Dispersive Ring Cavity Research Articles

1 MHz Akinetic Dispersive Ring Cavity Swept Source at 850 nm

A fast dual mode-locked akinetic optical swept source at 850 nm central wavelength is presented using a dispersive cavity. We demonstrate that single mode fiber can be successfully used as dispersive element to induce mode locking. A first locking condition is imposed by driving the optical gain at a high frequency, to induce mode locking, while a second locking condition involves sweeping at a rate close to resonance value. In this regime, using the same fiber length in the loop, sweeping rates of 0.5 MHz and 1 MHz are demonstrated with proportional reduction in the tuning bandwidth. The axial range of the swept source was evaluated by scanning through the channeled spectrum of a Michelson interferometer.

Dual-mode-locking mechanism for an akinetic dispersive ring cavity swept source.

A fast dual-mode-locked akinetic optical swept source in the 1550-nm wavelength band is presented that is tested up to a sweep rate of 797 KHz. It comprises a voltage-controlled oscillator-driven wideband semiconductor optical amplifier (SOA) along with a dispersion compensation fiber, in a ring laser configuration. A Faraday rotating mirror is employed in the cavity as a reflective element in order to achieve better polarization control. By driving the SOA at a high-MHz-frequency value multiple of the resonant frequency f(R), equal to the inverse round trip time, a first-mode locking mechanism is imposed. A second locking mechanism consists in sweeping the radio frequency of the locking signal at a rate slightly detuned from f(R). A dynamic linewidth of 0.8 nm is assessed by measuring the decay of interference signal strength versus optical path difference in a Mach-Zehnder interferometer.

Versatile Swept Source With Adjustable Coherence Length

An electronically controlled optical swept source at 1550 nm using mode locking in a dispersive ring cavity is described. Active mode-locking was achieved by directly modulating the current of a semiconductor optical amplifier (SOA) used as a gain medium. In the static regime, parameters such as linewidth, tuning bandwidth, and contrast were measured, whereas the axial range was determined dynamically. Two types of fiber, dispersion compensation and single mode, are employed in the laser ring cavity. It is demonstrated that the relative lengths of the two types of fiber have little effect on the linewidth, whereas more control on the linewidth is obtained via the frequency of the signal driving the SOA. Linewidths less than 60 pm and over 1 nm were measured in the static regime while driving the SOA at 50-500 MHz. The narrowest linewidths were achieved where the proportion of dispersion compensation fiber in the cavity was 80%-90% of the total length. The optical source is developed to respond to the demands of several optical coherence tomography applications that do not necessarily need long coherence length swept sources. © 2014 IEEE.

Simple technique for alignment of a dispersive ring laser cavity

A simple technique for the alignment of a dispersive ring cavity consisting of a reflection-grating and two mirrors is described. Lasing on different rotational–vibrational transitions of CO 2 molecule is achieved in the ring configuration.

Stable multipulse states in a nonlinear dispersive cavity with parametric gain.

Existence of stable trains of weakly overlapping solitary waves with phase alternation is predicted in a nonlinear dispersive ring cavity with parametric amplification. It is shown that the breakup of the phase invariance of the wave equation induced by the parametric interaction is effective in damping any internal oscillations of the soliton lattice due to soliton interactions. \textcopyright{} 1996 The American Physical Society.

Polarization multistability and instability in a nonlinear dispersive ring cavity

We study the role of polarization in modulational instabilities in a synchronously pumped ring resonator that is filled with an isotropic nonlinear dispersive medium. To describe nonlinear propagation of the polarized field through the ring, we introduce two coupled driven and damped nonlinear Schrödinger equations. These equations, which result from averaging propagation and boundary conditions over each circulation through the ring, permit a simple stability analysis. This analysis predicts polarization multistability in the steady state as well as the emergence of stable pulse trains whose polarization state is either parallel or orthogonal to a linearly polarized synchronous pump beam. The analytical predictions are confirmed and extended by numerical simulations of polarized wave propagation in the cavity.

Suppression of interactions in a phase-locked soliton optical memory

A perturbative and numerical analysis reveals the conditions for suppressing the interaction between adjacent phase-locked solitons in a soliton optical memory. This may permit the permanent storage of a soliton bit pattern in a diffractive or dispersive ring cavity.

Dissipative modulation instability in a nonlinear dispersive ring cavity

We investigate the modulational instability in a synchronously pumped nonlinear dispersive ring cavity. The infinite-dimensional Ikeda map which describes the evolution of the field in the cavity is reduced to a partial derivative equation which allows for analytical developments. We show that, owing to the dissipative nature of the problem, the physics of modulational instability in the ring is fundamentally different from the usual modulational instability in a nonlinear dispersive fiber. In particular, we predict the formation of stable temporal dissipative structures for both the normal and the anomalous dispersion regime of the fiber.

Modulational instability oscillation in nonlinear dispersive ring cavity.

Periodic-intensity self-oscillation caused by modulational instability is observed for the first time in a nonlinear dispersive fiber ring cavity. The oscillation stops immediately when the phase coherence is disturbed by cavity detuning. It is found that a noninstantaneous response of the nonlinear index competes with the modulational instability gain and produces asymmetrical Stokes sidebands.