Optomechanical interaction in fibre lasers with micro-optomechanical resonance structures

Abstract

We report the results of studies of fibre lasers with passive modulators based on light-excited micro-optomechanical resonance structures (micro-oscillators). It is shown that in fibre lasers based on active fibres doped with rare-earth elements (Er, Er/Yb, Yb, Nd), the optomechanical interaction of laser radiation with micro-oscillators of various types (fibre-optic, microvolume) leads to self-oscillations of the characteristics of laser radiation at frequencies of relaxation oscillations and intermode beats synchronised with the frequencies of elastic eigenoscillations of micro-oscillators. It is found that in an ultra-long erbium – ytterbium fibre laser with a nonlinear mirror based on a microcantilever, laser photothermal excitation of the second mode of elastic transverse oscillations of the microcantilever makes it possible to perform passive mode locking exclusively due to Q-switching of the laser cavity. Pulsed lasing with a controlled repetition rate (∼76 kHz), a pulse duration of 2 – 5 μs and an output energy of 0.1 μJ per pulse is implemented. Based on a simplified physical model of the indicated fibre lasers with micro-oscillators, we have developed an approximate mathematical model describing the regimes of passive mode locking of fibre lasers with micro-oscillators that play the role of mirrors with a nonlinear reflection coefficient in the laser cavity. The prospects for the development and application of the considered laser systems are discussed.

Influence of the structure of the wavefront of laser radiation on synchronous self-oscillations in fiber lasers with micro-optomechanical resonators

“…(micro-optomechanical resonators, MOMR) provide an opportunity to implement novel and promising laser operation regimes with unique characteristics of radiation [1][2][3][4]. The laser excitation of elastic oscillations in micro-oscillators in fiber lasers (FL) with micro-oscillators allows one to implement synchronous self-oscillation (SSO) regimes with the radiation parameters modulated at frequencies close to the eigenfrequencies ( f ) of elastic MOMR oscillation modes: F = (1 + χ) f , χ ≪ 1 [5]. This may be used to stabilize the pulse frequency in fiber pulsed laser sources (similar to " quartz' stabilization in radio engineering) and may serve as a basis for the design of a new class of resonance fiber-optic sensors [6,7].…”

A multi-frequency synchronous self-oscillations in fiber lasers with optomechanical microoscillators

“…Along with this, the optical radiation interaction with several microoscillators simultaneously induces a number of new interesting phenomena [2] enabling expansion of the application area of such systems. In recent years, a reasonable continuation of these studies, namely, laser optomechanics connected with investigating the interaction between the laser radiation and OMO in active (laser) resonators was significantly developed [3][4][5]. Taking into account the laser dynamics specific features, it is possible to implement in them different−type internal resonances essentially defining the laser radiation generation modes and characteristics.…”

“…In this connection, especially interesting are fiber lasers (FL) possessing, along with unique specific features, a great variety of dynamic modes [6]. In the FL−OMO laser systems [5], for instance, under the resonance conditions ( f ≈ f rel is the FL relaxation oscillations frequency), synchronous self−oscillations (SO) are possible; they provide modulation of the amplitude, frequency, and polarization of the generated radiation with the OMO elastic oscillation frequency F = (1 + α) f , α ≪ 1. In view of the elastic oscillation modes dependence on external impacts upon OMO, this opens opportunities for creating FL with a controllable combined modulation of the radiation parameters, as well as self−generation fiber−optic sensors with a wide dynamic range and high measurement accuracy [1,7,8].…”

“…Three-, four-and five-frequency modes SO(3)−SO (5) were obtained using the group I microbeams and broadband reflectors as M 0 . Fig.…”

“…In this case, the spectrum is also continuous. Here there are three sidelobes (pulses) within the envelope period T (5) ≈ ( I 5 ) −1 ≈ 4 ms. Noteworthy is high sensitivity of SO(4) and, especially, of SO (5), to perturbations of the system, for instance, of parameters (l 0 , θ), which results in SO quenching and unstable " spike" modes with the P s (t) envelope in the form of random groups of pulses with different amplitudes and lengths. This is probably caused by an error in the OMO modes synchronization due to the random phase " failures" .…”