Fiber Optic Resonator Research Articles

Continuous-wave driving elucidates the desynchronization dynamics of ultrashort dissipative Raman solitons generated in dispersive Kerr resonators.

Phase-coherent pulsed driving of passive optical fiber resonators enables the generation of ultrashort dissipative Raman solitons with durations well below 100 fs. The existence and characteristics of such solitons critically depend on the desynchronization between the pulsed driving source and the resonator round trip time, yet the full mechanism through which these dependencies arise remains unclear. Here, we numerically demonstrate that Raman solitons can exist even under conditions of continuous-wave (CW) driving, and by numerically examining the existence and characteristics of Raman solitons under such conditions, we elucidate the role of desynchronization in pulse-driven systems. In addition to providing new insights into the existence and characteristics of ultrashort Raman solitons, our analysis yields a qualitative explanation for the range of desynchronizations over which the solitons can exist.

Single-longitudinal-mode lasing based on enhanced scattering in eccentric-hole microstructured optical fiber resonators

In this paper, we propose a dual-core eccentric-hole fiber (DCEHF) microresonator to achieve single-longitudinal-mode (SLM) laser emission based on enhanced pump light field induced by scattering effect of the two fiber cores. The directional dependences of the scattered pump field distribution on incident angle as well as overlap integrals between scattered pump light fields and WGMs have been theoretical investigated, and the calculation results show that when the incident angle of the pump light is close to 180°, significant discrepancies would occur in the overlap integrals between WGMs and the scattered field. And consequently, specific mode having the largest overlap integral would outperform through the mode competition process to excite SLM lasing. We have experimentally obtained SLM lasing emission when the DCEHF-based microresonator is rotated by 206°, which is in good accordance with our calculation results. Additionally, experimental observation of the output laser spectrum shows that the proposed fiber microcavity supports highly stable SLM laser emission. The proposed microresonator based on DCEHFs possesses several desirable merits such as compact size, good laser stability, single-mode operation, and good compatibility with existent fiber-optic systems, which make it a good candidate for applications as functional photonic device in future micro-optics systems.

МОДАЛЬНЫЙ АНАЛИЗ ОПТОВОЛОКОННОГО РЕЗОНАНСНОГО ПЬЕЗОЭЛЕКТРОЛЮМИНЕСЦЕНТНОГО ДАТЧИКА ДАВЛЕНИЯ

An electro-mechanical mathematical model of the functioning of an optical fiber resonance piezoelectroluminescent (RPEL) sensor with an external nonlinear elastic buffer layer has been developed. The sensor is designed to measure the distribution spectrum along the length of the dynamic and/or static pressure sensor using a resonant diagnostic method based on the results of measuring the amplitude spectrum of the intensity of the resulting light flux at the output from the fiber of the sensor. The numerical values of the frequency characteristics (- these are the proportionality coefficients for the informative relationship "pressure/resonance frequency") of the optical fiber RPEL sensor, which are used in the algorithm for finding the pressure spectrum, for different (first six) modes of vibration, are determined.

Estimation of the dynamic range of the angular velocity sensor based on a fiber-optic resonator

In the work, a fiber-optic resonator (FOR) was studied, which is used as a sensitive element of the angular velocity sensor. The measured operating parameters of the RVO are given and the dependence of the resonant frequency shift on the angular velocity is found. The developed layout made it possible to measure the minimum sensitivity to the angular velocity of this resonator and to evaluate the maximum measurement range. An estimate of the angular velocity measurement range gives values from minus 600,000 °/s to minus 10 °/s and from 10 °/s to 600,000 °/s.

Fiber Optic Resonators for Angular Rate Sensors

Fiber Optic Resonators for Angular Rate Sensors

Characteristics of various sensor devices for a miniature resonant optical gyroscope

Subject of study. Using a ring resonator as an example, this paper describes the general operating principle for optical resonators, the characteristics of such resonators, and the relationship between resonator quality factor Q and gyroscope sensitivity. Several sensor devices (optical resonators) were compared for use in the development of a miniature resonant optical gyroscope. These optical resonators were of three different types: a fiber-optic resonator, a whispering gallery mode resonator, and an integrated optical resonator ring. Methodology. The fiber-optic resonator consists of two fiber-optic splitters spliced together, the whispering gallery mode resonator consists of a three-dimensional dielectric structure in which whispering gallery modes are excited, and the integrated optical resonator ring consists of an optical waveguide and closed loop mounted on a common substrate. The characteristics of the high-Q(Q=106−109) whispering gallery mode resonators and fiber-optic resonators were measured using a narrow-band scanning laser and an oscillograph. A simpler approach, with a broadband laser source and an optical spectrum analyzer, was used for the low-Q(Q<106) integrated optical resonators. Main results. Values of Q=5.2×108, Q=4.3×106, and Q=1.1×104 were obtained for a MgF2 disk resonator, fiber-optic disk resonator, and integrated optical resonator, respectively. Practical significance. The whispering gallery mode resonator turns out to be the most promising of these sensor devices since it has the highest Q and the highest accuracy for angular velocity measurements. Fiber optic resonators are competitive but are more sensitive to temperature and external mechanical effects. Integrated optical resonators have the advantage of miniaturization and the ability to include temperature stabilization components and components that provide resistance to mechanical effects.

Determination of induced birefringence in a fiber-optic resonator from the frequency difference between main and additional resonance peaks

When radiation propagates in an optical ring resonator, apart from the main peaks, additional peaks are observed. It is known that the strain of optical fiber induces birefringence. Assuming that an additional peak is associated with the main peak, we proposed a model describing the relative position of the main and additional resonance peaks. The model predicts induced birefringence based on the frequency difference between the main and additional peaks. For experimental verification, we fabricated an optical ring resonator, measured the difference between the main and additional peaks and obtained the birefringence value. This value was –(3.42 ± 0.51)·10−7, consistent with values obtained in other studies.

Stability in self-injection locking of the DFB laser through a fiber optic resonator

Self-injection locking is an efficient technique to lock the frequency of laser at the resonant frequency of external cavity, which can be used for the all-optical frequency locking of the resonant optical gyroscope instead of the electric frequency locking. However, this technique is very sensitive to the system parameters and environmental disturbances. In this paper, we theoretically and experimentally analyze the dependences of injection ratio, intimal phase delay, operating temperature of distributed feedback (DFB) laser, and the environment temperature disturbance on the stability of self-injection locking. With the DFB laser self-injection locking to a high-Q fiber optic resonator (FOR), the frequency stability achieves less than 100 kHz in 30 min without active electrical feedback.

Surface Plasmon Plastic Optical Fiber Resonance with Multi-Layer as Chemical Sensor

A chemical optical fiber sensor based on surface plasmon resonance (SPR) was developed and implemented using multimode plastic optical fiber. The sensor is used to detect and measure the refractive index and concentration of various chemical materials (Urea, Ammonia, Formaldehyde and Sulfuric acid) as well as to evaluate the performance parameters such as sensitivity, signal to noise ratio, resolution and figure of merit. It was noticed that the value of the sensitivity of the optical fiber-based SPR sensor, with 60nm and 10 mm long, Aluminum(Al) and Gold (Au) metals film exposed sensing region, was 4.4 μm, while the SNR was 0.20, figure of merit was 20 and resolution 0.00045. In this work a multimode plastic optical fiber with a core diameter of 980 μm, fluorinated polymer cladding of 20 μm and a numerical aperture of 0.51 was used.

Arbitrarily high time bandwidth performance in a nonreciprocal optical resonator with broken time invariance

Most present-day resonant systems, throughout physics and engineering, are characterized by a strict time-reversal symmetry between the rates of energy coupled in and out of the system, which leads to a trade-off between how long a wave can be stored in the system and the system’s bandwidth. Any attempt to reduce the losses of the resonant system, and hence store a (mechanical, acoustic, electronic, optical, or of any other nature) wave for more time, will inevitably also reduce the bandwidth of the system. Until recently, this time-bandwidth limit has been considered fundamental, arising from basic Fourier reciprocity. In this work, using a simple macroscopic, fiber-optic resonator where the nonreciprocity is induced by breaking its time-invariance, we report, in full agreement with accompanying numerical simulations, a time-bandwidth product (TBP) exceeding the ‘fundamental’ limit of ordinary resonant systems by a factor of 30. We show that, although in practice experimental constraints limit our scheme, the TBP can be arbitrarily large, simply dictated by the finesse of the cavity. Our results open the path for designing resonant systems, ubiquitous in physics and engineering, that can simultaneously be broadband and possessing long storage times, thereby offering a potential for new functionalities in wave-matter interactions.

A mathematical model for scanning an arbitrary resonant contour by continuous wave three-frequency laser radiation

A mathematical model for scanning an arbitrary optical fiber resonance structure with an ultra-narrow spectral shape by a continuous wave three-frequency asymmetric by amplitude signal is proposed. It is shown that the three-frequency asymmetric scanning method has significant advantages over the methods of symmetric poly-harmonic scanning with suppressed carrier. In addition, the proposed method allowing study the spectral characteristics of ultra-narrow resonant circuits, since the method involves measuring beats at the difference frequencies of the initial three-frequency radiation, which can be of the order of several tens of megahertz.

Temperature effect on optical filter based on fiber-optic resonator using polarization and birefringence effects in the resonator loop

In this paper an analysis of optical filter based on fiber-optic ring resonator using polarization and birefringence effects in the resonator loop is presented. The temperature variations, which affect the refractive index and radius of the ring, would cause a change in the filter response. The simulation results show that the resonant wavelengths would shift toward longer wavelengths and output intensity changes with increasing temperature. It is shown that for every 10 deg C change in temperature, would cause the resonance wavelength to increase by 0.1 .

Swift-Hohenberg equation with third-order dispersion for optical fiber resonators

We investigate the dynamics of a ring cavity made of photonic crystal fiber and driven by a coherent beam working near to the resonant frequency of the cavity. By means of a multiple-scale reduction of the Lugiato-Lefever equation with high-order dispersion, we show that the dynamics of this optical device, when operating close to the critical point associated with bistability, is captured by a real order parameter equation in the form of a generalized Swift-Hohenberg equation. A Swift-Hohenberg equation has been derived for several areas of nonlinear science such as chemistry, biology, ecology, optics, and laser physics. However, the peculiarity of the obtained generalized Swift-Hohenberg equation for photonic crystal fiber resonators is that it possesses a third-order dispersion. Based on a weakly nonlinear analysis in the vicinity of the modulational instability threshold, we characterize the motion of dissipative structures by estimating their propagation speed. Finally, we numerically investigate the formation of moving temporal localized structures often called cavity solitons.

Variational approach to study soliton dynamics in a passive fiber loop resonator with coherently driven phase-modulated external field.

We report a detailed semianalytical treatment to investigate the dynamics of a single cavity soliton (CS) and two copropagating CSs separately in a Kerr mediated passive optical fiber resonator which is driven by a phase-modulated pump. The perturbation is dealt with by introducing Rayleigh's dissipation function in the framework of a variational principle that results in a set of coupled ordinary differential equations describing the evolution of individual soliton parameters. We further derive closed-form expressions for quick estimation of the temporal trajectory, drift velocity, and the phase shift accumulated by the CS due to the externally modulated pump. We also extend the variational approach to solve a two-soliton interaction problem in the absence as well as in the presence of the externally modulated field. In the absence of a phase-modulated field, the two copropagating solitons can attract, repulse, or propagate independently depending on their initial delay. The final state of interaction can be predicted through a second-order differential equation which is derived by the variational method. While in the presence of the phase-modulated field, the two-soliton interaction can result in annihilation, merging, breathing, or a two-soliton state depending on the detuning frequency and the pump power. Variational treatment analytically predicts these states and portrays the related dynamics that agrees with the full numerical simulation carried out by solving the normalized Lugiato-Lefever equation. The results obtained through this variational approach will enrich the understanding of complex pulse dynamics under a phase-modulated driving field in passive dissipative systems.

All-fiber MZI-Interleaver with self-feedback fiber resonator

In order to improve the transmission performance of all-fiber Mach-Zehnder interferometer (MZI), a novel all-fiber MZI interleaver is proposed and discussed in this paper. All-fiber interleaver consists of one 2×2 fiber coupler and one coupler with self-feedback fiber ring resonator. According to its structure, the output expression of the device is deduced by using optical fiber transmission theory and matrix theory, and numerical simulation analysis is performed. The results show that the device adopts the phase adjustment effect introduced by the self-feedback optical fiber resonator with reasonable parameters, and its 25 dB cutoff bandwidth is 46.7 GHz which accounts for 93.4% of the 50 GHz frequency interval. The output spectrum is similar to the square wave output. This device requires 2 fiber couplers, which is less than the number of couplers needed for the conventional all-fiber MZI-interleaver. When considering the existence of transmission loss, there is no difference in the amplitude of the two interference optical signals, which reduces the influence of transmission loss on the extinction characteristics of the filter. Compared with the conventional unbalanced MZI type interleaver with an optical fiber resonant ring, the structure is simple and compact, and has a certain anti-deviation ability. It also reduces the difficulty of making the device, which makes it play an important role in the future of dense wavelength division multiplexing systems.

Resonant enhancement of plasmonic nanostructured fiber optic sensors

Improving the sensing capabilities of miniaturized probes nanofabricated on the tip of optical fibers is crucial for a large number of sensing applications in remote and harsh environ-ments. While most research efforts are directed towards developing improved fabrications techniques or more sensitive structures, we show that the performance of these sensors can be significantly enhanced by designing an appropriate interrogation strategy. In our scheme, a nanostructured plasmonic fiber probe is included in an optical fiber resonator and interrogated with a single-mode laser. A wavelength shift of the plasmonic resonance generates a mismatch of the resonator optical impedance, which is monitored and actively compensated by an optoelectronic gain element. We characterize the technique using samples with different refractive index and compare its performance to a conventional sensing scheme. Our cavity-enhanced configuration leads to a 50-fold improvement of the probe’s refractive index resolution (corresponding to a detection limit of 10−5 RIU, the lowest reported so far for this type of sensors). The demonstrated measurement scheme can be devised with any fiber-optic sensor that responds with a resonance shift or with an attenuation of the transmitted/reflected intensity.

Elliptic-type soliton combs in optical ring microresonators

Soliton crystals are periodic patterns of multi-spot optical fields formed from either time or space entanglements of equally separated identical high-intensity pulses. These specific nonlinear optical structures have gained interest in recent years with the advent and progress in nonlinear optical fibers and fiber lasers, photonic crystals, wave-guided wave systems and most recently optical ring microresonator devices. In this work an extensive analysis of characteristic features of soliton crystals is carried out, with emphasis on their one-to-one correspondance with Elliptic solitons. In this purpose we examine their formation, their stability and their dynamics in ring-shaped nonlinear optical media within the framework of the Lugiato-Lefever equation. The stability analysis deals with internal modes of the system via a $2\times2$-matrix Lam\'e type eigenvalue problem, the spectrum of which is shown to possess a rich set of boundstates consisting of stable zero-fequency modes and unstable decaying as well as growing modes. Turning towards the dynamics of Elliptic solitons in ring-shaped fiber resonators with Kerr nonlinearity, first of all we propose a collective-coordinate approach, based on a Lagrangian formalism suitable for Elliptic-soliton solutions to the nonlinear Schr\'odinger equation with an arbitrary perturbation. Next we derive time evolutions of Elliptic-soliton parameters in the specific context of ring-shaped optical fiber resonators, where the optical field evolution is tought to be governed by the Lugiato-Lefever equation. By solving numerically the collective-coordinate equations an analysis of the amplitude, the position, the phase of internal oscillations, the phase velocity and the energy is carried out and reveals a complex dynamics of the Elliptic soliton in ring-shaped optical microresonators.

Liquid refractometric sensors based on optical fiber resonators

A robust, easy-to-fabricate, and sensitive liquid refractometric sensor utilizing optical fiber resonators (OFRs) obtained by simple stripping and cleaning of conventional optical fibers is presented. The sensing scheme is based on recording the spectral changes of the whispering gallery modes (WGMs) observed in the transmission spectrum of an OFR excited with a tunable laser coupled to the OFR through an independent tapered optical fiber. The demonstrated sensor device is tested and fully characterized with water solutions of ethanol and ethylene glycol (EG). Good agreements are obtained with theoretical predictions for both ethanol and EG cases when TE and TM polarized WGMs are considered. The limit of detection of the demonstrated sensor is determined to be between 2.7 and 4.7×10−5 refractive index unit (RIU) comparable to the state-of-the-art when precise temperature control of the sample chamber is missing.

Optical fiber group delay measurement based on laser beat frequency

AbstractA new method for optical fiber group delay measurement is proposed and experimentally demonstrated based on laser beat frequency. When the laser wavelength in the optical fiber resonator changes, the time delay through the optical fiber under test will change accordingly, leading to a change of round trip time in the optical fiber laser resonator. While the round trip time is the reciprocal of the minimum beat frequency, the group delay of the optical fiber under test which is placed in the fiber laser resonator can be easily obtained by measuring the beat frequency variation via the radio frequency spectrum analyzer. The optical fiber laser resonator utilized in experiments is composed of two reflectors: one is a sagnac loop composed of a coupler, the other is a composite structure composed of an optical circulator connected with a Fiber Fabry‐Perot Tunable Filter. The group delay of the single‐mode fiber and the dispersion compensating fiber are measured respectively in a relatively wide spectral range. Experimental results show that this method is feasible. Furthermore, this method is of very simple structure and low cost compared with other conventional methods.

Highly sensitive nano-aerosol detection based on the whispering-gallery-mode in cylindrical optical fiber resonators

ABSTRACTHighly sensitive detection of nanoscale aerosols, or nano-aerosols, is a difficult challenge. Here, we report a fiber optical technique that is capable of detecting trace-level nano-aerosols. Our method is based on monitoring the nano-aerosol-induced resonance shift due to the optical Whispering-Gallery-Mode (WGM) in a cylindrical optical fiber resonator. A nearly linear relationship between the WGM resonance shift and the aerosol coverage ratio of silica nanoparticles (40–50 nm dia.) on the fiber resonator was identified in the low coverage regime. Our experimental results imply sensitivity at the level of ∼2 nanoparticles per μm2 deposited on the fiber resonator, which corresponds to pg-level sensitivity in the total aerosol mass within the effective detection area. The response of this fiber optical sensor is further confirmed by using silica nanoparticles deposited on the fiber surface via electrostatic self-assembly. The fiber optical technique for nanoparticle detection may ultimately lead t...