Analysis of the Passive Stabilization Methods of Optical Frequency Comb in Ultrashort-Pulse Erbium-Doped Fiber Lasers

Abstract

In this review paper, we describe the current state of the art to stabilize the output radiation of ultrashort-pulse (USP) fiber lasers and analyze passive methods to reduce the magnitude of fluctuations in the amplitude–frequency noise of output radiation. Regarding main noise characterization in mode-locked fiber lasers, we further consider the influence on laser operation of primary generation regimes starting up in cavities, such as solitons, stretched pulses, similaritons, and dissipative solitons. Then, we proceed to analyze the external and internal factors that affect the stability of the output radiation characteristics depending on the mode-locking mechanism and the resonator scheme.

High-Density Well-Aligned Single-Walled Carbon Nanotubes for Application as a Saturable Absorber with a High-Pass Filter Effect in an Erbium-Doped Ultra-Short-Pulse Fiber Laser

“…It is worth noting that the second type of active fiber performs two main functions. First, it simplifies shifting the total dispersion of the resonator to a strongly positive region for stable generation of chirped pulses. , Second, it acts as an additional spectral filter, absorbing low-intensity spectral components and enhanced spontaneous radiation in the region of 1530 nm. Due to this, a strong broadening of the optical spectrum characteristic of chirped pulses was prevented and the influence of ASE on the generated radiation was reduced .…”

“…Moreover, the greatest interest has been concentrated on increasing the stability of generation. To date, most of the noise processes have been well studied by scientific groups and various methods have been developed to minimize them. , The amplitude stability of USP, represented by the level of relative intensity noise (RIN), is a key parameter to estimate the stability of a USP fiber laser, and the reduction of the RIN level is an active field of investigation especially in analog to digital devices and optical communications. , Also, the reduction of RIN guarantees a low-level of other noises, such as timing jitter and comb-line frequency noise …”

“…The key point is the variability of the methods used to eliminate different types of noise components in ultra-short-pulse fiber lasers. In general, amplitude–frequency stabilization methods are divided into passive and active methods. , Although, active methods allow the most effective elimination of noise components, passive methods remain relevant due to their ease of implementation, low cost, and compactness, which is a significant advantage for applications with weight restrictions and overall …”

“…Thus, by controlling the length of the fiber cavity with piezoceramic coils, the pulse repetition rate can be stabilized, and the intensity noise is reduced when the average output power of the study is fed back to the pump driver . Passive stabilization methods address the more fundamental causes of noise and are based on optical principles . When talking about passive methods to reduce intensity noise, saturable absorbers play a significant role not only in the formation of mode-locking but also in the stabilization of output pulse characteristics. − To date, in order to achieve a stable mode-locking in USP lasers, various SAs have been developed such as SA based on the nonlinear polarization evolution (NPE), − as well as SESAM saturable absorbers, carbon nanotubes, ,, and films of transition metal dichalcogenides. − Furthermore, it is especially worth highlighting hybrid mode-locking methods, which means the use of two saturable absorbers in the same cavity, for example, the use of NPE and carbon nanotubes SA .…”

“…11,12 Also, the reduction of RIN guarantees a low-level of other noises, such as timing jitter and comb-line frequency noise. 13 The key point is the variability of the methods used to eliminate different types of noise components in ultra-shortpulse fiber lasers. In general, amplitude−frequency stabilization methods are divided into passive and active methods.…”