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Showing papers in "IEEE Photonics Technology Letters in 2001"


Journal ArticleDOI
TL;DR: In this paper, the cutoff properties of birefringent photonic crystal fibers with respect to multimode behavior were analyzed theoretically and experimental results were presented in agreement with theoretical predictions.
Abstract: Photonic crystal fibers (PCFs) offer new possibilities of realizing highly birefringent fibers due to a higher intrinsic index contrast compared to conventional fibers. In this letter, we analyze theoretically the levels of birefringence that can be expected using relatively simple PCF designs. While extremely high degrees of birefringence may be obtained for the fibers, we demonstrate that careful design with respect to multimode behavior must be performed. We further discuss the cutoff properties of birefringent PCFs and present experimental results in agreement with theoretical predictions on both single- and multimode behavior and on levels of birefringence.

507 citations


Journal ArticleDOI
TL;DR: In this paper, the performance of a LiNbO/sub 3/ integrated modulator consisting of four phase modulator waveguides was analyzed for a 10 GHz single-tone signal with a driving voltage of 6.3 V/sub p-p/p/
Abstract: Single side-band (SSB) technologies are especially useful in optical fiber communication systems, such as higher density wavelength multiplexing and long-haul fiber transmission due to less nonlinear optical effects, because of the reduced optical power. This letter reports on the SSB modulation performance of a LiNbO/sub 3/ integrated modulator consisting of four phase modulator waveguides. Optical SSB modulation with suppressions of main carrier (-22.6 dB) and J/sub 3/ subcarrier (-18.4 dB) of a 10-GHz single-tone signal with a driving voltage of 6.3 V/sub p-p/ was demonstrated. The total insertion loss was 10.6 dB.

270 citations


Journal ArticleDOI
TL;DR: A broadband continuous-wave (CW) pumped fiber-based parametric amplifier with 39 dB of internal gain and wavelength conversion efficiency, corresponding to a black box gain/efficiency of 38 dB, is demonstrated in this article.
Abstract: A broad-band continuous-wave (CW) pumped fiber-based parametric amplifier with 39 dB of internal gain and wavelength conversion efficiency, corresponding to a black box gain/efficiency of 38 dB, is demonstrated. Bit-error-rate (BER) measurements indicate performance comparable to erbium-doped fiber amplifiers (EDFAs). These amplifiers may thus find new applications in future lightwave systems.

248 citations


Journal ArticleDOI
TL;DR: In this paper, the quantum-dot (QD) excited state carriers were found to act as a reservoir for the optically active ground state carriers resulting in an ultrafast gain recovery as long as the excited state is well populated.
Abstract: Measurements of ultrafast gain recovery in self-assembled InAs quantum-dot (QD) amplifiers are explained by a comprehensive numerical model. The QD excited state carriers are found to act as a reservoir for the optically active ground state carriers resulting in an ultrafast gain recovery as long as the excited state is well populated. However, when pulses are injected into the device at high-repetition frequencies, the response of a QD amplifier is found to be limited by the wetting-layer dynamics.

238 citations


Journal ArticleDOI
TL;DR: In this paper, the first self-assembled InAs quantum dash lasers grown by molecular beam epitaxy on InP (001) substrates were reported, with wavelengths from 1.60 to 1.66 μm for one-, three-, and five-stack designs, a threshold current density as low as 410 A/cm2 for singlestack uncoated lasers, and a distinctly quantumwire-like dependence of the threshold current on the laser cavity orientation.
Abstract: The first self-assembled InAs quantum dash lasers grown by molecular beam epitaxy on InP (001) substrates are reported. Pulsed room-temperature operation demonstrates wavelengths from 1.60 to 1.66 μm for one-, three-, and five-stack designs, a threshold current density as low as 410 A/cm2 for singlestack uncoated lasers, and a distinctly quantum-wire-like dependence of the threshold current on the laser cavity orientation. The maximal modal gains for lasing in the ground-state with the cavity perpendicular to the dash direction are determined to be 15 cm–1 for single-stack and 22 cm–1 for five-stack lasers.

223 citations


Journal ArticleDOI
TL;DR: In this article, a simple technique for monitoring the optical signal-to-noise ratios (OSNRs) of wavelength-division-multiplexed (WDM) signals is presented.
Abstract: We report on the simple technique for monitoring the optical signal-to-noise ratios (OSNRs) of wavelength-division-multiplexed (WDM) signals. This technique, based on the polarization-nulling method, was implemented simply by using a rotating quarter-wave plate and rotating linear polarizer. However, the performance of this technique could be affected by nonlinear birefringence and polarization-mode dispersion (PMD). The result shows that this technique is suitable for monitoring the OSNRs of highspeed (>10-Gb/s) WDM signals transported over the fiber link with low PMD.

208 citations


Journal ArticleDOI
TL;DR: In this paper, a symmetric-Mach-Zehnder (SMZ)-type switch was used to achieve error-free all-optical wavelength conversion at 168 Gb/s, which is the highest repetition rate ever reported.
Abstract: Error-free all-optical wavelength conversion at 168 Gb/s, which is the highest repetition rate ever reported, has been achieved by using a symmetric-Mach-Zehnder (SMZ)-type switch. Low-power-penalty 84-Gb/s operation is also demonstrated. The push-pull switching mechanism of the SMZ switch enables such ultrafast operation based on cross-phase modulation associated with the carrier depletion in a semiconductor optical amplifier. The configuration of the delayed-interference signal-wavelength converter, which is a simplified variant of the SMZ switch, is used in this experiment.

190 citations


Journal ArticleDOI
TL;DR: In this article, the authors observed a high-brightness laser beam emitted from a closely packed array of seven Yb-doped single-mode fiber lasers embedded in a common cladding.
Abstract: We observed a high-brightness laser beam emitted from a closely packed array of seven Yb-doped single-mode fiber lasers embedded in a common cladding. The measured slope efficiency, greater than 65%, was achieved by clad-pumping from one end of the fiber. A theoretical model is established to provide a physical interpretation of the measured far field radiation patterns.

186 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe the fabrication and initial testing of a novel optically interrogated, microelectromechanical system (MEMS) pressure sensor in which the entire MEMS structure is fabricated directly on an optical fiber and a new micromachining process for use on a flat fiber end face that includes photolithographic patterning, wet etching of a cavity and anodic bonding of a silicon diaphragm is utilized.
Abstract: We describe the fabrication, and initial testing of a novel optically interrogated, microelectromechanical system (MEMS) pressure sensor in which the entire MEMS structure is fabricated directly on an optical fiber A new micromachining process for use on a flat fiber end face that includes photolithographic patterning, wet etching of a cavity, and anodic bonding of a silicon diaphragm is utilized. We have employed both 200- and 400-/spl mu/m-diameter multimode optical fibers. A pressure sensor fabricated on an optical fiber has been tested displaying an approximately linear response to static pressure (0-80 psi). This sensor is expected to find application in situations where small size is advantageous and where dense arrays may be useful.

180 citations


Journal ArticleDOI
TL;DR: In this paper, a 750-Hz linewidth singlemode erbium-doped fiber (EDF) ring laser with wide tunability using a widely tunable fiber Bragg grating was demonstrated.
Abstract: We demonstrate a 750-Hz linewidth single-mode erbium-doped fiber (EDF) ring laser with wide tunability using a widely tunable fiber Bragg grating (FBG). The stable single-mode operation is realized by using the FBG as a narrow wavelength-selective element and 4 m of unpumped EDF as a saturable absorber in the cavity. The 40-nm continuous tuning range of 1522-1562 nm is achieved using a highly stretchable FBG that exhibits a filter tuning range of over 52 nm. The grating is prepared with chemically stripped deuterium-loaded fiber to eliminate degrading factors for the grating strength, thereby achieving the wide tunability. The tuning range represents a 3.5-fold increase in wavelength tuning over previous use of FBGs.

178 citations


Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate a novel high-sensitivity pressure sensor based on the use of a fiber Bragg grating (FBG) embedded in a polymer-filled metal cylinder with an opening on one side to enhance the pressure sensitivity.
Abstract: We demonstrate a novel high-sensitivity pressure sensor, which is based on the use of a fiber Bragg grating (FBG) embedded in a polymer-filled metal cylinder with an opening on one side to enhance the pressure sensitivity. The measured pressure sensitivity of the fractional change in the Bragg wavelength of our experimental sensor is -3.41/spl times/10/sup -3/ MPa/sup -1/ which is approximately 1720 times higher than that can be achieved with a bare FBG. The linearity of our sensor is also good. This sensor should find applications in the area of low-pressure measurement.

Journal ArticleDOI
Antonio Mecozzi1, Carl Balslev Clausen2, Mark Shtaif2, Sang-Gyu Park2, Alan H. Gnauck2 
TL;DR: In this paper, the authors study the properties of symmetric dispersion compensation in optical links using highly dispersed pulse transmission and show that by splitting the dispersion compensated equally between the input and output of the link, complete cancellation of the timing and amplitude jitter can be obtained in systems where the power profile is symmetric about the center.
Abstract: We study the properties of symmetric dispersion compensation in optical links using highly dispersed pulse transmission. We show analytically that by splitting the dispersion compensation equally between the input and output of the link, complete cancellation of the timing and amplitude jitter can be obtained in systems where the power profile is symmetric about the center. We explain the dynamics of this cancellation and show, theoretically and experimentaily, that with practical system parameters, symmetric compensation may lead to a considerable improvement in performance.

Journal ArticleDOI
TL;DR: In this article, a GaN-based metal-semiconductor-metal (MSM) photodetector with ITO transparent contacts was fabricated and a maximum 0.12-A photocurrent with a photocurrent to dark current contrast higher than five orders of magnitude during ultraviolet irradiation was obtained.
Abstract: Indium-tin-oxide (ITO) layers were deposited onto n-GaN films and/or glass substrates by electron-beam evaporation. With proper annealing, we found that we could improve the optical properties of the ITO layers and achieve a maximum transmittance of 98% at 360 nm. GaN-based metal-semiconductor-metal (MSM) photodetectors with ITO transparent contacts were also fabricated. A maximum 0.12-A photocurrent with a photocurrent to dark current contrast higher than five orders of magnitude during ultraviolet irradiation were obtained for a photodetector annealed at 600/spl deg/C. We also found that the maximum photo responsivity at 345 nm is 7.2 and 0.9 A/W when the detector is biased at 5 and 0.5 V, respectively.

Journal ArticleDOI
TL;DR: In this article, a waveguide avalanche photodiode with a record gain-bandwidth product of over 320 GHz has been demonstrated, achieving a bandwidth of 28 GHz at low gains with low excess noise and a quantum efficiency of 16% at 1.55 /spl mu/m.
Abstract: An In/sub 0.52/Al/sub 0.48/As-In/sub 0.53/Ga/sub 0.47/As waveguide avalanche photodiode with a record gain-bandwidth product of over 320 GHz has been demonstrated. A bandwidth of 28 GHz was achieved at low gains with low excess noise and a quantum efficiency of 16% at 1.55 /spl mu/m.

Journal ArticleDOI
Xuewen Shu1, Thomas D.P. Allsop, B.A.L. Gwandu1, Lin Zhang, Ian Bennion 
TL;DR: In this paper, thermal properties of long-period fiber gratings (LPFGs) of various periods fabricated in the conventional B-Ge codoped fiber have been investigated and a total of 27.5nm spectral shift was achieved from only 10/spl deg/C change in temperature for an LPFG with 240-/spl mu/m period.
Abstract: We report an investigation of thermal properties of long-period fiber gratings (LPFGs) of various periods fabricated in the conventional B-Ge codoped fiber. It has been found that the temperature sensitivity of the LPFGs produced in the B-Ge fiber can be significantly enhanced as compared with the standard telecom fiber. A total of 27.5-nm spectral shift was achieved from only 10/spl deg/C change in temperature for an LPFG with 240-/spl mu/m period, demonstrating a first ever reported high sensitivity of 2.75 nm//spl deg/C. Such an LPFG may lead to high-efficiency and low-cost thermal/electrical tunable loss filters or sensors with extremely high-temperature resolution. The nonlinear thermal response of the supersensitive LPG was also reported and first explained.

Journal ArticleDOI
Weigang Zhang1, Xiaoyi Dong, Qida Zhao, Guiyun Kai, Shuzhong Yuan 
TL;DR: An improved FBG-type sensor for simultaneous measurement of force and temperature based on the bilateral cantilever beam (BCB) is proposed and demonstrated in this paper, where two parts of the beam are subject to opposite forces (or displacements) leading to a red shift for the part of the FBG subject to stretch and to a blue shift for other one.
Abstract: An improved FBG-type sensor for simultaneous measurement of force (or displacement) and temperature based on the bilateral cantilever beam (BCB) is proposed and demonstrated. The two parts of the beam are subject to opposite forces (or displacements) leading to a red shift for the part of the FBG subject to stretch and to a blue shift for the other one. An FBG bonded to the surface of the middle of the BCB is experimentally demonstrated to have a force sensitivity of /spl sim/1.046 nm/N, a sensitivity of the displacement-based strain of /spl sim/0.317 nm/mm, and a temperature sensitivity of /spl sim/0.190 nm//spl deg/C between 0/spl deg/C and 70/spl deg/C, respectively.

Journal ArticleDOI
TL;DR: In this article, high-saturation power traveling-wave electroabsorption modulators (TW-EAMs) with modulation bandwidth greater than 40 GHz have been demonstrated and their properties were extracted from the measured S-parameters using an equivalent circuit model.
Abstract: High-saturation power traveling-wave electroabsorption modulators (TW-EAMs) with modulation bandwidth greater than 40 GHz have been demonstrated. Microwave properties of the TW-EAM waveguide are extracted from the measured S-parameters using an equivalent circuit model. Excellent agreement is obtained between the predicted and the measured frequency responses.

Journal ArticleDOI
TL;DR: This letter proposes and demonstrates a simple all-optical label detection and swapping technique incorporating a fiber Bragg grating (FBG) filter and a double sideband subcarrier multiplexed signal.
Abstract: This letter proposes and demonstrates a simple all-optical label detection and swapping technique incorporating a fiber Bragg grating (FBG) filter and a double sideband subcarrier multiplexed (DSB-SCM) signal. The optical datagram consisting of a baseband 2.488-Gb/s data payload and a subcarrier multiplexed 622-Mb/s label are optically processed to separate the two components, and then a new label content is encoded by subsequent optical modulation. The optically separated original label is detected by a square law detector without involving any high-frequency subcarrier circuitry. Bit-error-rate measurements confirm a successful and low-penalty label swapping technique, which maintains optical transparency for the data payload.

Journal ArticleDOI
TL;DR: In this article, Bragg gratings in polymethyl methacrylate (PMMA)-based polymer fibers were created and were tuned thermally, and it was found that the tuning range is more than 18 nm over a temperature variation of 50/spl deg/C.
Abstract: Bragg gratings in polymethyl methacrylate (PMMA)-based polymer fibers were created and were tuned thermally. It is found that the tuning range is more than 18 nm over a temperature variation of 50/spl deg/C. More importantly, no hysteresis effect was observed as the gratings were heated up and cooled down.

Journal ArticleDOI
TL;DR: In this paper, the authors present a transmitter setup for optical duobinary transmission with reduced complexity resulting from a simple precoder and from using a standard single-arm Mach-Zehnder modulator.
Abstract: We present a transmitter setup for optical duobinary transmission with reduced complexity resulting from a simple precoder and from using a standard single-arm Mach-Zehnder modulator. With this setup, data transmission at 10 Gb/s over a record length of 252-km uncompensated standard single-mode fiber (SSMF) is demonstrated.

Journal ArticleDOI
TL;DR: In this article, a hybrid ion implanted/selectively oxidized device structure was used to achieve high power single-mode operation of an 850-nm vertical-cavity laser under continuous-wave operation.
Abstract: Using a hybrid ion implanted/selectively oxidized device structure, we report high-power single-mode operation of an 850-nm vertical-cavity laser. Under continuous-wave operation, >4 mW of single-mode power with 45 dB of side-mode suppression is achieved. The spectral behavior under pulsed modulation is determined to be influenced by thermal lensing. When biased to threshold, single-mode operation with >35-dB side-mode suppression is obtained for large signal modulation.

Journal ArticleDOI
TL;DR: In this paper, the dependence of the measured ripple amplitude on the modulation frequency was analyzed and a physical model was presented to estimate the measurement error of the group delay in chirped fiber Bragg gratings.
Abstract: The phase-shift method is an established technique for measuring the group delay of fiber-optic components. In devices, such as chirped fiber Bragg gratings, the group delay exhibits ripple as a function of wavelength. We have analyzed the dependence of the measured ripple amplitude on the modulation frequency and present a physical model, which gives an analytical formula for estimating the measurement error.

Journal ArticleDOI
TL;DR: In this article, a symmetric-Mach-Zehnder-type all-optical polarization-insensitive semiconductor regenerator was used to achieve penalty-free data-pulse regeneration at 84 Gb/s.
Abstract: Penalty-free data-pulse regeneration at 84 Gb/s was achieved down to an error rate level of 1/spl times/10/sup -11/ by using a data pattern length of 2/sup 31/-1. A symmetric-Mach-Zehnder-type all-optical polarization-insensitive semiconductor regenerator was used.

Journal ArticleDOI
TL;DR: In this paper, a label swapping scheme based on logic exclusive-OR (XOR) in an integrated SOA-based Michelson interferometer is proposed, which allows simple, efficient and mechanically stable operation while relaxing the requirements on packet format and simplifying switch management.
Abstract: We present a novel scheme for all-optical label swapping that relies on logic exclusive-OR (XOR) in an integrated SOA-based Michelson interferometer. The scheme allows simple, efficient and mechanically stable operation, while relaxing the requirements on packet format and simplifying switch management. Furthermore, the label-swapping scheme does not require a guard band between the header and payload to perform alterations in the header. The method, which incorporates simultaneous wavelength conversion, is demonstrated at 10 Gb/s with negligible penalty and a high output signal-to-ASE ratio of /spl sim/35 dB.

Journal ArticleDOI
TL;DR: In this article, a method that utilizes a dispersion-shifted fiber having compound compositions with different temperature coefficients in core to simultaneously measure the distributed strain and temperature based on Brillouin frequency shift was proposed and realized.
Abstract: We propose and realize a new method that utilizes a dispersion-shifted fiber having compound compositions with different temperature coefficients in core to simultaneously measure the distributed strain and temperature based on Brillouin frequency shift. In a 3682-m sensing length of large-effective-area nonzero dispersion-shifted fiber, a temperature resolution of 5/spl deg/C, a strain resolution of 60 /spl mu//spl epsi/, and a spatial resolution of 2 m are achieved simultaneously.

Journal ArticleDOI
W. Ogaerts1, Peter Bienstman1, Dirk Taillaert1, Roel Baets1, D. De Zutter1 
TL;DR: In this article, the authors studied the out-of-plane scattering losses using a two-dimensional approximation of this three-dimensional structure, with etched slots instead of holes, and showed that the losses increase with higher index contrast, but that with very high index contrasts light can be coupled into lossless Bloch modes.
Abstract: Photonic crystal slabs combine a slab waveguide with an in-plane photonic crystal. Light is then confined in-plane by the photonic crystal and out-of-plane by the slab waveguide. The etched structures will cause light to scatter out of the waveguide plane. We studied the out-of-plane scattering losses using a two-dimensional approximation of this three-dimensional structure, with etched slots instead of holes. Our simulation techniques include mode expansion with perfectly matched layer absorbing boundary conditions. We show that the losses increase with higher index contrast, but that with very high-index contrasts light can be coupled into lossless Bloch modes.

Journal ArticleDOI
TL;DR: In this article, the optimal configuration of hybrid Raman/erbium-doped fiber amplifiers has been carried out yielding a closed form analysis, where the maximum reachable distance has been evaluated as a function of the span length and nonlinear weight.
Abstract: A comprehensive theoretical study on the optimal configuration of hybrid Raman/erbium-doped fiber amplifiers has been carried out yielding a closed form analysis. In order to compare different system configurations, a weight for the impact of fiber nonlinearities has been introduced. The maximum reachable distance has been evaluated as a function of the span length and nonlinear weight, given a target optical signal-to-noise ratio.

Journal ArticleDOI
TL;DR: Results show that fiber-based optical sampling is indeed a potential candidate for characterization of future ultrahigh bit-rate optical communication systems, and is comparable to previously reported state-of-the-art nonlinear crystal-based sampling systems.
Abstract: In this letter, we report on up to 300-Gb/s real-time all-fiber-based optical eye-diagram measurements with 1.6-ps temporal resolution and 5-Hz refresh rate by all-optical sampling using parametric amplification in a short (50 m) highly nonlinear fiber. This represents, to the best of our knowledge, the highest bit-rate eye-diagram measurement so far, as well as the first demonstration of a fiber-based eye analyzer. The sensitivity and operational optical bandwidth is comparable to previously reported state-of-the-art nonlinear crystal-based sampling systems. We believe our results show that fiber-based optical sampling is indeed a potential candidate for characterization of future ultrahigh bit-rate optical communication systems.

Journal ArticleDOI
TL;DR: In this article, photoluminescence (PL) and electroluminecence (EL) properties of InGaN-AlInGaN multiquantum-well (MQW) light-emitting diodes (LEDs) were evaluated and their optical properties were evaluated.
Abstract: InGaN-GaN and InGaN-AlInGaN multiquantum-well (MQW) light-emitting diodes (LEDs) were both fabricated and their optical properties were evaluated by photoluminescence (PL) as well as electroluminescence (EL). We found that the PL peak position of the InGaN-AlInGaN MQW occurs at a much lower wavelength than that of the InGaN-GaN MQW. The PL intensity of the InGaN-AlInGaN MQW was also found to be larger. The EL intensity of the InGaN-AlInGaN MQW LED was also found to be larger than that of the InGaN-GaN MQW LED under the same amount of injection current. Furthermore, it was found that EL spectrum of the InGaN-AlInGaN MQW LED is less sensitive to the injection current. These observations all suggest that we can improve the properties of nitride-based LEDs by using AlInGaN as the barrier layer.

Journal ArticleDOI
TL;DR: In this article, a new method for measuring the linewidth enhancement factor is presented based on the relation between the upper and lower bounds of the locked and unlocked regimes when the detuning of the pump and slave laser is plotted as a function of the injection power.
Abstract: A new method for measuring the linewidth enhancement factor is presented. This idea is based on the relation between the upper and lower bounds of the locked and unlocked regimes when the detuning of the pump and slave laser is plotted as a function of the injection power. Our results are confirmed with an independent measurement using amplified spontaneous emission (ASE) spectroscopy as well as our theory, which takes account of the realistic quantum-well (QW) band structure and many-body effects. This method provides a new approach to measure the linewidth enhancement factor above laser threshold.