Rhodamine 6G-doped polymer optical fiber amplifiers

Rhodamine 6G-doped step-index polymer optical fiber is fabricated. The characteristics of the amplification of rhodamine 6G-doped step-index polymer optical fiber amplifier have been studied. The high-gain optical amplification with a tunable wavelength range from 585 to 613 nm is obtained in a step-index polymer optical fiber doped with rhodamine 6G at 10-ppm level, which can be used for broadband amplifiers and tunable lasers.     

Incoherent broadband optical pulse generation using an optical gate

In two-dimensional(2D)time-spreading/wavelength-hopping optical code division multiple access (OCDMA)systems,employing less coherent broadband optical pulse sources allows lower electrical oper- ating rate and better system performance.An optical gate based scheme for generating weakly coherent (approximately incoherent)broadband optical pulses was proposed and experimentally demonstrated.In this scheme,the terahertz optical asymmetric demultiplexer,together with a coherent narrowband control pulse source,turns an incoherent broadband continuous-wave(CW)light source into the required pulse source.     

Piezooptical optical bistability

A glass fiber piezooptical optical bistability device is reported.Basing on pho-toelastic and strain effects of single-mode fiber,we have realized piezooptical modulation andperformed experiments of optical bistability.     

An optical method for wavelength fine-selection in optical spectrum analysers

This letter describes a novel optical method for wavelength fine-selection in the optical spectrum analysers (OSAs) for dense wavelength division multiplexing (DWDM) applications. The proposed new method employs a 'refractive optical lever' system consisting of a rotating optical wedge prism. A new OSA system based on Littman-type monochromator is proposed and the wavelength selection accuracy and resolution of OSA that has included such an optical lever system have been improved by a factor of 20 to 100 depending on the wedge angle and offset orientation angle of the optical wedge prism. This proposed 'refractive optical lever' may also simplify the rotation mechanism of the mirror in the commercially available OSAs.     

Linear optical properties of γ-modification of bismuth borate BiB3O6

The refractive index dispersion of the ??-BiB₃O₆ crystal in the wavelength range 0.43?C0.81 ??m has been measured. It has been shown that the principal refractive indices n ₁, n ₂, and n ₃ are on average higher than those of ??-BiB₃O₆, but are slightly lower than those of ??-BiB₃O₆. The temperature dependences of the rotation angle ??(T) of the optical indicatrix and birefringence ??n ₂(T) = (n ₁ ? n ₃)(T) have been studied in the temperature range 100?C963 K. It has been shown that the ??-BiB₃O₆ crystal is stable in this temperature region.     

Separation and insertion of optical bit-serial label in optical packet switching

The bipolar phase-shift-keying (BPSK) optical orthogonal codes (OOCs) are inserted into the optical packet format of bit-serial label. The ultra-fast separation of the label and payload is performed through the auto-correlation pulses indicating the time position at which the optical switch changes the state. The insertion of the new label can also be realized by detecting the auto-correlation pulse at the line rate. Especially, the scheme can be adapted to the asynchronous separation and insertion and realize the variable-length packet switching. The results of simulation verify the feasibility of the scheme.     

Beam-shaping microstructure optical fiber

Microstructure optical fiber with uniform intensity distribution of the fundamental mode is proposed. The design guide line and characteristics of this kind fiber are demonstrated. The relationship between refractive index profile and structure parameters is investigated. The mechanism of forming uniform fundamental mode in these fibers is analyzed.     

Controllable optical delay line using a Brillouin optical fiber ring laser

A controllable optical delay line using a Brillouin optical fiber ring laser is demonstrated and a large time delay is obtained by cascading two optical fiber segments. In experiment, a single-mode Brillouin optical fiber ring laser is used to provide Stokes wave as probe wave. We achieve a maximum tunable time delay of 61 ns using two cascading optical fiber segments, about 1.5 times of the input probe pulse width of 40 ns. In the meantime, a considerable pulse broadening is observed, which agrees well with the theoretical prediction based on linear theory.     

Picosecond optical switching of a 1.5 μm active birefringent optical fiber loop filter using 1.3 μm control optical pulses and a 1.3 μm semiconductor optical amplifier

Less than 100ps, polarization-independent switching operation of an active birefringent optical fiber loop filter using 1.3 μm control optical pulses as well as a 1.3 μm semiconductor optical amplifier (SOA) has been demonstrated. In the proposed SOA-based active birefringent filter operating at 1.55 μm wavelength, 1.3 μm SOA is employed to control the polarization-mode dispersion in the loop part. By injecting 1.3 μm ps gain-switched optical control pulses into the SOA, 1.5 μm input signals can be switched from the transmission port to the reflection port with less than 100 ps rise time.     

Novel MEMS variable optical attenuator

A novel MEMS variable optical attenuator (VOA), which has completely different attenuation mechanism from those in literatures, is proposed and demonstrated in this paper. The basic operation principle is that the optical power coupled between two initially aligned single-mode fibers will be continuously attenuated while the end of one of the fibers is deflected from the initial position. A micromachined solenoid type inductor with a U-shaped permalloy magnetic core is used to attract the deflectable fiber that has a permalloy coat on its end. To fabricate the multi-layer three-dimensional inductive component, a new UV-LIGA process for thick photoresists is developed, combining advantages of both SU-8 and AZ-4000 series photoresists. The inductive component is approximately 1.7 mm×1.3 mm×50μm in size and has a low resistance value (- 2.1Ω). The whole size of the VOA before packaging is 30 mmx2 mmx0.6 mm. The first prototype shows less then 3-dB insertion loss at 0-dB attenuation and nearly 40-dB att     

Nonadiabatic nondegenerate excitation by optical near-field and its application to optical pulse-shape measurement

Using DCM dye grains and light of different wavelengths generated by two CW laser diodes that oscillate in the near-infrared wavelength region, visible light emission from dye grains due to near-infrared excitation based on a nonadiabatic, nondegenerate excitation process was observed for the first time. Unlike sum-frequency generation with nonlinear polarization, the difference in polarization angles of the two beams did not affect the emitted light intensity. Optical sampling based on this nonadiabatic, nondegenerate excitation principle was demonstrated for the first time. The optical pulse shape in the wavelength band of λ=1250–1350 nm, which is close to the wavelength range used for optical fiber communications, was measured with a temporal resolution of 0.8–1.1 ps.     

Electronic structure, optical properties and lattice dynamics of MgSO3·6H2O

The electronic band structure, optical properties and lattice vibrations of MgSO(3)·6H(2)O were studied within density functional theory and compared to the experimental optical data and polarized Raman spectra. Due to the 'molecular' nature of the MgSO(3)·6H(2)O crystal all Γ-point phonon modes could be separated into groups belonging to specific structural blocks: Mg(H(2)O)(6) octahedra, SO(3) units and H(2)O molecules. All Raman lines in the experimental spectra are assigned to definite vibrations of the structure and reasonable agreement is found between theoretical and experimental mode frequencies. The temperature-dependent Raman spectra reveal at 60 °C a sharp transition from MgSO(3)·6H(2)O to anhydrous amorphous MgSO(3) without the noticeable presence of intermediate lower hydrates, such as MgSO(3)·3H(2)O.     

Quartz optical filter for wavelength selection of frequency-doubled laser based on optical rotatory dispersion effect

Based on the optical rotatory dispersion effect,an optical filter for selecting the second harmonic of a frequency-doubled laser is constructed from quartz in combination with polarizers.The operating principle is analyzed by matrix formulation,and the result indicates that the second harmonic of a frequency-doubled laser will be obtained when the rotation angle has a difference of(2n 1)π/2 (n=0,1,2,3,...)between the two polarizations of the second-harmonic laser and the fundamental laser.The spectrum of the output laser is taken by the AQ-6315A spectrometer,and the experimental results are in good agreement with the theoretical results.     

Mode analysis of axially-asymmetric optical resonators

The characteristics of an axially-asymmetric optical resonator(AAOR)areanalysed by using the variable reference plane method.The positions of the beam waist andthe plane wavefront are obtained.The variation of the beam size ellipse and wavefront curva-ture ellipse are also discussed.     

Fabrication of 1×2 asymmetric plastic optical fiber coupler for portable optical access-card system

We proposed a simple low-cost acrylic and metal-based Y-branch plastic optical fiber (POF) splitter which utilizes a low cost optical polymer glue NOA63 as the main waveguiding medium at the waveguide taper region. The device is composed of three sections: an input POF waveguide, a middle waveguide taper region and output POF waveguides. A desktop high speed CNC engraver is utilized to produce the mold inserts used for the optical devices. Short POF fibers are inserted into the engraved slots at the input and output ports. UV curable optical polymer glue NOA63 is injected into the waveguide taper region and cured. The assembling is completed when the top plate is positioned to enclose the device structure and connecting screws are secured. Both POF splitters have an average insertion loss of 7.8 dB, coupling ratio of 55: 45 and 57: 43 for the acrylic and metal-based splitters respectively. The devices have excess loss of 4.82 and 4.73 dB for the acrylic and metal-based splitters respectively.     

The study of third harmonic demodulation in phase modulation optical heterodyne technique using optical resonator

With the technique of phase modulation optical heterodyne(PMOH), we detected the beat-frequency signal of the reflected wave from a F-P cavity. The frequency of the beat signal was three times of that of the modulation electric field, when the 3rd harmonic of the modulation electric field was used as the phase reference signal. The line shapes of the signal match those of the theoretical calculations, and the dispersion signal has good frequency-discrimination characteristic.     

Multi-component optical azimuthons of four-wave mixing

We report the multi-component optical azimuthons of four-wave mixing(FWM) composed of several modulated vortex beams, the so-called azimuthons, in V-type three-level and two-level atomic systems. We analyze the formation mechanisms of the FWM azimuthons theoretically and experimentally. In addition, we illustrate the interactions between the co-propagating azimuthon components. Finally, we also compare the stabilities of azimuthons in V-type three-level and two-level atomic systems.     

High-energy optical Schrödinger solitons

The conditions for the existence of a Lax pair were determined and exact analytic solutions to the nonlinear evolution equations of the Schrödinger type with complex and nonuniform potentials were found. In particular, these solutions provide a basis for the soliton management concept in applied problems and solve the problems of optimal energy accumulation by a Schrödinger soliton in an active medium and soliton amplification in optical fiber communication lines and soliton lasers.     

Spatial Fourier-decomposition optical fluorescence tomography-theoretical investigation

A new three-dimensional （3D） optical fluorescent tomographic imaging scheme is proposed with structured illumination and spatial Fourier-domain decomposition methods for the first time. In this spatial Fourierdecomposition optical fluorescence tomography （SF-OFT）, the intensity of focused excitation light from an objective lens is modulated to be a cosine function along the optical axis of the system. For a given position in a two-dimensional （2D） raster scanning process, the spatial frequency of the cosine function along the optical axis sweeps in a proper range while a series of fluorescence intensity are detected accordingly. By making an inverse discrete cosine transformation of these recorded intensity profiles, the distribution of fluorescent markers along the optical axis of a focused laser beam is obtained. A 3D optical fluorescent tomography can be achieved with this proposed SF-OFT technique with a simple 2D raster scanning process.     

General optical scintillation in turbulent atmosphere

A general expression of the scintillation index is proposed for optical wave propagating in turbulent at- mosphere under arbitrary fluctuation conditions.The expression depends on extreme behaviors of the scintillation indices under both weak and strong fluctuations.The maximum scintillation index in the onset region and the corresponding Rytov index can be evaluated from the general expression.Plane and spherical waves in the cases of zero and non-zero turbulence inner scale are given as examples for illustra- tion of the general behaviors of scintillation indices.