Dissipative soliton resonance mode-locked double clad Er:Yb laser at different values of anomalous dispersion

High-precision passive stabilization of a dissipative soliton resonance laser repetition rate based on optical pulse injection

I present what is believed to be the first demonstration of using the cross-phase modulation (XPM) effect to achieve high-precision, all-optical synchronization and stabilization of the pulse repetition rate of a dissipative soliton resonance (DSR) mode-locked (ML) fiber laser working in the 1.06 µm wavelength range. Nanosecond 1.55 µm Master oscillator pulses were injected into the Slave cavity of the DSR laser to induce the XPM effect and subsequently synchronize both repetition rates. When referencing the Master laser to a rubidium frequency standard, the fractional instability of the DSR ML laser pulse repetition rate reached 1.26 × 10-12 for 1000 s integration time. The locking range and stability of the XPM synchronization are experimentally verified under varying conditions and discussed in the paper.

Q-switching bifurcation dynamics of passively mode-locked lasers

We model Q-switched pulses in passively mode-locked lasers using the cubic-quintic complex Ginzburg-Landau equation (CGLE). We show that a wide set of parameters of this equation leads to Q-switched pulses of triangular shape that consist of a periodic sequence of evolving dissipative solitons. Bifurcation diagrams demonstrating various transformations of these pulses are calculated in terms of five major parameters of the CGLE. The diagrams show period doubling transformations as well as the transition to a chaotic evolution of the Q-switched pulses.

1.3 µm dissipative soliton resonance generation in Bismuth doped fiber laser

In this work, a Figure-9 (F9) bismuth-doped fiber laser (BiDFL) operating in the dissipative soliton resonance (DSR) regime is presented. The 1338 nm laser used a BiDF as the active gain medium, while a nonlinear amplifying loop mirror (NALM) in an F9 configuration was employed to obtain high energy mode-locked pulses. The wave breaking-free rectangular pulse widened significantly in the time domain with the increase of the pump power while maintaining an almost constant peak power of 0.6 W. At the maximum pump power, the mode-locked laser delivered a rectangular-shaped pulse with a duration of 48 ns, repetition rate of 362 kHz and a radio-frequency signal-to-noise ratio of more than 60 dB. The maximum output power was recorded at around 11 mW with a corresponding pulse energy of 30 nJ. This is, to the best of the author's knowledge, the highest mode-locked pulse energy obtained at 1.3 μm as well as the demonstration of an NALM BiDFL in a F9 configuration.

A Novel Low-Cost Synchronous/Asynchronous Microcontroller-Based Pulsed Laser

The development and implementation of continuous-wave (CW) or pulsed lasers has become essential in all areas of science and engineering. In the case of pulsed lasers, their emission period is commonly set up by the length of the laser cavity, which implies that it is necessary to replace the whole laser or modify the cavity to change the repetition rate. On the other hand, microcontrollers, capable of performing specific tasks saving size, cost and power consumption, have proven to be a powerful tool for various applications. To the best of our knowledge, we present a novel pulsed laser based on a very low-cost commercial microcontroller and a continuous-wave laser diode, where the pulse width and period are adjustable through a graphical user interface (GUI); besides, a new temporal asynchronous regime consisting of periodic packets of multiple pulses is produced. Pulses from 8 to 60 ms duration and with periods from 0.25 to 5 s are presented. These long optical pulses can be useful in certain applications where conventional pulses cannot be used due to their inadequate pulse width or period or intensity, such as simulating the neuronal activity of the brain or the development of neuromorphic hardware, where the response times are in the order of ms.

Single and dual-wavelength noise-like pulses with different shapes in a double-clad Er/Yb fiber laser

We report an experimental study of passive harmonic mode-locking in an all-fiber switchable dual-wavelength Er/Yb double-clad laser. The proposed scheme supports single- and dual-wavelength operation of mode-locked pulses with rectangular, h-like and trapezoidal shapes in a noise-like pulse regime. Single-wavelength emissions at λ₁ = 1545.1 and λ₂ = 1563.6 nm were obtained for pump power values of 9.42 and 6.31 W, achieving pulse durations of up to 18 and 11.8 ns, respectively. At an intermediary pump power of 7.5 W, dual-wavelength emission is obtained and pulses of around 3.59 ns are generated. Additionally, the transition dynamics until 4th-order harmonic mode-locking is also observed. Different laser operation regimes of fundamental and different orders of harmonic mode-locking, with rectangular, h-shaped or trapezoidal shaped pulses are obtained with the same laser configuration with simple and well-defined plates and pump power adjustments.

Chirp-adjustable square-wave pulse in a passively mode-locked fiber laser

A passively mode-locked fiber laser to generate chirp-adjustable square-wave pulses is reported. A simple chirp measurement system is designed to study the output chirp of the fiber laser. The results indicate that the chirp of the square-wave pulses in our fiber laser can be adjusted by the polarization controllers inside the cavity. Three typical chirp states, including random chirp, V-shaped chirp and linear chirp, are achieved. This kind of fiber laser cannot only help to further understand the characteristics of square-wave pulse but also serve as multifunction light source for potential applications.

Cavity-birefringence-dependent h-shaped pulse generation in a thulium-holmium-doped fiber laser

We report on a type of 2 μm h-shaped pulse generation in a thulium-holmium-doped fiber laser and experimentally investigate its cavity birefringence and pump power dependences. An asymmetric nonlinear optical loop mirror is employed as an artificial saturable absorber, which incorporates ∼52.7  m dispersion-shifted fiber and ∼3.8  m ultra-high numerical aperture fiber to enhance the nonlinearity. The h-shaped pulse shows both a polarization state (PS) and pump power related evolutions, even when randomly weak birefringence fibers are employed. By further incorporating different lengths of high birefringence polarization-maintaining fiber (PMF), i.e., introducing different amounts of linear cavity birefringence, much larger pulse tuning ranges can be realized. In particular, when the PMF is lengthened to ∼2.3  m through manipulating the PS, the achieved longest pulse duration of ∼318.14  ns can almost cover the whole repetition period of ∼323.96  ns, corresponding to a pulse duty circle of ∼98.2%, the largest ever reported from a fiber laser, to the best of our knowledge. We demonstrate the related characteristics in detail.

Pulse dynamics of dual-wavelength dissipative soliton resonances and domain wall solitons in a Tm fiber laser with fiber-based Lyot filter

We report on the first demonstration of dual-wavelength square-wave pulses in a thulium-doped fiber laser. Under appropriate cavity parameters, dual-wavelength dissipative soliton resonances (DSRs) and domain wall solitons (DWSs) are successively obtained. Meanwhile, dark pulses generation is achieved at the dual-wavelength DWSs region due to the overlap of the two domain wall pulses. The fiber-based Lyot filter, conducted by inserting PMF between an in-line PBS and a PD-ISO, facilitates the generation of dual-wavelength operation. The polarization-resolved investigation suggests that the cross coupling between two orthogonal polarization components in the high nonlinear fiber plays an important role in the square-wave pulses formation. The investigation may be helpful for further understanding the square-wave pulse formation and has potential in application filed of multi-wavelength pulsed fiber lasers.

Switchable generation of rectangular noise-like pulse and dissipative soliton resonance in a fiber laser

We report on the switchable generation of a rectangular noise-like pulse (NLP) and a dissipative soliton resonance (DSR) in a fiber laser with highly nonlinear effect at very low pump power. The NLP centered at 1530.5 nm demonstrates a new characteristic that its profile evolves gradually from rectangular shape to Gaussian-like shape with the increasing pump power. By appropriately manipulating the polarization controller (PC), the laser switches emit a DSR pulse centered at 1551.3 nm. The duration of the DSR could broaden from 17.4 ns to the cavity round trip time with increasing the pump power, while keeping the pulse profile and the intensity unaltered. This type of fiber laser may not only facilitate further investigations of the characteristics of NLP and DSR but also serve as a multi-functional optical source for potential applications.

Dissipative soliton resonance mode-locked all-polarization-maintaining double clad Er:Yb fiber laser

Our first demonstration of an all-PM fiber double clad erbium-ytterbium figure-8 laser mode-locked in a dissipative soliton resonance regime is presented. The laser generated µJ-level rectangular-shaped pulses with a maximum average output power of 1 W at 994 kHz repetition rate. The proposed configuration was characterized for two values resonator lengths - 44 and 205 m (total net-dispersion -0.9274 ps² and -4.3084 ps², respectively) to verify the possibility of non-complex tailoring of pulse parameters. The long-term stability of the all-PM configuration and self-starting of the mode-locking was experimentally confirmed by exposing the laser to forces of -5G to 7G magnitude on a vibration generator.

Multipulse dynamics under dissipative soliton resonance conditions

The stable multipulse emission from an erbium-doped mode-locked fiber laser in dissipative soliton resonance (DSR) regime is numerically and experimentally investigated. It shows that in the multipulse operation of DSR, all pulses have identical characteristics. The number of these pulses is determined by the initial conditions, and keeps constant with the growth of pump power. Experimental results match well with the theoretical simulations. In the experiment, we obtain as high as 86 dual-wavelength DSR pulses, which have the same characteristics and are equally spaced in the cavity. Since the pulses behave similarly to harmonic mode-locking (HML), we call this phenomenon HML under DSR. By properly adjusting the polarization controllers, other numbers of multipulse emission in DSR region can be observed, which confirms that the number of DSR pulses depends on the initial conditions.

1.2-W average-power, 700-W peak-power, 100-ps dissipative soliton resonance in a compact Er:Yb co-doped double-clad fiber laser

Mode-locked pulses in the dissipative soliton resonance (DSR) regime enable extremely high pulse energy, but typically have the limited peak power of <100  W and a nanosecond-long pulse duration. In this Letter, we demonstrate high-peak-power, ultrashort DSR pulses in a compact Er:Yb co-doped double-clad fiber laser. The linear cavity is simply formed by two fiber loop mirrors (FLMs) using a 50/50 optical coupler (OC) and a 5/95 OC. The 5/95 FLM with a short loop length of 3 m is not only used as the output mirror, but also acts as a nonlinear optical loop mirror for initiating high-peak-power DSR. In particular, the mode-locked laser can deliver ∼100  ps DSR pulses with a maximum average power of 1.2 W and a peak power as high as ∼700  W. This is, to the best of our knowledge, the highest peak power of DSR pulses obtained in mode-locked fiber lasers.