Dmitriy Shelestov

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.

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.

Adaptation of the Er-Yb microchip laser for use in phase-sensitive optical time domain reflectometry

We report on the experiments related to the Er-Yb microchip laser setup with fiber diode pumping. The main goal is a new radiation source for the use in the phase-sensitive optical time domain reflectometry (φ-OTDR) development.

Comb characterization of Erbium All-fiber Hybrid Mode-locked ultra-short pulse Ring laser for Frequency Metrology

Stable 92.6 fs dechirped self-similar pulses were obtained at 1560 nm with 11.2 mW average output power. Similariton laser has low repetition rate deviation at 1 - 103 s, a single comb linewidth of 110 kHz and high reliability, which makes it promising for further development of the stabilized comb.

Er:Yb phosphate glass laser with nonlinear absorber for phase-sensitive optical time domain reflectometry

A novel laser for phase-sensitive optical time-domain reflectometry (Φ-OTDR) is presented. The advantages of a compact solid-state laser are listed, current problems are shown. Experiments with a microchip single-optical-element laser, from setup construction to usage in Φ-OTDR system, are presented. New laser scheme with two-photon intracavity absorber is suggested and its advantages are described.

Comb Peculiarities of Dispersion-Managed Solitons in a Hybrid Mode-Locked All-Fiber Ring Laser

We studied the optical comb peculiarities of the ultra-short dispersion-managed soliton generation in an erbium-doped all-fiber ring laser hybrid mode-locked with carbon:boron nitride single-walled nanotubes in the co-action with a nonlinear polarization evolution. A stable low-intensity-noise optical comb was obtained with a narrow single comb linewidth of 18.1 kHz based on dechirped 90-fs pulses with a repetition rate of 42.22 MHz, a spectral pulse width of 56 nm, and an average output power of 16.7 mW corresponding to 4.4-kW maximum peak power and 0.4-nJ pulse energy.

Stability peculiarities in the stretch pulse hybrid mode-locked erbium-doped all-fiber ring laser

Ultrashort pulse (USP) fiber lasers have become one of the most important instruments in various fields of science and industry during two past decades. A number of applications requires stability of pulse duration, repetition rate and low intensity noise of an USP source. For example, stabilization of this parameters is in great demand in frequency metrology field, dual comb spectroscopy, THz pulse spectroscopy and etc. It should be noted, that hybrid Mode-locking (ML) for USP generation have attracted a great attention due to their capabilities of enhancing pulse quality and providing reliable ML startup by taking advantage of a co-action of two saturable absorbers (SA) - a slow SA such as SESAM, carbon nanostructures or graphene, and a fast absorber based on nonlinear polarization evolution (NPE) effect. Recently Carbon:Boron Nitride Single-Walled Nanotubes(C:BNNTs) SA is proved to be reliable absorber with excellent saturation parameters for erbium-doped fiber laser ML. In this paper we have obtained and measured stability of stretch pulse generation in the hybrid ML erbium-doped all-fiber ring laser by using C:BNNTs SA in the co-action with NPE effect. We have managed to realize two different types of stable single-pulse, self-starting stretch pulse generation at a repetition frequency of 42.2MHz with S/N ratio ~ 63 dB. Note, that the total intracavity group velocity dispersion β2 was -0.021 ps2 at 1550 nm. Obtained sech2-type spectrum has a FWHM of ≈ 4nm at the output average power of 16.7mW and the Gauss-type spectra has a FWHM of ≈ 56 nm at the same output power. Pulse width measured by intensity autocorrelator is 650 fs for both USP generation regimes. Note, that the time-bandwidth product for the sech2 pulse is TBP=Δv × τ min ≈ 0.322 and for the Gauss pulse TBP ≈ 4.45 (typical TBP for a Gauss pulse ≈ 0.44). Thus, the obtained sech2 pulse is close to the bandwidth-limit (TBP ≈ 0.315 for a classical soliton). It should be noted, that minimal Gauss pulse width (up to sub-100 fs duration) can be achieved simply by proper fiber length control at the laser output.

All-fiber hybridly mode-locked similariton ring laser for frequency metrology

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 low repetition rate deviation in the averaging time interval 1-1·103 s, a low relative intensity noise -125 dBc/Hz, 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.

Note: Improved technique for ultrashort lasers pulse width stabilization

We have developed an improved pulse width stabilization method based on the second harmonic generation (SHG) technique using the relationship between pulse width, input intensity, and SHG intensity. On the basis of an analysis of the improved method accuracy, we then proposed a novel processing algorithm, which allowed us to increase the accuracy of pulse width stabilization to 1.2%. We applied this method to a picosecond Yb-doped fiber laser, which offers pulse widths ranging from 10 to 14 ps. We have demonstrated, for what is believed to be the first time, pulse width stabilization of this laser with an absolute error of less than 200 fs.