Physics-based deep learning for modeling nonlinear pulse propagation in optical fibers.

A physics-based deep learning (DL) method termed Phynet is proposed for modeling the nonlinear pulse propagation in optical fibers totally independent of the ground truth. The presented Phynet is a combination of a handcrafted neural network and the nonlinear Schrödinger physics model. In particular, Phynet is optimized through physics loss generated by the interaction between the network and the physical model rather than the supervised loss.

Focus issue introduction: Advanced Solid-State Lasers 2020.

This Joint Issue of Optics Express and Optical Materials Express features 15 articles written by authors who participated in the international online conference Advanced Solid State Lasers held 13-16 October, 2020. This review provides a summary of the conference and these articles from the conference which sample the spectrum of solid state laser theory and experiment, from materials research to sources and from design innovation to applications.

Advanced Solid-State Lasers 2019: focus issue introduction.

This joint issue of Optics Express and Optical Materials Express features 17 state-of-the art articles written by authors who participated in the international conference Advanced Solid-State Lasers held in Vienna, Austria, from September 29 to October 3, 2019. This introduction provides a summary of these articles that cover numerous areas of solid-state lasers from materials research to sources and from design to experimental demonstration.

Focus issue introduction: advanced solid-state lasers.

This joint issue of Optics Express and Optical Materials Express features 28 state-of-the-art articles written by authors who participated in the international "Advanced Solid State Lasers" conference, held in Boston November 4-8, 2018. This review provides a summary of these articles that cover the spectrum of solid state lasers from materials research to sources and from design innovation to applications.

Feature issue introduction: Advanced Solid-State Lasers 2017.

The Advanced Solid State Lasers 2017 Conference (ASSL) was held from October 1 to 5, 2017. It was an extraordinary conference at the Nagoya Congress Center in Nagoya, Japan. ASSL 2017 again suggested an impressive platform where miscellaneous perceptions with a variety of approaches to optics, photonics, sensing, laser technology, laser systems, and solid state lasers were presented.

Effective photodarkening suppression in Yb-doped fiber lasers by visible light injection.

Al-silicate fibers have excellent manufacturing quality. Unfortunately, high-Yb doping concentration may be limited by severe losses induced by photodarkening phenomenon. In this paper we demonstrate for the first time that Al-silicate Yb-doped fibers with high-inversion and doping concentration above 1 wt% can be successfully used by implementing a simple optical bleaching scheme.

Mitigation of photodarkening phenomenon in fiber lasers by 633 nm light exposure.

In this work, the influence of photodarkening (PD) and photobleaching (PB) on the lasing features of the ytterbium-doped aluminosilicate fiber lasers is examined. Simultaneous PD and PB with 633 nm irradiation was monitored at the lasing wavelength of 1070 nm and compared with individually caused PD and PB effects. The variation of laser threshold and slope efficiency was reported.

Novel approach towards cross-relaxation energy transfer calculation applied on highly thulium doped tellurite glasses.

In this paper we calculated, for the first time to the best of our knowledge, the cross relaxation parameter of Tm(3+) ions in tellurite glasses over a wide range of concentrations: from 0.36 mol% up to 10 mol%. A new measurement approach based on emission spectra monitoring is proposed.

Temporal evolution and correlation between cooperative luminescence and photodarkening in ytterbium doped silica fibers.

The present work describes photodarkening from the viewpoint of cooperative luminescence. The temporal evolution of both effects was measured simultaneously by means of ytterbium doped aluminosilicate fibers for concentrations up to 1.8 wt% Yb3+.

Single-mode and high power waveguide lasers fabricated by ion-exchange.

We report on a single-end diode-pumped waveguide laser providing output power in excess of 20 mW with 17% slope efficiency in robust single longitudinal and transverse mode operation at 1533.5 nm. The active medium was an Er:Yb-doped waveguide only 9-mm long fabricated by Ag-Na ion-exchange in a phosphate glass.

High-repetition-rate picosecond pulse generation at 1.5 microm by intracavity laser frequency modulation.

We propose and experimentally demonstrate generation of transform-limited pulse trains at a 2.5-GHz repetition rate from a frequency-modulated erbium-ytterbium bulk glass laser by using an intracavity lithium niobate phase modulator and an external fiber Bragg grating filter. Light pulses with durations tunable from 40 to 80 ps and 0.

5-GHz repetition-rate dual-wavelength pulse-train generation from an intracavity frequency-modulated Er-Yb:glass laser.

We report the experimental demonstration of nearly transform-limited dual-wavelength pulse trains at a 5-GHz repetition rate that were generated by spectral filtering of an intracavity 2.5-GHz frequency-modulated Er-Yb bulk-glass laser operating at the 1533-nm wavelength. Highly stable dual-wavelength pulse trains with approximately 165-GHz frequency separation, approximately 48-ps pulse duration, and approximately 1-mW average single-mode fiber-coupled power were obtained.

Suppression of intensity noise in a diode-pumped Tm-Ho:YAG laser.

We investigate the intensity noise induced by pump-power fluctuations in a diode-pumped single-frequency codoped Tm-Ho:YAG laser and we measure, in the frequency domain, the corresponding transfer function. Good agreement between the measured transfer functions and the theoretical prediction is found. A relative intensity-noise level of ~- 110 dB/Hz from ~1 kHz to the relaxation-oscillation frequency, with complete suppression of the relaxation-oscillation peak, is achieved by use of a suitable optoelectronic feedback circuit.

Femtosecond micromachining of symmetric waveguides at 1.5 microm by astigmatic beam focusing.

We report on a new spatial beam-shaping approach for fabrication of waveguides with a circular transverse profile by femtosecond laser pulses, using an astigmatic beam and controlling both beam waist and focal position in the tangential and sagittal planes. We apply this technique to write single-mode active waveguides at 1.5microm in Er:Yb-doped glass substrates.

Nonlinear dynamics induced by burst amplification in optically gain-stabilized erbium-doped amplifiers.

Optical burst amplification in a gain-stabilized amplifier may generate complex gain dynamics with nonlinear behavior. This phenomenon is thoroughly investigated by using a theoretical model and dedicated experiments. Design guidelines for optimized devices avoiding optical burst transmission impairments are proposed.

1.5 mum single longitudinal mode waveguide laser fabricated by femtosecond laser writing.

A compact and efficient single longitudinal mode laser based on a femtosecond laser written waveguide is demonstrated. A maximum output power exceeding 50 mW was measured in single longitudinal and transverse mode operation, with 21% slope efficiency. The active waveguide was fabricated on erbium-ytterbium-doped phosphate glass by direct writing with femtosecond laser pulses from a diode-pumped cavity-dumped oscillator.

Efficient Erbium-doped waveguide amplifier insensitive to power fluctuations.

We describe an efficient erbium-doped waveguide amplifier insensitive to output power variation by means of optical gain clamping. Output power suitable for metro applications and gain flatness over full C-band are demonstrated. We also show that this technology is suitable for transparent WDM ring network.

C-band waveguide amplifier produced by femtosecond laser writing.

An optical waveguide amplifier fabricated on erbium-ytterbium-doped phosphate glass by direct femtosecond laser writing is demonstrated. The waveguides are manufactured using 1040-nm radiation from a diode-pumped cavity-dumped Yb:KYW oscillator, operating at a 885 kHz repetition rate, with a 350 fs pulse duration. Peak internal gain of 9.

Er:Yb-doped waveguide laser fabricated by femtosecond laser pulses.

Laser action is demonstrated in a 20-mm-long waveguide fabricated on an Er:Yb-doped phosphate glass by femtosecond laser pulses. An output power of 1.7 mW with approximately 300 mW of pump power coupled into the waveguide is obtained at 1533.

Optical waveguide writing with a diode-pumped femtosecond oscillator.

Optical waveguide writing is demonstrated by means of a diode-pumped cavity-dumped Yb:glass femtosecond laser oscillator with a pulse energy of 270 nJ at a 166-kHz repetition rate. Waveguides realized on an Er:Yb-doped phosphate glass are almost perfectly mode matched to standard single-mode fibers at 1.55 microm and show a 1.

Widely tunable continuous-wave diode-pumped 2-microm Tm-Ho:KYF4 laser.

Continuous-wave laser action at approximately 2 microm is demonstrated in a Tm-Ho:KYF4 single crystal at room temperature. Crystal growth, spectroscopic measurements, and laser results are presented. An output power in excess of 250 mW is obtained with a tuning range of 99 nm, the largest ever published, to our knowledge, for Tm-Ho in any crystalline host.

Widely tunable fiber-coupled single-frequency Er-Yb:glass laser.

A fiber-coupled tunable Er-Yb:glass minilaser is presented with output power of 40 mW. The laser can be stepwise tuned in single-frequency operation from 1530 to 1560 nm by compressing a fiber Bragg grating that provides selective feedback. Constant output power (fluctuation < 0.