Optical Fiber Ring Resonator Research Articles

A quantum-chaotic encoding system using an erbium-doped fiber amplifier in a fiber ring resonator

This paper firstly presents a new concept of quantum-chaotic encoding of light traveling in a fiber optic ring resonator. The pumping input power can be controlled to generate the chaotic behavior of the circulated light within the fiber ring resonator. The Kerr nonlinear type of light circulating in a fiber optic ring resonator is induced and the superposition i.e. four-wave mixing of the propagating waves at resonance occurred. The output signals can be used to generate two different codes, of which one is the quantum bits i.e. code, the other is the chaotic signal i.e. code. The proposed system has shown the potential of using for communication security, where the double security via quantum-chaotic can be performed.

Entangled photon states generation and regeneration using a nonlinear fiber ring resonator

We propose a simple system of the entangled photon states generation and regeneration using a standard diode laser, a Mach Zehnder Interferometer (MZI) and a fiber optic ring resonator (FORR). Light from the diode laser is launched into an MZI and circulated in the FOOR, without any optical pumping components included in the system. The nonlinear light pulses are generated by a Kerr nonlinear effects type, while the resonance peaks are formed by the four-wave mixing of light pulses in the FORR. The entangled photons can be performed by using the polarization control device, and then detected by the avalanche photo-detectors, where the entangled photon visibility is plotted and seen. Similarly, the entangled photon states can be easily formed by using the appropriated coupling ratios into a fiber coupler, then into a ring resonator, i.e. without an MZI. The use of the entangled photons generation based on a fiber optic scheme for quantum teleportation, quantum key distribution via optical wireless link, and the system of the entangled photon states recovery by using a fiber ring resonator incorporating an erbium-doped fiber (EDF) have been investigated and discussed. The feasibility of dense coding using multi-entangled photons generation based on the fiber optic scheme and the effect of the entangled state walk-off along the optical fiber are also discussed, respectively.

An investigation of the entangled photon walk-off compensation generated by a fiber ring resonator

We firstly present an experimental investigation of the entangled photon states’ recovery using a fiber optic ring resonator incorporating an erbium-doped fiber amplifier (EDFA). The weak light entangled photons can be recovered in both amplitude and states after the optical pumping and polarization control parts are used in the system. A new experimental result of the investigation of thermal effects on the entangled states’ walk-off and compensations has shown that the entangled photon walk-off compensation is achieved by using a pair of polarization control devices. The relationship between thermal effects and the entangled states’ phase shift is investigated and discussed. The walk-off compensation due to temperature changes from 30 to 80 °C is achieved. This shows that the changes in phase of the entangled photons can be negligible when the compensation is employed.

Four entangled photons generation using weak light and an all fiber optic scheme for multi-entangled photons generation

This paper proposes a simple scheme of four entangled photons generation using a pulse of weak light input into a Mach–Zehnder interferometer (MZI) incorporating a fiber optic ring resonator (FORR) without any optical pumping components included in the system. After a pair of entangled photon has been generated by a four-wave mixing of weak light pulse in the FORR [P.P. Yupapin, S. Suchat, Entangled photon generation using fiber optic Mach–Zehnder interferometer incorporating the nonlinear effect in a fiber ring resonator, Journal of Nanophotonics (JNP) 1 (2007) 013504], four and eight entangled photons can be performed. In application, the multi-entangled states can be formed using the appropriated coupling ratios into a fiber coupler. The effect of the entangled state walk-off along the optical fiber is discussed.

Analysis of a fiber ring resonator as a multi-path light-wave circuit in white-light fiber-optic interferometric sensors

According to the phase shift response of a ring resonator, the role of a fiber-optic ring resonator as a multi-path light-wave circuit in white-light fiber-optic interferometric sensors is analyzed. Formulas related to the maximum intensity of the interference fringes and the system parameters are derived by exact mathematic deduction. The main factors affecting the multiplexing capability of the sensor array are discussed. The analysis method not only gives an explicit explanation for the enhancement of multiplexing capability but also can be applied to other structural white-light sensor systems, in which the ring resonator is used as a multi-path light-wave circuit.

Nonlinearity penalties and benefits of light traveling in a fiber optic ring resonator

The nonlinearity properties of light traveling in a fiber optic ring resonator (FORR) are presented. The nonlinearity penalties suffering from Kerr effects and four-wave mixing nonlinear types including bistability, chaos and bifurcation are investigated. The advantages of the nonlinearity penalties including photon correlation, optical switching and information security using chaotic signals are also discussed. The obtained results have shown that the parameters of FORR can be changed, and thus the penalties of the nonlinear effects have shown the potential of using for some applications.

Proposal for nonlinear refractive index measurement using spectral ratio in modulated OFRR dynamics

A novel method for measuring the nonlinear refractive index of an optical fiber using a spectral ratio between the modulation frequency and a harmonic component in a modulated optical fiber ring resonator (OFRR) is proposed. The spectral ratio between the modulation frequency and the 2nd-harmonics generated by phase-modulation through the OFRR is increased with increasing the input light power and has peaks above 5W input power, however, the peaks was shifted to the lower input power below 1W by averaging taken into account of the phase distribution. A experimental setup consisted of an OFRR system and an Ar-laser as a pump light source was used to determine the nonlinear refractive index of an optical fiber. In the experimental results, the peaks of the spectral ratio as a function of the input power was found out at 0.8W and 0.45W of the input power corresponding to the input source line at 488.0nm and 514.5nm, respectively. The profile was similar to that obtained by the simulation and the nonlinear refractive index of a optical fiber was determined as 1.0×10−22m2/V2 by a relationship between the input power giving the peak and the nonlinear refractive index.

Chaotic signal generation and cancellation using a micro ring resonator incorporating an optical add/drop multiplexer

We propose a new design of a chaotic signal generation and cancellation system using an all fiber optic scheme. A system consists of a standard diode laser, a fiber optic micro ring resonator, and an optical add/drop multiplexer. When light from the diode laser is input into the fiber ring resonator, the chaotic signal can be generated by using the selected fiber ring resonator parameters and the diode laser input power. The required signal is obtained in the transmission link via the add/drop device by a specific user at the drop port. Simulation results obtained have shown the potential of application, especially, when the practical ring radius is 10 μm with the optical input power is in the range of the communication standard diode laser, for instance, when the coupling coefficients of the add/drop device are κ 1 = 0.01 and κ 2 = 0.01–0.9. When the add port of the add/drop device is employed, such a system can also be utilized for the multi user applications.

An experimental investigation of the optical switching characteristics using an optical Sagnac interferometer incorporating one and two ring resonators

We present the use of a fiber optic Sagnac interferometer incorporating one and two fiber optic ring resonators to characterize experimentally the optical switching behaviors. These prototypes were formed by the Sagnac interferometer and serially connected to the ring resonators. The input optical signal was launched via one end of the interferometer, where the polarization control was employed to obtain the maximum optical transmission power. Results obtained have shown that the increasing in switching time (i.e. narrower spectral width) and power can be achieved.

COUPLER-LOSS AND COUPLING-COEFFICIENT DEPENDENCE OF BISTABILITY AND INSTABILITY IN A FIBER RING RESONATOR: NONLINEAR BEHAVIORS

In this paper we demonstrate the dynamic simulation of light traveling in a nonlinear fiber optic ring resonator (FORR) with a single coupler. The mathematical relations describing the nonlinear characteristics of the FORR are derived from light transmission theory in linear optical systems. Optical nonlinear phenomena such as bifurcation and chaos are investigated for optical bistability and the Ikeda instability. It is found that for the Ikeda instability of light inside a FORR, the ring-cavity lifetime is much longer than the Kerr-effect response time of the fiber ring. Transmission curves of bistability and instability are shown as a function of the coupler insertion losses (γ) and the coupling coefficients (κ).

LOW COHERENCE PULSED DOPPLER LIDAR WITH AMPLIFIED REFERENCE BEAM STORAGE

In this paper, we have successfully developed a new low coherence pulsed Doppler lidar concept for wind speed measurements, in which a pulsed laser is used as the source for measurement and reference beam. A fraction of the transmitted pulse is stored in a fiber optic ring resonator with a path length longer than the pulse. The output of the resonator is a pulse train that is used as the reference beam and can be mixed with the Doppler shifted measurement signal. Because this reference has traveled a distance equivalent to the measurement beam’s path length, low coherence sources can be used. Inserting an erbium-doped fiber amplifier into the resonator ensures that the stored pulses do not decay in amplitude. Careful control of gain and amplified spontaneous emission is required to prevent laser oscillation while maintaining sufficient gain for the signal. Experiments prove that 16 reference pulses of sufficient amplitude and stability can be generated. Computer simulations suggest that 70 pulses should be achievable, which would be equivalent to a Doppler lidar measurement range of 2,550 m.

Entangled photon generation using a fiber optic Mach-Zehnder interferometer incorporating the nonlinear effect in a fiber ring resonator

A new system for entangled photon-pair generation using an all-fiber optic scheme consists of a fiber optic Mach-Zehnder interferometer (MZI) incorporating a fiber optic ring resonator. The Kerr nonlinearity effect in the fiber ring resonator is exploited for the generation of two independent squeezed beams. The advantage of such a system is that it requires a simple arrangement without any optical pumping parts or bulky optical components. Polarized light pulse trains are launched randomly into a MZI, and one part of the light is delayed in the longer path. The output pulses from both arms of the MZI enter a fiber optic ring resonator. A polarization controller controls the polarization states of the light pulses while they circulate in the ring resonator. The superposition of the nonlinear light pulses in a fiber optic ring resonator randomly occur. These forms are seen on an avalanche photodetector. The results are in good agreement with previous work.

Amplified reference pulse storage for low-coherence pulsed Doppler lidar

We present a lidar concept for wind-speed measurements, in which a pulsed laser is used as the source for measurement and reference beams. A fraction of the transmitted pulse is stored in a fiber-optic ring resonator with a path length longer than the pulse. The output of the resonator is a pulse train that is used as the reference beam and can be mixed with the Doppler-shifted measurement signal. Because this reference has traveled a distance equivalent to the measurement beam's path length, low-coherence sources can be used. Inserting an erbium-doped fiber amplifier into the resonator ensures that the stored pulses do not decay in amplitude. Experiments prove that 16 reference pulses of sufficiently constant amplitude and stability can be generated. This would correspond to a measurement range of 240 m in free air over which the returned signal is sampled at equal intervals. Velocity measurements of a hard target have been carried out in the range of 1-10 m/s. The Doppler-measured velocities agree with tachometer reference measurements within +/-0.09 m/s.

Decryption characteristics in message modulation type chaos secure communication system using optical fiber ring resonators

Message modulation type chaos secure communication system using optical fiber ring resonators is analyzed numerically. It is found that the decryption characteristics degrades monotonically as the differences in parameters which are not included in the linear phase term becomes large, while they degrade periodically with a period of 2π as the differences in parameters included in the linear phase term increase. When a noise is added in the input light, the error dispersion in the message demodulation is determined by the noise level in the small parameter difference region, while the parameter differences it dominates in the large parameter difference region. Best decryption characteristics are always obtained at the minimum input power for the chaos generation, i.e., at the lowest Lyapnov exponent in chaos state in the message modulation type chaos secure communication system using optical fiber ring resonators.

Periodic chaos synchronization in slave subsystems using optical fiber ring resonators

Synchronization characteristics of chaos generated in optical fiber ring resonators are analyzed numerically for slave subsystems. It is found that highly synchronized chaos appears periodically with the period of one wavelength in a difference in resonator length between the two slave subsystems. It is remarkable that the difference in system parameters included in the phase results in the periodic synchronization whose period corresponds to 2π phase shift. The correlation coefficient degrades gradually with an increase in a much wide range in the phase parameter difference. In addition, synchronization characteristics become worse monotonically as the difference in other system parameters not included in phase increase.

Multiplexing of fiber-optic white light interferometric sensors using a ring resonator

A single-mode fiber-optic ring resonator is used as a multipath reference for multiplexing white light interferometric sensors. The theory of applying the resonator for multiplexing Michelson-type interferometer sensor is presented. The capacity of the technique in terms of maximum sensor number is evaluated for both a linear array and a M x N sensor matrix. Experimental results for a three-sensor linear array and 2 x 1 sensor matrix are also presented.

Coherence effect on nonlinear dynamics in fiber-optic ring resonator

Dependence of nonlinear dynamics generated in an optical fiber ring resonator on source coherence is investigated numerically. Chaotic and periodic behaviors are found to have reduced moduli with maintained patterns which become time independent as source spectrum width increases. Output bifurcation characteristics are independent of source coherence but are dependent on loss and other resonator parameters. Coherence length which is longer than resonator length is required for chaotic output. The critical spectrum width at which output becomes time independent is inversely proportional to fiber ring resonator length. In addition, critical spectrum width decreases with increased fiber ring resonator loss.

Reference-beam storage for long-range low-coherence pulsed Doppler lidar

We present a laser Doppler velocimeter that stores and delays the reference beam to preserve coherence with a long-path-length measurement beam. Our storage and delay technique relaxes the strict coherence requirements associated with lidar laser sources, permitting the use of low-coherence lasers. This technique potentially could reduce the cost and size of lidar systems for commercial applications. Experiments that use fiber-optic ring resonators to store the reference beams and generate reference pulse trains validated the concept. We obtained results at several simulated distances by beating each usable reference pulse with a delayed Doppler-shifted measurement beam reflected off a rotating mirror.

Equations of motion from chaotic data: A driven optical fiber ring resonator

We apply a recently proposed method for the reconstruction of equations of motion from a time series to experimental chaotic optical data and find the theoretically expected Ikeda model. In contrast to phase space reconstruction methods, it is based on nonlinear regression and maximal correlation, and the resulting model can be investigated further. We demonstrate the retrieval of physical parameters by calculating the experimentally not accessible phase evolution of a non-stationary data set.

Effects of resonator's optical path fluctuation on the characteristics of a fibre-optic ring resonator

The effect of a resonator's optical path fluctuation (ROPF) on a fibre-optic ring resonator is described. It makes the transmission characteristics degrade and the effective fineness decrease. It is similar to the effect of light-source temporal coherence, but different from that of the continuous resonator's optical path alteration.