Direct measurement of pulse distortion near the zero-dispersion wavelength in an optical fiber by frequency-resolved optical gating

The technique of frequency-resolved optical gating is used to characterize the intensity and the phase of picosecond pulses after propagation through 700 m of fiber at close to the zero-dispersion wavelength. Using the frequency-resolved optical gating technique, we directly measure the severe temporal distortion resulting from the interplay between self-phase modulation and higher-order dispersion in this regime. The measured intensity and phase of the pulses after propagation are found to be in good agreement with the predictions of numerical simulations with the nonlinear Schr?dinger equation.     

Direct measurement of superluminal group velocity and signal velocity in an optical fiber

We present an easy way of observing superluminal group velocities using a birefringent optical fiber and other standard devices. In the theoretical analysis, we show that the optical properties of the setup can be described using the notion of "weak value." The experiment shows that the group velocity can indeed exceed c in the fiber; and we report the first direct observation of the so-called "signal velocity," the speed at which information propagates and that cannot exceed c.     

Direct picture transmission in a single optical fiber with holographic filters

A composite holographic filter of many superimposed holograms succeeds in restoring a picture which is invariably in a scrambled state because of direct transmission through a single step-index multimode optical fiber.     

Transmission of an optical frequency through a 3 km long optical fiber

A 3 km long optical fiber is used to connect two laboratories in Paris. We present the metrological properties of this optical link to transfer an optical frequency standard at 778 nm and we show that the frequency shift introduced by the fiber is only of few Hz. Received: 23 October 1997 / Accepted: 18 November 1997     

Bragg modulational instability induced by a dynamic grating in an optical fiber

By means of a dynamic Bragg grating obtained through cross-phase modulation with a beating wave in a highly birefringent fiber, we perform a detailed experimental study of Bragg modulational instability.     

High-efficiency generation of a supercontinuum in an optical fiber

The results of experimental studies of high-efficiency generation of a supercontinuum in different types of single-mode optical fibers by pulses with a width of ～20 ps and with a wavelength widely tunable within the regions of normal and anomalous dispersion of the fibers are reported. A high efficiency of transformation of initially monochromatic radiation into a wide-spectrum supercontinuum with intense wings (in the range of 1000–2100 nm at a transformation efficiency of 95%) is demonstrated.     

Near-field optical polarimetry of plasmonic nanowires

Local polarization properties of a gold subwavelength grating with plasmon-induced linear dichroism are studied by scanning near-field optical dynamic polarimetry. Periodic modulation of linear dichroism with the period corresponding to the period of the grating and the contrast of 0.3 is found at the distance of λ/20 from the sample.     

Direct determination of the Boltzmann constant by an optical method

We have recorded the Doppler profile of a well-isolated rovibrational line in the nu(2) band of (14)NH(3). Ammonia gas was placed in an absorption cell thermalized by a water-ice bath. By extrapolating to zero pressure, we have deduced the Doppler width which gives a first measurement of the Boltzmann constant k(B) by laser spectroscopy. A relative uncertainty of 2 x 10(-4) has been obtained. The present determination should be significantly improved in the near future and contribute to a new definition of the kelvin.     

Reconfigurable time-domain spectral shaping of an optical pulse stretched by a fiber Bragg grating

We demonstrate a method for spectrally shaping optical pulses that is readily reconfigurable and can produce variable filter functions. This practical technique relies on a compact and robust 3.86-m-long linearly chirped fiber Bragg grating that chromatically disperses the pulse to ~30 ns. We then shape the pulse envelope, and thus the pulse spectrum, with a programmable arbitrary waveform generator and an amplitude modulator to obtain several filter functions.     

Modulation instability in an optical fiber induced by cross-phase modulation

Radiophysics Research Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 1, pp. 84–88, January, 1991.     

Laser amplification in an optical fiber by evanescent field coupling

A laser signal propagating in an optical fiber is amplified by the evanescent field interacting with the excited Rhodamine 6 G solution surrounding the fiber. A small signal gain of 430 at 600 nm has been measured in a long fiber with a 2 cm long fiber optic amplifier.     

Development of an optical fiber hydrophone with fiber Bragg grating

A new type of optical fiber hydrophone is constructed with a fiber Bragg grating (FBG) based on the intensity modulation of laser light in an FBG under the influence of sound pressure. The FBG hydrophone shows linearity, with dynamic range about 70 dB. It can measure amplitude and phase of an acoustic field in real time, and operates in a wide range of acoustic frequency, at least from 1 kHz to 3 MHz. No signal distortion is observed in the detected signal. Because of the simplicity in its operating principle and geometry, an FBG hydrophone is expected to be an acoustic sensor of high practicality compared to a conventional optical fiber hydrophone.     

Soliton formation from a gaussian pulse in an optical fiber

Propagation of a frequency-modulated Gaussian pulse along an optical fiber with a gradient refractive index is studied. It is shown that, after propagating a certain distance, the pulse undergoes compression. If, at the point of maximum compression, the pulse intensity is exactly equal to the threshold intensity, then either a bright or dark vortex soliton can form.     

带光纤环的分布式光纤拉曼温度系统

 为了抑制分布式光纤拉曼温度系统的温漂和瑞利散射光窜扰反斯托克斯散射光,在传感光纤前端盲区后放置光纤取样环,用瑞利散射光解调反斯托克斯散射光及用光纤取样环的温度计算光纤线上其它点的温度,提高了系统的测温精度和稳定性。采用功率100 mW,波长1.55 μm,脉宽10 ns脉冲激光器和15 dB前置光纤放大器,100M14bitA/D转换卡及DSP作数字平均构建光纤拉曼温度系统的实验,实现了测温误差在±0.03 ℃内。     

Radio emission of an optical soliton propagating in a ring fiber

Considered are emission processes occuring in the course of propagation of an optical soliton along a ring fiber. The spatial and temporal characteristics of radiation are calculated. It is demonstrated that conditions are possible in which radiation becomes observable.     

Dynamics for two cavity QED systems coupled by an optical fiber

We discuss the one-excitation dynamics of two atomic qubits, trapped in separate cavities coupled through a short optical fiber. Our investigation shows that a wide variety of time-evolution behaviors can be realized by modulating the atom-cavity detuning δ, the atom-cavity coupling strength g and the cavity-fiber hopping strength v.