunable CW Solid-State Mid-IR Cr 2+ :CdSe Single Crystal Laser with Diode Laser Array Pumping

We demonstrate the first Cr2+:CdSe single crystal laser with diode laser array pumping. Laser efficiency of 12% with output power of 280 mW was obtained. Tunable CW operation was observed in 2450 - 3060 nm range.