Showing papers on "Extinction ratio published in 2004"
TL;DR: In this article, temperature-insensitive eye-opening under 10-Gb/s direct modulation of 1.3-µm p-doped quantum-dot lasers without using any current adjustments was demonstrated.
Abstract: We demonstrate temperature-insensitive eye-opening under 10-Gb/s direct modulation of 1.3-µm p-doped quantum-dot lasers without using any current adjustments. The lasers show a 6.5-dB extinction ratio between 20°C and 70°C. An active region consisting of ten quantum-dot layers with p-type doping enabled this highly temperature-stable dynamic performance, which was much superior to conventional 1.3-µm quantum-well lasers. These results make it possible to use uncooled 1.3-µm quantum-dot lasers without any current adjustments.
177 citations
TL;DR: An all-optical logical AND gate at 10 Gbit/s based on cross-gain modulation (XGM) in two cascaded semiconductor optical amplifiers (SOAs) is demonstrated.
Abstract: An all-optical logical AND gate at 10 Gbit/s based on cross-gain modulation (XGM) in two cascaded semiconductor optical amplifiers (SOAs) is demonstrated. Single-port-coupled SOAs are employed and specially designed to improve the output extinction ratio as well as the output performance of the logic operation. The output signal power and extinction ratio from the first-stage wavelength converter are critical to achieving all-optical logical AND operation.
133 citations
TL;DR: Numerical simulations with a full vectorial beam propagation method demonstrate that it is possible to obtain a 1.9-mm-long splitter with the extinction ratio better than -20 dB and a bandwidth of 37nm.
Abstract: A novel design of polarization splitter in three-core photonic crystal fibers (PCFs) has been proposed. The three-core PCF consists of two given identical cores with two-fold symmetry separated by a core with high birefringence. The polarization splitter is based on the phenomenon of resonant tunneling. Numerical simulations with a full vectorial beam propagation method demonstrate that it is possible to obtain a 1.9-mm-long splitter with the extinction ratio better than -20 dB and a bandwidth of 37 nm.
116 citations
TL;DR: In this article, sensitive nonlinear optical detection techniques are applied to the problem of performance monitoring and are shown to allow quantitative measurements to be made of quantities such as accumulated chromatic dispersion, polarization-mode dispersion impairment, optical signal-to-noise ratio, and extinction ratio.
Abstract: A definitive goal for optical performance monitoring in an optical communications network is to provide comprehensive signal quality information in a cost-effective manner. This paper explores in detail the possibility of using nonlinear optical detection to achieve this goal. Sensitive nonlinear detection techniques commonly used in the field of ultrafast optics are applied to the problem of performance monitoring and are shown to allow quantitative measurements to be made of quantities such as accumulated chromatic dispersion, polarization-mode dispersion impairment, optical signal-to-noise ratio, and extinction ratio. Experiments performed on a 40-Gb/s transmission system demonstrate the immediate viability of this approach for measuring these quantities of interest at practical optical power levels.
114 citations
TL;DR: In this article, a self-induced nonlinear polarization rotation in a semiconductor optical amplifier (SOA) is used to achieve all-optical logic for optical buffering at a bit rate of 10 Gb/s.
Abstract: We demonstrate novel optical signal processing functions based on self-induced nonlinear polarization rotation in a semiconductor optical amplifier (SOA). Numerical and experimental results are presented, which demonstrate that a nonlinear polarization switch can be employed to achieve all-optical logic. We demonstrate an all-optical header processing system, an all-optical seed pulse generator for packet synchronization, and an all-optical arbiter that can be employed for optical buffering at a bit rate of 10 Gb/s. Experimental results indicate that optical signal processing functions based on self-polarization rotation have a higher extinction ratio and a lower power operation compared with similar functions based on self-phase modulation.
97 citations
TL;DR: This work presents, for the first time to the authors' knowledge, a cw, all-fiber optical parametric oscillator that uses a holey fiber and can yield an oscillating parametric signal that consists of a single line with a 30-dB extinction ratio and a 10-pm linewidth.
Abstract: We present, for the first time to our knowledge, a cw, all-fiber optical parametric oscillator that uses a holey fiber. The oscillator operates at 1.55 µm and can yield an oscillating parametric signal that consists of a single line with a 30-dB extinction ratio and a 10-pm linewidth or that consists of multiple lines. In addition to the signal and the idler, five other pairs of spectral lines can be observed that are due to multiple parametric interactions. The source reaches threshold for a pump power of 1.28 W and saturates for pump powers in excess of ∼1.6 W.
81 citations
TL;DR: In this paper, a novel optical switches based on VO2 thin film on substrates of silicon (1.0-0) has been fabricated, and the vanadium dioxide thin films were deposited by reactive ion beam sputtering followed by a post-annealing.
81 citations
TL;DR: In this article, a 2×2 microfluidic-based optical switch is proposed and demonstrated, made of an optically clear silicon elastomer, Polydimethylsiloxane (PDMS), using soft lithography.
Abstract: A 2×2 microfluidic-based optical switch is proposed and demonstrated. The switch is made of an optically clear silicon elastomer, Polydimethylsiloxane (PDMS), using soft lithography. It has insertion loss smaller than 1 dB and extinction ratio on the order of 20 dB. The device is switching between transmission (bypass) and reflection (exchange) modes within less than 20 ms
78 citations
TL;DR: In this paper, a Mach-Zehnder electro-optic polymer amplitude modulator is fabricated by a simple and high-throughput soft-stamp replica-molding technique.
Abstract: A Mach-Zehnder electro-optic polymer amplitude modulator is fabricated by a simple and high-throughput soft-stamp replica-molding technique. The modulator structure incorporates the highly nonlinear and stable chromophore, AJL8, doped in amorphous polycarbonate. Single-arm phase-retardation results in a halfwave voltage (V-pi) of 8.4 V at 1600 nm. The on/off extinction ratio is better than 19 dB, resulting from precise Y-branch power splitters and good waveguide uniformity. These results indicate that the simple fabrication process allows for good optical performance from high-fidelity replicas of the original master devices.
75 citations
TL;DR: In this paper, an optical fiber sensor for liquid level detection is presented, which operates based on light intensity modulation, and such modulation results from alteration of total internal reflection into partial reflection at the interface.
73 citations
TL;DR: Numerical modeling based on the vectorial Maxwell equation reveals the dependence of the single-polarization bandwidth on core delta and air-hole size and a correlation between fiber birefringence and single- polarization operating bandwidth is qualitatively confirmed.
Abstract: An elliptical-core hole assisted single-polarization fiber was designed, fabricated, and characterized. Numerical modeling based on the vectorial Maxwell equation reveals the dependence of the single-polarization bandwidth on core delta and air-hole size. Several single-polarization fibers based on this design with their single-polarization operating windows centered between 0.9 and 1.5 µm were successfully demonstrated. A correlation between fiber birefringence and single-polarization operating bandwidth is qualitatively confirmed. A single-polarization bandwidth as high as 55 nm was observed. These fibers also show very high extinction ratios of 60 dB or higher at lengths much shorter than 1 m. Other properties such as the dependence on length of the single-polarization operating window were also measured.
TL;DR: In this paper, a novel technique for optical multiplexing of label and payload using optical carrier suppression and separation is proposed and experimentally demonstrated, where no power penalty is observed when the payload and label, with signal extinction ratio > 11 dB, are transmitted over 60-km standard single-mode fiber with full-dispersion compensation.
Abstract: A novel technique for optical multiplexing of label and payload using optical carrier suppression and separation is proposed and experimentally demonstrated. No power penalty is observed when the payload and label, with signal extinction ratio >11 dB, are transmitted over 60-km standard single-mode fiber with full-dispersion compensation. The technique of the optical label generation offers many advantages compared with previous techniques.
TL;DR: In this article, the polarization dependence of light coupling in photonic crystal fibers (PCFs) with sixfold symmetric dual cores and highly birefringent dual cores was numerically investigated.
Abstract: The polarization dependence of light coupling in photonic crystal fibers (PCFs) with sixfold symmetric dual cores and highly birefringent dual cores are numerically investigated. The characteristics of PCF-based couplers, such as coupling length, extinction ratio and form birefringence, are examined as functions of the air-hole size and pitch. The silica bridges between air holes take an important role in the energy transfer across the two cores. We believe that the mechanism of light coupling in PCF-based couplers is different from that of conventional waveguide couplers. The polarization dependent coupling can be reduced by adjusting the air holes around the cores of PCFs. On the other hand, the polarization dependent coupling can be enhanced by introducing high birefringence in the two cores.
01 Jul 2004
TL;DR: In this article, a high-speed all-silicon optical phase modulator with a metal-oxide-semiconductor (MOS) capacitance was proposed, which can be used to modulate the phase of the optical mode due to free-carrier plasma dispersion effect.
Abstract: We present design, fabrication, and testing of a high-speed all-silicon optical phase modulator in silicon-on-insulator (SOI). The optical modulator is based on a novel silicon waveguide phase shifter containing a metal-oxide-semiconductor (MOS) capacitor. We show that, under the accumulation condition, the drive voltage induced charge density change in the silicon waveguide having a MOS capacitor can be used to modulate the phase of the optical mode due to the free-carrier plasma dispersion effect. We experimentally determined the phase modulation efficiency of the individual phase shifter and compared measurements with simulations. A good agreement between theory and experiment was obtained for various phase shifter lengths. We also characterized both the low- and high-frequency performance of the integrated Mach-Zehnder interferometer (MZI) modulator. For a MZI device containing two identical phase shifters of 10 mm, we obtained a DC extinction ratio above 16 dB. For a MZI modulator containing a single-phase shifter of 2.5 mm in one of the two arms, the frequency dependence of the optical response was obtained by a small signal measurement. A 3-dB bandwidth exceeding 1 GHz was demonstrated. This modulation frequency is two orders of magnitude higher than has been demonstrated in any silicon modulators based on current injection in SOI.
Patent•
09 Jun 2004
TL;DR: The optical switching devices can include balanced demultiplexer/multiplexer combinations and switches that provide for uniform optical loss through the devices as mentioned in this paper, and low extinction ratio switches can be configured to provide higher extinction ratios.
Abstract: The optical systems of the present invention include optical switching device generally configured to control signal characteristic profiles over the pluralities of signal channels, or wavelengths, to provide desired signal characteristic profiles at the output ports of the device. Various signal characteristics that can be controlled include power level, cross-talk, optical signal to noise ratio, etc. The optical switching devices can include balanced demultiplexer/multiplexer combinations and switches that provide for uniform optical loss through the devices. In addition, low extinction ratio switches can be configured to provide higher extinction ratios.
TL;DR: In this paper, the properties of an all-optical 2R regenerator based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) are investigated.
Abstract: The properties of an all-optical 2R regenerator based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) are investigated. The regeneration is based on the nonlinear FWM transfer function and a study of the system's static behavior reveals the operating conditions, under which the transfer function approaches most the ideal, step-like discrimination characteristic function. A fiber Bragg grating (FBG) is employed in order to overcome the SOAs speed limitations due to limited carrier dynamics. The simulations with dynamic input data by means of extinction ratio (ER) and Q-factor calculations, showed satisfactory regenerative behavior up to 40 Gb/s.
TL;DR: In this paper, the beam splitter structure consists of two orthogonally crossed line defects and one point defect in square-lattice photonic crystals, and the point defect is positioned at the intersection of the line defects to divide the input power into output ports.
Abstract: This work studies two-dimensional photonic crystal beam splitters with two input ports and two output ports. The beam splitter structure consists of two orthogonally crossed line defects and one point defect in square-lattice photonic crystals. The point defect is positioned at the intersection of the line defects to divide the input power into output ports. If the position and the size of the point defect are varied, the power of two output ports can be identical. The beam splitters can be used in photonic crystal Mach-Zehnder interferometers or switches. The simulation results show that a large bandwidth of the extinction ratio larger than 20 dB can be obtained while two beams are interfered in the beam splitters. This enables photonic crystal beam splitters to be used in fiber optic communication systems.
TL;DR: The demonstration of an all-optical OR logic gate using the FPLD-based NRZ-to-PRZ transformer is reported and the best side-mode suppression ratio of 40 dB and the lowest timing jitter of 0.4 ps for the PRZ data-stream are observed.
Abstract: By using an optical nonreturn-to-zero (NRZ) format data-stream to injection-lock an synchronously modulated Fabry-Perot laser diode at below threshold condition (without DC driving current), an output data-stream with pseudo-return-to-zero (PRZ) format can be generated at bit rate of up to 2.488 Gbit/s. Such an NRZ-to-PRZ format transformation is due to the injection-locking induced gain-switching of the FPLD with the incoming NRZ data. The PRZ data-stream with a maximum on/off extinction ratio of 12.2 dB is obtained under the optical injecting power of -2 dBm and the RF driving power of 24.4 dBm. The best side-mode suppression ratio of 40 dB and the lowest timing jitter of 0.4 ps for the PRZ data-stream are observed. A power penalty of 1.2 dB is measured at a bit-error rate of 10-9 after NRZ-to-PRZ transformation. In application, the demonstration of an all-optical OR logic gate using the FPLD-based NRZ-to-PRZ transformer is also reported.
TL;DR: The GIRO PBS is theoretically and experimentally shown to be an adequate PBS for use as an optical isolator in combination with a quarter-wave plate in a CO2-laser system.
Abstract: A polarization beam splitter (PBS) based on a giant-reflection to zero-order (GIRO) grating is presented. The GIRO grating is a simple binary diffraction grating with parameters chosen such that the excited optical modes in the grating interfere constructively and destructively at the respective interfaces. This interference results in high-zero-order reflection (>99%) with a high polarization-selective extinction ratio (±30 dB). The grating shows a low aspect ratio. The GIRO PBS is theoretically and experimentally shown to be an adequate PBS for use as an optical isolator in combination with a quarter-wave plate in a CO2-laser system.
TL;DR: A simple and effective method for the postfabrication trimming of optical microresonators by photobleach CLD-1 chromophores to tune the resonance wavelengths of polymer microring resonator optical notch filters.
Abstract: We present a simple and effective method for the postfabrication trimming of optical microresonators. We photobleach CLD-1 chromophores to tune the resonance wavelengths of polymer microring resonator optical notch filters. A maximum wavelength shift of ~8.73 nm is observed. The resonators are fabricated with a soft-lithography molding technique and have an intrinsic Q value of 2.6 x 10^4 and a finesse of 9.3. The maximum extinction ratio of the resonator filters is ~34 dB, indicating that the critical coupling condition has been satisfied.
TL;DR: A novel broadband polarizing beam splitter with a compact sandwich structure that has a subwavelength grating in the quasi-static domain as the filling that can provide a high polarization extinction ratio in a broad spectral range is proposed.
Abstract: We propose a novel broadband polarizing beam splitter with a compact sandwich structure that has a subwavelength grating in the quasi-static domain as the filling. The design is based on effective-medium theory an anisotropic thin-film theory, and the performance is investigated with rigorous coupled-wave theory. The design results show that the structure can provide a high polarization extinction ratio in a broad spectral range.
TL;DR: In this paper, a low-loss wavelength selective switch was proposed and demonstrated with a 1/spl times/4 transversal filter configuration that includes arrayed waveguide gratings and thermo-optic phase shifters.
Abstract: A low loss wavelength-selective switch is proposed and demonstrated. The switch has a 1/spl times/4 transversal filter configuration that includes arrayed waveguide gratings and thermooptic phase shifters, and can route arbitrary wavelength input light to arbitrary outputs with no loss variation. We confirmed its operating principle and obtained an average loss of 2.7 dB and a worst extinction ratio of more than 20 dB.
TL;DR: In this article, an all-optical inverter using transverse mode switching of a 1.55/spl mu/m vertical-cavity surface-emitting laser is demonstrated.
Abstract: An all-optical inverter using transverse-mode switching of a 1.55-/spl mu/m vertical-cavity surface-emitting laser is demonstrated. When an external light is injected to a first high-order mode, the output power of the fundamental mode is strongly suppressed due to injection locking resulting in a large extinction ratio of over 20 dB. Waveform inversion is demonstrated for the input signal of a 5-GHz sinusoidal wave.
TL;DR: In this paper, the melting point and thermal stability of 0.62PMN-0.38PT single crystals were measured using simultaneous thermo-gravimetric analysis and differential thermal analysis.
TL;DR: In this paper, a multichannel fiber Bragg grating (FBG) design based on a discrete layer-peeling method is described, which enables us to design any kind of multichannels FBG in which the spectrum responses of the channels can be either identical or non-identical.
Abstract: A multichannel fiber Bragg grating (FBG) design based on a discrete layer-peeling method is described. This novel method enables us to design any kind of multichannel FBG in which the spectrum responses of the channels can be either identical or nonidentical. In particular, a nine-channel dispersion-free FBG and a nine-channel nonlinearly chirped FBG used simultaneously as chromatic dispersion and dispersion slope compensators are described. Unlike the general multichannel FBG designed by a sampling method, these two gratings have ideal flat-topped profiles in both the transmission and the reflection spectra. By optimally detuning the relative phases for the multiple-spectrum channels with an iterative layer-peeling method, we can make maximum use of length-limited photosensitive fiber. Moreover, we show numerically that one can reduce or eliminate the oscillation that inherently exists in the index-change envelope of our multichannel FBG by accepting a decreased extinction ratio of the in-band signal to the out-of-band noises.
TL;DR: In this paper, an optical bias controller is proposed to suppress cross-phase modulation between counterpropagating lights, which degrades the extinction ratio of nonlinear optical-loop-mirror switches.
Abstract: Cross-phase modulation between counterpropagating lights degrades the extinction ratio of nonlinear optical-loop-mirror (NOLM) switches. To suppress such effect, we propose an NOLM with an optical-bias controller that can give a proper amount of optical bias between lights propagating through an NOLM in opposite directions. Implementing such optical bias controller in a conventional NOLM composed of a polarization-maintaining fiber, we demonstrate, for the first time, wavelength conversion of a nonreturn-to-zero signal under the full-swing condition with the maximum extinction ratio.
TL;DR: The authors describe a general method to extract the frequency chirping of Mach-Zehnder modulators based on direct measurements of the output spectrum and allows measurement of the intrinsic chirp parameter to an accuracy of 5%.
Abstract: The authors describe a general method to extract the frequency chirping of Mach-Zehnder modulators based on direct measurements of the output spectrum. This method is independent of the modulator extinction ratio and allows measurement of the intrinsic chirp parameter to an accuracy of 5%.
TL;DR: In this article, a method for increasing the all-optical modulation bandwidth of SOAs by use of a cross-gain-modulated (XGM) holding signal is suggested and analyzed.
Abstract: A method for increasing the all-optical modulation bandwidth of semiconductor optical amplifiers (SOAs) by use of a cross-gain-modulated (XGM) holding signal is suggested and analyzed. The bandwidth improvement is numerically demonstrated by studying wavelength conversion in an SOA-based Mach-Zehnder interferometer (MZI) at 160 and 40 Gb/s. The new scheme is predicted to improve the extinction ratio and the minimum mark output power, as well as to reduce the amplitude jitter of the wavelength converted signal.
TL;DR: It is shown that the input signal wavelength can be simultaneously converted to 6 different wavelengths at 10 Gb/s with signal regeneration with wavelength multicasting using cross-absorption modulation in a single electroabsorption modulator for the first time.
Abstract: All-optical signal regeneration with wavelength multicasting has been demonstrated using cross-absorption modulation in a single electroabsorption modulator for the first time. We show that the input signal wavelength can be simultaneously converted to 6 different wavelengths at 10 Gb/s with signal regeneration. The output extinction ratio, the linewidth, and the pulse shape show a significant improvement. A negative power penalty of 2 dB is obtained at 10-9 bit-error-rate level.
Patent•
22 Jan 2004
TL;DR: In this article, an automatic closed loop power control system is described for simultaneously adjusting an output power and an extinction ratio P 1 /P 0 of a laser diode in order to maintain a desired average output power.
Abstract: An automatic closed loop power control system is described for simultaneously adjusting an output power and an extinction ratio P 1 /P 0 of a laser diode in order to maintain a desired average output power and a desired extinction ratio. The bias current component of a laser diode drive current is adjusted to compensate for changes in the average output power caused by ambient characteristics such as temperature and aging. Simultaneously, a modulation current component of the laser diode drive current is adjusted to maintain an extinction ratio of the laser diode output signal. The bias current and modulation current adjustments are based on the second order statistics of an average output power of the laser diode and a variance in the power output of the laser diode.