Hole-assisted lightguide fibers with small negative dispersion and low dispersion slope.

A nonzero dispersion shifted fiber design based on hole-assisted lightguide fiber is presented. The proposed fiber has low dispersion slope around -0.01 ps/nm(2)-km and small negative dispersion values over the wavelength range from 1530 to 1620 nm.

Low-loss air-core polarization maintaining terahertz fiber.

We propose a low-loss air-core polarization maintaining polymer fiber for terahertz (THz) wave guiding. The periodic arrangement of square holes with round corners in the cladding offers a bandgap effect for mode guiding. Numerical simulations show that the bandgap effect repels the modal power from the absorbent background polymers, resulting in a significant suppression of absorption loss of the polymers by a factor of more than 25.

Analytical method for band structure calculation of photonic crystal fibers filled with liquid crystal.

An analytical method for band structure calculations of photonic crystal fibers with liquid crystal infiltrations is presented. The scalar eigenvalue equation is extended to treat both isotropic and anisotropic materials by introducing a coefficient to describe the index contrast between the extraordinary and ordinary refractive index of the liquid crystal. The simple model provides a fast insight into bandgap formation in photonic crystal fibers filled with anisotropic material such as liquid crystal, which would be useful to aid the design based on such fibers.

Stress distribution and induced birefringence analysis for pressure vector sensing based on single mode fibers.

We propose a theoretical approach to analyze the pressure stress distribution in single mode fibers (SMFs) and achieve the analytical expression of stress function, from which we obtain the stress components with their patterns in the core and compute their induced birefringence. Then we perform a pressure vector sensing based on approximately 2 km SMF. Using Mueller matrix method we measure the birefringence vectors which are employed to compute the pressure magnitudes and their orientation.

Long path-length axial absorption detection in photonic crystal fiber.

In this paper, we present a long path-length axial absorption detection method in photonic crystal fibers (PCFs). A PCF, also called a holey fiber or microstructured fiber, is an optical fiber which consists of a periodic array of very tiny and closely spaced air holes on the scale of 1 microm running through the whole length of the fiber. Here, a PCF with porous microstructures was used as a sample container for absorption detection.

Experimental analysis of spectral characteristics of antiresonant guiding photonic crystal fibers.

Both numerical and experimental analyses are carried out to investigate the spectral characteristics of antiresonant guiding photonic crystal fibers. The transmission minima were observed at the wavelengths where LP(ml) (m View Article and Find Full Text PDF

Nonlinear soliton propagation by use of the split-step reconstruction technique.

A split-step reconstruction technique is proposed to solve a nonlinear wave equation. A nonlinear wave equation can be segmented into a set of linear equations that can be solved in the time domain by use of the split-step reconstruction technique. With this technique, one can avoid the propagation errors that occur as a result of nonlinear wave equation splitting.

Photonic ultrawideband monocycle pulse generation using a single electro-optic modulator.

A compact approach to photonic-assisted ultrawideband (UWB) monocycle pulse generation is proposed and experimentally demonstrated based on the wavelength dependence of the half-wave voltage of a Mach-Zehnder modulator (MZM). By employing a single MZM with dual-wavelength injection at around 1310 and 1550 nm, a pair of polarity-reversed monocycle pulses with the full width at half-maximum of about 80 ps and the fractional bandwidth of greater than 160% can be generated. The experiment results agree well with the theoretical prediction.

Ultra-wideband pulse generation with flexible pulse shape and polarity control using a Sagnac-interferometer-based intensity modulator.

We propose a novel scheme to generate ultra-wideband (UWB) pulse by employing a Sagnac interferometer comprising a phase modulator. This structure performs a dual-input and dual-output intensity modulator (IM), ultimately resulting in the flexibility to select the shape and the polarity of the generated UWB pulse. The experiment results show a good agreement with the theoretical investigation in terms of both pulse profile and spectrum, which conforms to the definition of UWB signals by the U.

Fabrication of all-solid photonic bandgap fiber coupler.

We report the fabrication of a tunable all-solid photonic bandgap fiber coupler based on the side-polishing technique. This device is believed to be the first demonstration of a photonic bandgap fiber coupler to eliminate the contamination of the open air holes. By adjusting the length of the interaction section, the tunable coupling ratio as much as 92.

Dispersion effect and compensation in optical-carrier-suppressed modulation transport systems.

We develop new expressions for power fading and average power fading that are induced by first-order polarization mode dispersion, polarization-dependent chromatic dispersion, chromatic dispersion, and chirp under both (i) carrier suppressed modulation and (ii) odd-order optical sideband and carrier suppression. Experimental results show the effectiveness of the theoretical analysis. Further, based on the expressions, we propose a technique for optically compensating the polarization mode dispersion-induced power fading in carrier suppressed modulation.

Spectrally resolved reflectometric measurement of polarization mode dispersion in an optical fiber link with polarization-dependent loss.

In an optical fiber link with polarization-dependent loss (PDL), we demonstrate that although the complex polarization mode dispersion vector cannot be fully obtained by the reflectometric measurement, the spectrally resolved differential group delay (DGD) and differential attenuation slope (DAS) can be explicitly determined by such measurements performed simultaneously in the optical frequency domain and the fiber length domain. In principle, this technique can be used to realize the spectrally resolved and spatially resolved measurement of DGD and DAS in an optical fiber link having PDL based on distributed Rayleigh backscattering. We report the experimental result based on the far-end Fresnel reflection to confirm the validity of the proposed method.

Coherence-free microwave photonic notch filter with a single driver intensity modulator in a Sagnac fiber loop.

A coherence-free microwave photonic filter configuration is presented. The configuration is based on a Sagnac loop interferometer containing a single-drive intensity modulator without a nonreciprocal bias unit. A notch response is obtained by modulating the clockwise and counterclockwise propagating waves inside the Sagnac loop at different times.

Cascaded dynamic eigenstates of polarization analysis for piezoelectric polarization control.

We propose the cascaded dynamic eigenstates (DESs) of polarization to analyze multicomponent polarization control (PC) devices, and achieve the analytical expression of output state of polarization (SOP) as a function of voltage for piezoelectric polarization control (PPC). By measuring the DES at the output port of the device, the prestage DESs will rotate around subsequent ones. Experimental results in PPC confirm the validity of our analysis.

High-resolution photonic bandgap fiber-based biochemical sensor.

The use of photonic bandgap fibers (PBGF) for biomedical sensing has been demonstrated. The demonstrated PBGF has a blue wavelength shift of 280 nm in the falling photonic bandgap edge (PBE) when the ambient refractive indices inside the holey region change from 1.333 to 1.

Spectral-resolved backreflection measurement of polarization mode dispersion in optical fibers.

An improved backreflection technique is proposed to perform the spectral-resolved measurement of polarization mode dispersion (PMD) in optical fibers. This technique is based on the PMD dynamical equation and realized by measuring the polarization state evolutions of the reflected signal in both frequency and time domains. Two experimental setups, employing the far-end Fresnel reflection, are constructed to verify this technique.

Ultrawideband monocycle generation using cross-phase modulation in a semiconductor optical amplifier.

We propose a novel scheme to generate ultrawideband (UWB) monocycle pulses based on cross-phase modulation (XPM) of a semiconductor optical amplifier (SOA). The proposed system consists of a SOA and an optical bandpass filter (OBF). Due to the XPM, a continuous wave (CW) probe signal is phase modulated by another optical Gauss pulse in the SOA.

Low-loss all-solid photonic bandgap fiber.

We report the fabrication and characterization of a new type all-solid photonic bandgap fiber. By introducing an index depressed layer around the high-index rod in the unit cell of photonic crystal cladding, transmission loss as low as 2 dB/km within the first bandgap is realized for the all-solid photonic bandgap fiber with a bandwidth of over 700 nm. The bend loss experiment shows that the photonic bandgap fiber is much less bend sensitive than single-mode fiber.

40 Gb/s all-optical NRZ to RZ format conversion using single SOA assisted by optical bandpass filter.

We propose a novel all-optical format conversion from nonreturn-to-zero (NRZ) to return-to-zero (RZ) based on single semiconductor optical amplifier (SOA) and a detuning optical bandpass filter (OBF). By adopting the ultrafast SOA model associated with intraband mechanism, the 40Gb/s NRZ-to-RZ format conversion is successfully demonstrated with numerical simulation. We investigate the influence of the filter detuning, extinction ratio, conversion efficiency, output pulsewidth, and filter bandwidth.

Measurement of the complex polarization mode dispersion vector using Jones matrix analysis.

The polarization mode dispersion (PMD) of a nondepolarizing optical system is analyzed. A new method is proposed to calculate the complex PMD vector by measuring two Jones matrices at two different wavelengths.

Simultaneous dual free spectral range microwave photonic filter using a high-birefringence chirped grating in a Sagnac loop.

We propose a continuously tunable, dual free spectral range (FSR) photonic microwave notch filter configuration using a high-birefringence linearly chirped fiber Bragg grating (Hi-Bi LCFBG) that is connected in a Sagnac loop using a Hi-Bi coupler. The configuration employs double sideband modulation and can generate two FSRs simultaneously. The larger FSR corresponds to the differential time delay of the Hi-Bi LCFBG and the Hi-Bi pigtails of the coupler; the smaller FSR corresponds to the time delay between the arms of the Sagnac loop.

Stable room-temperature multi-wavelength lasing realization in ordinary erbium-doped fiber loop lasers.

A suppressant effect for mode competition of multi-wavelength lasing oscillations induced by deeply saturated effect in an ordinary erbium-doped fiber ring laser (EDFRL) was observed and experimentally investigated. Results show that the effect is helpful to obtain stable multi-wavelength lasing at room temperature in the EDFRL, which offers a new and simple approach to achieve stable multi-wavelength EDF lasing. Stable two- and three- wavelength lasing oscillations were achieved based on the effect in the ordinary EDFRL for the first time to our best knowledge.

Experimental demonstration of both inverted and non-inverted wavelength conversion based on transient cross phase modulation of SOA.

We demonstrate experimentally ultrafast inverted and noninverted wavelength conversion (WC) based on a semiconductor optical amplifier (SOA) and an optical bandpass filter (OBF). In the case of small detuning, the WC is inverted regardless if the OBF is blue- or red-shifted with respect to the central wavelength of the converted signal. However the WC is non-inverted when the filter detuning is relatively large.

Symmetry properties of two-dimensional anisotropic photonic crystals.

A theoretical study of two-dimensional photonic crystals made of anisotropic material is presented. Detailed computation principles including a treatment of the TE and TM polarizations are given for a photonic crystal made of either uniaxially or biaxially anisotropic materials. These two polarizations can be decoupled as long as any one of the principal axes of the anisotropic material is perpendicular to the periodic plane of the photonic crystal.