Showing papers on "Extinction ratio published in 2002"
TL;DR: In this article, the chirp of a dual-drive Mach-Zehnder (MZ) modulator with a finite DC extinction ratio was measured using the fiber response peak method and compared with the theoretically calculated values.
Abstract: In this letter, we present theoretical and experimental studies on the chirp of the dual-drive Mach-Zehnder (MZ) modulator with a finite DC extinction ratio. The chirp of the modulator was measured using the fiber response peak method and compared with the theoretically calculated values. The results show that the residual chirp of the MZ modulator could be substantially reduced by driving the modulator in a push-pull mode with unequal amplitude signals.
104 citations
TL;DR: In this paper, the authors analyzed the switching characteristics of multimode interference photonic switches (MIPS) by wide-angle finite difference beam propagation method (FD-BPM) and found that MIPS with a length of 599 /spl mu/m can switch the output light polarization insensitively with a crosstalk of less than -20 dB for a wavelength range of 70 nm.
Abstract: The switching characteristics of multimode interference photonic switches (MIPS) are analyzed by wide-angle finite difference beam propagation method (FD-BPM). As a result, it is found that the MIPS with a multimode interference (MMI) length of 599 /spl mu/m can switch the output light polarization insensitively with a crosstalk of less than -20 dB for a wavelength range of 70 nm. These analyses show that the MIPS can also have a 3-dB coupler function. Experimentally, an InGaAsP/InP 1/spl times/2 MIPS with a thicker InP cladding layer was fabricated and exhibited switching operation with crosstalks of -8 dB and -10 dB at 0 and 20 mA current injections, respectively. For a 2/spl times/2 MIPS with a thinner InP cladding layer, better switching characteristics with a crosstalk of -13 dB and an extinction ratio of 17 dB were realized.
81 citations
TL;DR: In this article, a two-cascaded semiconductor optical amplifiers (SOAs) in a counter-propagating feedback configuration were used for all-optical logic NOR gates.
Abstract: The authors present a novel all-optical logic NOR gate using two-cascaded semiconductor optical. amplifiers (SOAs) in a counterpropagating feedback configuration. This configuration accentuates the gain nonlinearity due to the mutual gain modulation of the two SOAs. The all-optical NOR gate feasibility has been demonstrated delivering an extinction ratio higher than 12 dB over a wide range of wavelength.
79 citations
TL;DR: In this paper, a complex-coupled distributed feedback (DFB) grating is used to enable high output power for long-span EMLs, and the effect of a bias-dependent alpha parameter is analyzed.
Abstract: Strain-compensated AlGaInAs quantum-well electroabsorption modulated lasers (EMLs) transmit at 10 Gbits/s on uncompensated transmission spans of >75 km of standard fiber and >225 km of MetroCor fiber. Details of the design, fabrication, and testing are presented. A complex-coupled distributed feedback (DFB) grating is used to enable high output power. The epitaxy and chip structure are described. The paper studies what is needed to accomplish long-span transmission in terms of minimum physical requirements for laser mode control, facet reflection, index grating strength, laser-modulator matching, laser-modulator electrical isolation, modulator extinction ratio, modulator capacitance, linewidth enhancement factor, etc. The interaction of the modulator with the laser is analyzed and a requirement for this structure is computed for the electrical isolation resistance between modulator and laser contacts. Stability of the laser source is discussed and a method is derived for determining the grating's gain-coupling coefficient at operating power. Chirp due to the modulator is analyzed. Nonzero chirp of the modulator is shown to have beneficial impact on the quality of the signal after transmission. The effect of a bias-dependent alpha parameter is analyzed. Because bit-error rate is a strong function of mean alpha parameter and not a strong function of the range of alpha during nonreturn-to-zero modulation, we determine that tuning the chirp of the EML modulator to suit different fiber types (MetroCor, SMF-28, etc.) is practical. Specific tradeoffs are also required. Experimental results verify the analysis.
79 citations
TL;DR: In this article, an InGaAsP multiquantum-well traveling-wave electroabsorption modulator with high extinction ratio and modulation efficiency is demonstrated with high saturation power (>14 dBm) for >20 GHz high-speed performance (1.5 dB drop at 20 GHz) is achieved.
Abstract: An InGaAsP multiquantum-well traveling-wave electroabsorption modulator is demonstrated with high extinction ratio and modulation efficiency. By designing a strain-compensated quantum-well active region with traveling-wave design, high saturation power (>14 dBm) for >20-GHz high-speed performance (1.5 dB drop at 20 GHz) is achieved. Due to high modulation efficiency (>30 dBN for 0 to 1 V 40-dB extinction ratio in 2 V), error free 10-Gb/s operation with 1 V/sub p-p/ driving voltage is obtained. By comparing codirections and counterdirections of optical and microwave interactions, pulse generation at 40 GHz shows that the traveling-wave performance has an advantage for short pulses with high-power output, where pulsewidth as short as 4.5 ps is obtained in this kind of device.
69 citations
TL;DR: In this article, the authors proposed a novel structure that reduces the switching power of a silica-based thermooptic switch, which consists of silicon trenches and heat insulating grooves, which are formed beneath and beside the arms of a Mach-Zehnder interferometer.
Abstract: We propose a novel structure that reduces the switching power of a silica-based thermooptic switch (TOSW). The structure consists of silicon trenches and heat insulating grooves, which are formed beneath and beside the arms of a Mach-Zehnder interferometer, respectively. We optimize the structure using the differential-element method (DEM) and fabricate a 2 /spl times/ 2 TOSW with a switching power of only 90 mW, namely, 75% less than that of a conventional TOSW. We also obtain an insertion loss of about 1 dB and an extinction ratio of over 30 dB with a response time from 0% to 90% of 4.9 ms. We then use the structure to fabricate an 8 /spl times/ 8 matrix switch and confirm a total power consumption of 1.4 W with an average insertion loss of 7.4 dB and an extinction ratio of 50.4 dB for 64 possible optical paths.
63 citations
TL;DR: In this paper, a very short-reach optical link with 1.40 Gbit/s direct modulation of a 1.3 /spl mu/m distributed feedback laser is reported.
Abstract: 40 Gbit/s direct modulation of a 1.3 /spl mu/m distributed feedback laser is reported for very-short-reach optical links. Error-free operation is accomplished by using a negative dispersion fibre.
55 citations
TL;DR: In this paper, an all-optical Mach-Zehnder modulator was demonstrated which is composed of a polymer waveguide doped with a photochromic dye in the core and a thick light blocking metal layer on it.
Abstract: An all-optical Mach–Zehnder modulator is demonstrated which is composed of a polymer waveguide doped with a photochromic dye in the core and a thick light blocking metal layer on it. The metal layer was opened on one arm of the Mach–Zehnder modulator, so that only one arm of the modulator could be irradiated by modulation light, thus allowing a differential phase shift. The optical modulator exhibited an extinction ratio of about −12 dB at a wavelength of 1.55 μm. A simple kinetic model developed to delineate the refractive index change in the dye-doped polymer film was applied to predict the evolution of the modulation characteristics.
55 citations
Patent•
31 Oct 2002
TL;DR: In this paper, a method of maintaining desirable optical performance of optical emitters over temperature variations is disclosed, in terms of power, extinction ratio, jitter, mask margin and general fiber optic transmitter eye quality.
Abstract: A method of maintaining desirable optical performance of optical emitters over temperature variations is disclosed. The optical performance of an optical emitter in terms of power, extinction ratio, jitter, mask margin and general fiber optic transmitter eye quality can be maintained by the present invention over a wide range of temperatures. Advantageously, the present invention enables the use of inexpensive optical emitters in optoelectronic transceivers and optoelectronic transmitters.
50 citations
17 Mar 2002
TL;DR: In this article, the performance of the MEM-ECLSTM was evaluated for optical power, side mode suppression, polarization extinction ratio, relative intensity noise, and linewidth.
Abstract: In summary, silicon deep reactive ion etched (DRIE) MEMS actuators have enabled a small form factor, tunable laser source ideal for many DWDM applications. The performance of the MEM-ECL meets telecommunications requirements for optical power, side mode suppression, polarization extinction ratio, relative intensity noise, and linewidth. Frequency accuracy of /spl plusmn/1.25 GHz is obtained with closed loop control of the MEMS actuator voltage. Substantial immunity from external temperature fluctuations and vibrations can be achieved through a combination of thermo-mechanical design and servo control.
50 citations
TL;DR: In this paper, the effects on optical signal quality of passage through a cascade of wavelength division multiplexing (WDM) filters-multiplexers and demultiplexers-for directly modulated lasers with different chirp characteristics are investigated, and they find clear differences between the laser types with respect to filter concatenation effects.
Abstract: We report computer simulation results of the effects on optical signal quality of passage through a cascade of wavelength division multiplexing (WDM) filters-multiplexers and demultiplexers-for directly modulated lasers with different chirp characteristics. In particular, lasers with transient or adiabatic chirp characteristics at 2.5 Gb/s and 10 Gb/s are investigated, and we find clear differences between the laser types with respect to filter concatenation effects. Filters with an optical bandwidth suitable for a 200-GHz channel-spacing system are considered, and we evaluate the system behavior as a function of laser frequency offset for a fixed number of filters. The reference network architecture used for the simulations is an optically transparent metropolitan scale network in which the WDM signals may be demultiplexed and then multiplexed again at multiple optical network elements. The signal quality is evaluated in terms of a distortion-induced eye-closure penalty as well as the excess attenuation or loss suffered. We find that transient chirp-dominated lasers show a generally symmetric distortion penalty response to laser frequency offset, whereas the response for adiabatic chirp dominated lasers is highly asymmetric. Furthermore, the extinction ratio for the latter class of lasers can be improved, in some cases, by the appropriate offset between laser and filter center frequencies.
TL;DR: In this paper, a dual-wavelength injection locking of a Fabry-Perot (FP) laser diode was used for non-return-to-zero (NRZ) to return-tozero (RZ) data format and wavelength conversion.
TL;DR: Global maxima of diffraction efficiency for surface-corrugated gratings with binary, sinusoidal, and pyramidal ridge shapes with dependence on the material index are identified.
Abstract: The working principle of an optical isolator made of two corrugated dielectric gratings is introduced. One grating acts as a polarizer, and the other acts as a quarter-wave plate used in conical incidence converting linearly polarized light into circularly polarized light. Global maxima of diffraction efficiency for surface-corrugated gratings with binary, sinusoidal, and pyramidal ridge shapes with dependence on the material index are identified. Regarding technological feasibility for use in the visible wavelength range, high-frequency gratings with a binary shape were realized. With these gratings, an extinction ratio of more than 40 dB for the polarizer is theoretically possible, and more than 20 dB was experimentally achieved. A good correlation between theoretically calculated efficiencies and birefringences based on rigorous methods and the experimental results is demonstrated.
TL;DR: In this paper, a metal-organic-chemical-vapordeposition-grown low-optical-insertion-loss InGaAsP/InP multiple-quantum-well electroabsorption modulator (EAM) is presented for both nonreturn-to-zero (NRZ) and return-tozero (RZ) applications.
Abstract: We present a metal-organic-chemical-vapor-deposition-grown low-optical-insertion-loss InGaAsP/InP multiple-quantum-well electroabsorption modulator (EAM), suitable for both nonreturn-to-zero (NRZ) and return-to-zero (RZ) applications. The EAM exhibits a dynamic (RF) extinction ratio of 11.5 dB at 1550 nm for 3 Vp-p drive under 40-Gb/s modulation. The optical insertion loss of the modulator in the on-state is -5.2 dB at 1550 nm. In addition, the EAM also exhibits a 3-dB small-signal response (S21) of greater than 38 GHz, allowing it to be used in both 40-Gb/s NRZ and 10-Gb/s RZ applications. The dispersion penalty at 40 Gb/s is measured to be 1.2 dB over /spl plusmn/40 ps/nm of chromatic dispersion. Finally, we demonstrate 40-Gb/s transmission performance over 85 km and 700 km.
07 Aug 2002
TL;DR: In this paper, a multi-channel modulation circuit with one 25 GHz-spacing AWG for both MUX and DEMUX and eight channels of SOAs and EAMs is presented.
Abstract: We present a multi-channel modulation circuit monolithically integrated with one 25-GHz-spacing AWG for both MUX and DEMUX and eight channels of SOAs and EAMs. The circuit can generate individual optical signals for each DWDM channel with a high extinction ratio of >20 dB and loss compensation. The circuit size can be reduced to 15 /spl times/ 7 mm/sup 2/.
10 Nov 2002
TL;DR: In this article, the first transmission experiment with all-optically labelled packets consisting of ASK modulated payload and orthogonally modulated DPSK label is demonstrated and the limitation of the laser linewidth and the input extinction ratio are discussed.
Abstract: First transmission experiment with all-optically labelled packets consisting of ASK modulated payload and orthogonally modulated DPSK label is demonstrated. The limitation of the laser linewidth and the input extinction ratio are discussed.
TL;DR: In this article, an optical modulator based on an InGaAlAs/InGaAlAlAs multiple quantum well (MQW) structure was demonstrated, which had an extinction ratio 6 dB higher than that of a conventional InGaAsP-based device with similar chirp behaviour.
Abstract: An optical modulator based on an InGaAlAs/InGaAlAs multiple quantum well (MQW) structure is demonstrated. The fabricated device had an extinction ratio 6 dB higher than that of a conventional InGaAsP-based device with similar chirp behaviour. The InGaAlAs MQW effectively improved the performance trade-off between the extinction ratio and chirping parameter.
TL;DR: In this article, the authors proposed a cell-AGC technique for an ATM-cell-based burst optical receiver on a 156-Mb/s subscriber system, which enables reception of burst signals with low extinction ratio.
Abstract: We propose a novel cell-AGC technique for an ATM-cell-based burst optical receiver on a 156-Mb/s subscriber system. The cell-AGC controls transimpedance gain according to the burst-cell power and enables reception of burst signals with low extinction ratio. In addition, to realize high sensitivity, we developed an amplifier that is stable under changes in ambient conditions and deviations of transistor characteristics on IC. By adopting these techniques in a CMOS preamplifier IC, the detectable power difference between burst cells was enlarged to more than 30 dB, and the minimum sensitivity was improved to less than -39.3 dBm. These performances show that our new IC fully satisfies the high-sensitivity specification of an ATM-PON system, and incorporating this IC in the system makes it more flexible and economical.
TL;DR: In this article, an integrated Mach-Zehnder interferometer containing a monomodal semiconductor optical amplifier (SOA) and an SOA with a 1 /spl times/ 1 multimode interference coupler-SOA was proposed.
Abstract: 2R regeneration is proposed with an integrated Mach-Zehnder interferometer containing a monomodal semiconductor optical amplifier (SOA) and an SOA with a 1 /spl times/ 1 multimode interference (MMI) coupler-SOA in the arms. Simulations and measurement of the static transfer function show a digital shape with a high extinction ratio improvement.
TL;DR: In this paper, an improvement of pulse extinction ratio from 15-20 dB to approximately 40 dB of a 10-GHz pulse train is demonstrated using the self-phase modulation-induced spectral shift caused by a semiconductor optical amplifier (SOA).
Abstract: Improvement of pulse extinction ratio from 15-20 dB to approximately 40 dB of a 10-GHz pulse train is demonstrated using the self-phase modulation-induced spectral shift caused by a semiconductor optical amplifier (SOA). The improvement permits penalty-free optical time-division multiplexing to 40 Gb/s, and demultiplexing back to 10 Gb/s of an intentionally distorted signal. Without using the SOA the 40-Gb/s signal is not receivable.
TL;DR: In this paper, it was shown that the optical filtering of the ASE noise can have a strong impact on the signal-ASE beat noise and remarkably affect the power penalty, even for optical filter bandwidths five times wider than the signal bandwidth.
Abstract: The assessment of the power penalty of optically preamplified receivers with signal-dependent noise (SDN) dominance is often accomplished by neglecting the influence of the optical filtering of the amplified spontaneous emission (ASE) noise on the signal-ASE beat noise. In this paper, it is shown that the optical filtering of the ASE noise can have a strong impact on the signal-ASE beat noise and remarkably affect the power penalty, even for optical filter bandwidths five times wider than the signal bandwidth. A simple expression to analytically evaluate the power penalty due to optical filtering, which describes reasonably well the influence of the optical filter on the signal-ASE beat noise variance, is proposed. The accuracy of the new expression is investigated, in the case of assessment of the optical filter detuning impact on receiver performance and the case of optical filter bandwidth optimization, and its predictions are satisfactory in comparison with rigorous estimates. Two new expressions of power penalty due to extinction ratio and to eye closure are also presented. It is shown that the power penalty due to eye closure depends on the extinction ratio and vice versa. Our results show also that the power penalty due to eye closure is remarkably dependent on the eye closure asymmetry.
Proceedings Article•
01 Jan 2002TL;DR: In this article, an interferometric wavelength converter with power monitor was integrated with a digitally tunable 4-channel laser for the first time and converted signals showed excellent static extinction ratios of over 20 dB.
Abstract: An interferometric wavelength converter with power monitor has been monolithically integrated with a digitally tunable 4-channel laser for the first time. Converted signals showed excellent static extinction ratios of over 20 dB
TL;DR: In this article, a multisection grating-assisted coupler sampled reflector laser was used for simultaneous wavelength conversion and high-speed wavelength switching with a high output extinction ratio over a 30-nm wavelength range.
Abstract: Simultaneous wavelength conversion and high-speed wavelength switching has been demonstrated using a multisection grating-assisted coupler sampled reflector laser. A high-output extinction ratio (>20 dBm) over a 30-nm wavelength range was observed. The 10-Gb/s data was switched between different output wavelengths at a 2.5-Gb/s rate and transmitted over 50 km of dispersion-shifted fiber with a small measured power penalty (<2 dB).
Patent•
NEC1
TL;DR: In this article, a light receiving element is converted to a signal voltage by an amplifier and the gain of the amplifier is regulated by a transistor, which is outputted from an amplitude control circuit according to the difference between the DC voltage and a reference voltage.
Abstract: Provided is an optical receiving device which can achieve a wide dynamic range while keeping a constant extinction ratio against the changes in the input amplitude. A signal current of a light receiving element is converted to a signal voltage by an amplifier and the gain of the amplifier is regulated by a transistor. A DC voltage corresponding to the peak value of the signal current detected by a current detection circuit is outputted to a dummy current generating circuit. The resistance value of the transistor is controlled by a control voltage, which is outputted from an amplitude control circuit according to the difference between the DC voltage and a reference voltage, thereby to set the amplitude of the signal voltage converted by the amplifier to be invariable.
Proceedings Article•
01 Jan 2002
TL;DR: In this article, the transmission characteristics of a two-level optically labeled signal with ASK/DPSK modulation under varying dispersion management are investigated, and a limitation of extinction ratio and the resilience of fiber span, compensation ratio, and power level are obtained.
Abstract: The transmission characteristics of a two-level optically labeled signal with ASK/DPSK modulation are investigated under varying dispersion management. A limitation of extinction ratio and the resilience of fiber span, compensation ratio, and power level are obtained
TL;DR: In this article, a single-frequency and single-polarized distributed feedback (DFB) fiber laser by stress-induced phase shift birefringence was demonstrated and the corresponding theoretical analysis was presented.
TL;DR: In this article, a true digital-like optical decision characteristic with an adjustable decision threshold has been found for the all-optical 2R regenerator based on a Mach-Zehnder interferometer with gain-clamped semiconductor optical amplifiers.
Abstract: In this letter, we experimentally demonstrate improved static and dynamic characteristics of the all-optical 2R regenerator based on a Mach-Zehnder interferometer with gain-clamped semiconductor optical amplifiers. A true digital-like optical decision characteristic with an adjustable decision threshold has been found. A tremendous noise suppression at the logic "0" and a large improvement in the extinction ratio have been obtained even for a very deteriorated input signal with small extinction ratio at a bit rate of 2.488 Gb/s. An 8-dB improvement in extinction ratio can be achieved for an input extinction ratio of 5- and 7-dB improvement for an input extinction ratio of 2 dB. Furthermore, a good regeneration is achieved over a broad wavelength range of 20 nm.
17 Mar 2002
TL;DR: In this paper, a 40 Gb/s EAM-DFB module is proposed for short distance fiber transmission with a record high modulation bandwidth of 45 GHz and dynamic extinction ratio of 9 dB at Vpp of 3.9 V.
Abstract: A record high modulation bandwidth of over 50 GHz has been achieved for EAM-DFB lasers in the chip-on-carrier level by optimizing the device parameters. The packaged module has shown a record high modulation bandwidth of 45 GHz and dynamic extinction ratio of 9 dB at Vpp of 3.9 V. The 40 Gb/s NRZ-signal 4 km-transmission with standard SM fiber has been demonstrated. This 40 Gb/s EAM-DFB module is believed very promising for 40 Gb/s short distance fiber transmission.
TL;DR: In this article, a thin liquid crystal (LC) array for use as simple polarization-controller arrays on planar light-wave circuits (PLCs) was developed, which can switch the polarization of input light between the TE and TM modes with an extinction ratio of 15 dB.
Abstract: In this letter, we have developed thin liquid crystal (LC) arrays for use as simple polarization-controller arrays on planar lightwave circuits (PLCs). The 30-/spl mu/m thick LC arrays are vertically inserted into trenches cut across PLC substrates. Two such LC cells that are in line and parallel to each other, one of which has a direction of alignment that is rotated by 45/spl deg/ relative to that of the other, are able to convert an arbitrary input polarization to a desired one. Twisted-nematic LC cells can switch the polarization of input light between the TE and TM modes with an extinction ratio of 15 dB.
TL;DR: In this article, a novel all-optical 2R regenerator based on a multimode interference coupler (MMI) optical amplifier is presented, which has a high tolerance to the MMI length.
Abstract: A novel all-optical 2R regenerator based on a multimode interference coupler (MMI) semiconductor optical amplifier is presented. Static measurements of the transfer function reveal a digital transfer characteristic and a high increase in extinction ratio. The experiments are in good agreement with simulations, which have been done using a modified beam propagation method program. The device has a high tolerance to the MMI length. It has been fabricated in an all-active layout, avoiding the need for active/passive integration and is very compact.