Showing papers in "IEEE Photonics Technology Letters in 1999"
Abstract: A design for a 100-nm bandwidth Raman amplifier is presented. The amplifier is pumped with eight, 130-mW lasers with wavelengths ranging from 1416 to 1502 nm. The peak-to-peak gain ripple is 1.1 dB. A new model was developed for this design that includes pump-to-pump and signal-to-signal interactions in addition to double Rayleigh scattering and amplified spontaneous emission. An understanding of the interactions among these various effects was essential to this design. These modeling results are based on measurements of the physical characteristics of the transmission fiber.
452 citations
TL;DR: In this paper, the authors report the spectral inversion and wavelength conversion using cascaded second-order nonlinearity in periodically poled LiNbO/sub 3/ waveguides pumped at 1.5 /spl mu/m.
Abstract: We report wavelength conversion and spectral inversion using cascaded second-order nonlinearity in periodically poled LiNbO/sub 3/ waveguides pumped at 1.5 /spl mu/m. The converter has an internal conversion efficiency of -8 dB, a conversion bandwidth of 76 nm, and a constant conversion efficiency for the 50-dB range of signal powers tested.
352 citations
TL;DR: The properties of photonic crystal fibers with large air holes can be modeled by a silica rod in air as mentioned in this paper, and it has been shown that the dispersion of such fibers could exceed -2000 ps/mm/km, or they could compensate (to within /spl plusmn/0.2%) the length of standard fiber over a 100nm range.
Abstract: The properties of photonic crystal fibers with large air holes can be modeled by a silica rod in air. Such approximate calculations show that the dispersion of photonic crystal fibers could exceed -2000 ps/mm/km, or they could compensate (to within /spl plusmn/0.2%) the dispersion of 35 times their length of standard fiber over a 100-nm range.
337 citations
TL;DR: In this paper, a glass microring resonator vertically coupled to a buried channel waveguide is investigated, achieving a ring radii of 10 /spl mu/m and channel drop bandwidth of 5 nm.
Abstract: Air-clad glass microring resonators vertically coupled to buried channel waveguides are experimentally investigated. Ring radii of 10 /spl mu/m, and channel drop bandwidths of 5 nm are reported. Vertical coupling eliminates the need for the etching of fine features, and relaxes the alignment of the resonator with respect to the input and output bus waveguides.
333 citations
TL;DR: In this article, an eight-channel add-drop cross-grid vertically coupled microring resonator (VCMRR) filter is proposed and demonstrated, which achieves a free-spectral range of 20 nm and optical bandwidth of 1 nm, while changes of the radii in increments of 50 nm lead to a nominal channel spacing of 5.7 nm.
Abstract: An eight-channel add-drop cross-grid vertically coupled microring resonator (VCMRR) filter is proposed and demonstrated. The cross grid comprises a grid-like array of buried channel waveguides which perpendicularly cross through each other, VCMRRs at each of the cross-grid nodes serve as the wavelength selective add-drop filters. Measured crosstalk levels at the crossings are typically less than -30 dB. Rings with a nominal radius of 10 /spl mu/m are used to achieve a free-spectral range of 20 nm and optical bandwidths of 1 nm, while changes of the radii in increments of 50 nm lead to a nominal channel spacing of 5.7 nm.
307 citations
TL;DR: In this article, the ground state gain is determined from cavity mode Fabry-Perot modulation for InAs quantum-dot laser emitting at 1.22 /spl mu/m.
Abstract: Amplified spontaneous emission measurements are investigated below threshold in InAs quantum-dot lasers emitting at 1.22 /spl mu/m. The dot layer of the laser was grown in a strained quantum well (QW) on a GaAs substrate. Ground state gain is determined from cavity mode Fabry-Perot modulation. As the injection current increases, the gain rises super-linearly while changes in the index of refraction decrease. Below the onset of gain saturation, the linewidth enhancement factor is as small as 0.1, which is significantly lower than that reported for QW lasers.
305 citations
TL;DR: In this article, a Bragg grating in a single-mode polymer optical fiber (POF) has been created, which has a length of 1 cm with a reflectivity of 80% and a linewidth of about 0.5 nm.
Abstract: A Bragg grating in a single-mode polymer optical fiber (POF) has been created. The novel grating has a length of 1 cm with a reflectivity of 80% and a linewidth of about 0.5 nm. The wavelength tunability of the POF grating by stretching was investigated and a wavelength tunable range of 20 nm has been achieved. Based on the properties of the polymer, we believe that this kind of grating has a wavelength tuning potential of more than 100 nm.
303 citations
TL;DR: In this paper, an integrated optical all-pass filter is presented that can be used for tunable dispersion compensation, dispersion slope compensation, and as building blocks in tunable bandpass filters.
Abstract: New integrated optical all-pass filters are presented that can be used for tunable dispersion compensation, dispersion slope compensation, and as building blocks in tunable bandpass filters. The dispersion slope compensation capability is demonstrated using ring resonators in /spl Delta/=2% Ge-doped silica planar waveguides. In addition, a tunable four-stage filter with free-spectral range (FSR)=25 GHz, a passband width of 14 GHz (0.56/spl times/FSR), and D=1800 ps/nm is reported.
237 citations
TL;DR: In this article, the optical characteristics of the first laser diodes fabricated from a single-InAs quantum-dot layer placed inside a strained InGaAs QW are described, and the saturated modal gain for this novel laser active region is found to be 9-10 cm/sup -1/ in the ground state.
Abstract: The optical characteristics of the first laser diodes fabricated from a single-InAs quantum-dot layer placed inside a strained InGaAs QW are described. The saturated modal gain for this novel laser active region is found to be 9-10 cm/sup -1/ in the ground state. Room temperature threshold current densities as low as 83 A/cm/sup 2/ for uncoated 1.24-/spl mu/m devices are measured, and operating wavelengths over a 190-nm span are demonstrated.
233 citations
TL;DR: In this paper, a Muller matrices-based measurement technique was proposed for the determination of second-and higher-order PMD vectors in optical fibers, which requires the launch of only two polarizations per wavelength and uses large rotation angles as well as interleaving.
Abstract: A polarization-mode dispersion (PMD) measurement technique is described that allows the determination of second- and higher order PMD vectors in optical fibers. The algorithm, based on Muller matrices, requires the launch of only two polarizations per wavelength and uses large rotation angles as well as interleaving to attain low-noise high-resolution PMD data. It has been applied to fibers ranging from 2 to 40 ps in mean PMD.
217 citations
TL;DR: In this paper, the authors proposed a system of wavelength-tunable femtosecond (fs) fundamental soliton pulse generation with a monocolored soliton, not multicolored ones, with the ideal sech/sup 2/shape.
Abstract: Using passively mode-locked femtosecond (fs) fiber laser and polarization maintaining fibers, the compact system of wavelength-tunable femtosecond (fs) fundamental soliton pulse generation is realized. The monocolored soliton pulse, not multicolored ones, with the ideal sech/sup 2/ shape is generated, and its wavelength can be linearly shifted by varying merely the fiber-input power in the wide wavelength region of 1.56-1.78 /spl mu/m for a 75-m fiber. The soliton pulses of less than 200 fs are generated with the high conversion efficiency of 75%-85%. This system can be widely used as a portable and practical wavelength-tunable fs optical pulse sources.
TL;DR: In this article, the first widely tunable semiconductor laser with an integrated electroabsorption modulator is reported, which is capable of producing more than 22 dB of optical extinction over the entire tuning range of the laser with a -40-V bias.
Abstract: We report on the development of the first widely tunable semiconductor laser with an integrated electroabsorption modulator The laser is a four-section buried-ridge sampled-grating distributed Bragg reflector design It has a 41-nm continuous tuning range with a maximum tuning current of 235 mA for the hack mirror and 21 mA for the front mirror The modulator is based on a 087-eV bandgap bulk waveguide structure It is capable of producing more than 22 dB of optical extinction over the entire tuning range of the laser with a -40-V bias
TL;DR: In this article, a variable optical attenuator for single mode fibers is described, which operates by moving an obstructing element in the optical beam in order to adjust the light damping.
Abstract: In this letter, we describe a variable optical attenuator for single mode fibers. As for its counterparts based on conventional mechanics the micromechanical attenuator operates by moving an obstructing element in the optical beam in order to adjust the light damping. The device is fabricated using the silicon micromachining technology. This allows one to integrate the electrostatic actuator together with the fiber alignment grooves and the obstructing element. With this design, an insertion loss below 1.5 dB was achieved. The response time was below 5 ms and no hysteresis was measured. The maximum attenuation was -57 dB. Backreflection attenuation was below -37 dB.
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TL;DR: A photonic Internet protocol (IP) routing is proposed in which the IP address, mapped onto optical code, is recognized by performing optical correlation in the time domain in a parallel manner to overcome the bottleneck in current electrical IP routers.
Abstract: A photonic Internet protocol (IP) routing is proposed in which the IP address, mapped onto optical code, is recognized by performing optical correlation in the time domain in a parallel manner. Preliminary experiment shows that it can process 6.5/spl times/10/sup 9/ packets per second. It will help overcome the bottleneck in current electrical IP routers; i.e., the time it takes to look up addresses in the routing table.
TL;DR: In this article, the authors compare nonreturn-to-zero (NRZ) with return-tozero (RZ) modulation format for wavelength-division-multiplexed systems operating at data rates up to 40 Gb/s.
Abstract: We compare nonreturn-to-zero (NRZ) with return-to-zero (RZ) modulation format for wavelength-division-multiplexed systems operating at data rates up to 40 Gb/s. We find that in 10-40-Gb/s dispersion-managed systems (single-mode fiber alternating with dispersion compensating fiber), NRZ is more adversely affected by nonlinearities, whereas RZ is more affected by dispersion. In this dispersion map, 10- and 20-Gb/s systems operate better using RZ modulation format because nonlinearity dominates. However, 40-Gb/s systems favor the usage of NRZ because dispersion becomes the key limiting factor at 40 Gb/s.
Abstract: Transverse mode selection has been introduced in a large area oxide-confined vertical-cavity surface-emitting laser (VCSEL) by etching a shallow (only 40-nm deep) surface relief. The circular relief pattern, intended for fundamental mode selection, selects low order modes, resulting in significantly reduced beam divergence (from 48/spl deg/ to 13/spl deg/ and less over the entire drive current range) and improved spectral purity (width of emission spectrum reduced from 5 to less than 0.3 nm) compared to VCSEL's without surface relief. A maximum output power of 10 mW was measured.
TL;DR: In this paper, an all-optical passive four-port system including a fused silica microsphere and two tapered fibers is proposed and demonstrated for the application as a channel adding-dropping device.
Abstract: An all-optical passive four-port system including a fused silica microsphere and two tapered fibers is proposed and demonstrated for the application as a channel adding-dropping device. It is shown that channels can be selectively exchanged between two fibers by coupling to a whispering gallery mode resonance in the microsphere. Finesse in excess of 11150 is measured for the loaded whispering gallery modes.
TL;DR: In this article, a fiber grating-based sensor with a fiber-grating Fabry-Perot cavity (GFPC) structure was fabricated and tested for simultaneous measurement of strain and temperature.
Abstract: A novel and short (5 mm long) fiber grating based sensor with a fiber grating Fabry-Perot cavity (GFPC) structure was fabricated and tested for simultaneous measurement of strain and temperature. The sensor exhibits unique properties that it possesses two spectral peaks within its main reflection band and the normalized peak power difference, in addition to its peak wavelength shift, changes linearly with strain or temperature. The accuracy of this particular sensor in measuring strain and temperature are estimated to be /spl plusmn/30 /spl mu/s in a range from 0 to 3000 /spl mu/s and /spl plusmn/0.4/spl deg/C from 20/spl deg/C to 60/spl deg/C, respectively.
TL;DR: In this paper, the first 1.3/spl mu/m continuous-wave (CW) lasing at room temperature of self-assembled InGaAs-GaAs quantum dots was demonstrated.
Abstract: We demonstrate the first 1.3-/spl mu/m continuous-wave (CW) lasing at room temperature of self-assembled InGaAs-GaAs quantum dots. High-density 1.3-/spl mu/m emission dots were successfully formed by the combination of low-rate growth and InGaAs-layer overgrowth methods of molecular beam epitaxy. The 1.3-/spl mu/m ground-level CW lasing occurred at up to 40/spl deg/C, and the threshold current of 8 mA at 25/spl deg/C is less than one thirtieth of values ever reported for 1.3-/spl mu/m dot pulse lasers. The achievement represents a milestone for creating quantum-dot lasers applicable to fiber-optic communication system.
TL;DR: In this paper, a tunable dispersion compensating fiber Bragg grating (FBG) device is presented, which relies on a distributed on-fiber thin-film heater deposited onto the outer surface of an unchirped FBG.
Abstract: Novel devices only offer reasonable telecommunication solutions when they can be packaged and manufactured efficiently and at low cost. We demonstrate such a compact and power efficient tunable dispersion compensating fiber Bragg grating (FBG) device. The device relies on a distributed on-fiber thin-film heater deposited onto the outer surface of an unchirped FBG. Current flowing though the thin film generates resistive heating that is governed by the thickness profile of the metal film. A chirp in the grating is obtained by using a coating whose thickness varies with position along the length of the grating in a prescribed manner; the chirp rate is adjusted by varying the applied current. Using an electrical power of less than 1 W in a packaged device, we demonstrate a linearly chirped Bragg grating in which the dispersion is continuously tuned from -300 to -1350 ps/nm, with an average deviation from linearity of approximately 10 ps.
TL;DR: In this paper, a high-speed, resonant-cavity InGaAs-InAlAs separate absorption, charge, and multiplication avalanche photodiode (APD) operating at a wavelength of 1.55 /spl mu/m.
Abstract: We demonstrated a high-speed, resonant-cavity InGaAs-InAlAs separate absorption, charge, and multiplication avalanche photodiode (APD) operating at a wavelength of 1.55 /spl mu/m. Due to the resonant-cavity scheme, these APDs exhibit high external quantum efficiency (/spl sim/70%) and a high unity-gain bandwidth of 24 GHz. Utilizing the excellent noise characteristics of a thin InAlAs multiplication region (k/spl sim/0.18), we have also achieved a gain-bandwidth product of 290 GHz. These bandwidth results are believed to be the highest reported values for APDs operating at 1.55 /spl mu/m.
TL;DR: In this paper, the authors report the first demonstration of all-optical label swapping with wavelength conversion and subcarrier multiplexed addressing for WDR IP, which utilizes a module which is based on cascaded semiconductor optical amplifier wavelength converters that perform the functions of label removal, label rewriting, payload 2R regeneration and double sideband sub-carrier label regeneration.
Abstract: We report the first demonstration of all-optical label swapping with wavelength conversion and subcarrier multiplexed addressing for WDR IP. This demonstration utilizes a module which is based on cascaded semiconductor optical amplifier wavelength converters that perform the functions of label removal, label rewriting, payload 2R regeneration and double sideband subcarrier label regeneration. Replacement of double-sideband subcarrier labels on a hop-by-hop basis addresses the problem of dispersion induced fading in a multihop fiber network. A direct detection subcarrier receiver is used to recover the label. Switching over four wavelengths covering 16 nn is demonstrated with noninverting wavelength conversion of 2.5-Gb/s payloads and burst mode recovery of 10-Mb/s labels. BER measurements of better than 10/sup -9/ for the wavelength-converted payload and rewritten labels at all wavelengths are presented.
TL;DR: In this article, a new fiber Bragg grating sensor configuration is presented for simultaneous measurement of strain and temperature in germanosilicate fibers. But the sensor is not suitable for applications in smart structures and composite materials.
Abstract: A new fiber Bragg grating sensor configuration is presented for simultaneous measurement of strain and temperature. The sensor utilizes the effect of boron codoping on the temperature dependence of the refractive index in germanosilicate fibers. By writing gratings with dose wavelengths in undoped acid boron doped fibers, different temperature sensitivities are obtained while strain sensitivities remain the same. These gratings are then spliced to obtain a simple sensor head suitable for applications in smart structures and composite materials.
TL;DR: In this paper, the variation of the birefringence with input polarization and input power is measured, and an optical control of the BIR can be applied to wavelength conversion, signal regeneration, all-optical switching or gating.
Abstract: The polarization sensitivity of semiconductor optical amplifiers can be assessed in terms of gain or in terms of induced phase shift. Although the former aspect has received a lot of attention, the latter is rarely mentioned in the literature. Nevertheless, this birefringence leading to a rotation of the lightwave polarization at the output of the device may give rise to some interesting or unwanted effects. An optical control of the birefringence can be applied to wavelength conversion, signal regeneration, all-optical switching or gating. In this letter, the variation of the birefringence with input polarization and input power is measured.
TL;DR: In this article, the authors demonstrate the sampling of microwave signals using a novel time and wavelength-interleaved pulse train derived from a mode-locked fiber laser for use in a hybrid photonic analog-digital converter architecture.
Abstract: We experimentally demonstrate the sampling of microwave signals using a novel time- and wavelength-interleaved pulse train derived from a mode-locked fiber laser. Experimental results are presented indicating a modulator limited bandwidth of 18 GHz and a laser relative intensity noise limited effective number of bits of /spl sim/7 when tested for use in a hybrid photonic analog-digital converter architecture.
TL;DR: In this paper, a new approach in the design of (Al)InGaAsSb-GaSb quantum-well separate confinement heterostructure (QW-SCH) diode lasers has led to continuous-wave (CW) room-temperature lasing up to 2.7 /spl mu/m.
Abstract: A new approach in the design of (Al)InGaAsSb-GaSb quantum-well separate confinement heterostructure (QW-SCH) diode lasers has led to continuous-wave (CW) room-temperature lasing up to 2.7 /spl mu/m. This has been achieved by using quasiternary heavily strained InGaSb(As) QW's inside a broad-waveguide SCH laser structure. The QW compositions are chosen in the region outside the miscibility gap and, as a consequence, do not suffer from clustering and composition inhomogeneity normally found with quaternary InGaAsSb compounds of 2.3-2.7-/spl mu/m spectral range. Very low threshold current density (/spl sim/300 A/cm/sup 2/) and high CW output powers (>100 mW) were obtained from devices operating in the 2.3-2.6-/spl mu/m wavelength range.
TL;DR: In this article, the phase relationship between the rings determines the details of the spectral response, and the rings used in the experiment have radii of 25 /spl mu/m and are fabricated from compound glass having an index of 1.539.
Abstract: Ring resonators are coupled in parallel in order to obtain a second order type of wavelength response. The phase relationship between the rings determines the details of the spectral response. The rings used in the experiment have radii of 25 /spl mu/m and are fabricated from compound glass having an index of 1.539. Several resonances are observed to have double peaked box-like response.
TL;DR: In this article, a novel structure which utilizes detrimental backward amplified spontaneous emission as a secondary pump source is suggested for a silica-based fiber amplifier, operating at a wavelength range from 1570 to 1610 nm.
Abstract: A novel structure, which utilizes detrimental backward amplified spontaneous emission as a secondary pump source is suggested for a silica-based fiber amplifier, operating at a wavelength range from 1570 to 1610 nm. By using the secondary pumping effect from the strong, wasted 1550-nm band amplified spontaneous emission power in the unpumped section of the erbium-doped fiber, it was possible to achieve a considerable improvement in power conversion efficiency, increasing small-signal gain by more than 4 dB. The suggested pump structure was also shown to be useful in overall conversion efficiency improvement for L-band EDFA's, regardless of pump wavelength choice.
TL;DR: In this article, the first integration of vertical-cavity surface-emitting laser arrays with gigabit-per-second CMOS circuits via flip-chip bonding is described.
Abstract: We describe the first integration of vertical-cavity surface-emitting laser arrays with gigabit-per-second CMOS circuits via flip-chip bonding.
TL;DR: In this article, a wideband and finely gain-flattened hybrid fiber amplifier is realized, which consists of an erbium-doped fiber amplifier, a discrete Raman amplifier, which has two isolated Raman fibers pumped simultaneously at three wavelengths, and a small peak-loss gain equalizer.
Abstract: A wide-band and finely gain-flattened hybrid fiber amplifier is realized. The seamless 3.0-, 1.3-, and 1.0-dB bandwidths of 80, 76, and 69 nm with relative gain-flatness of 11.3%, 4.7%, and 3.7%, respectively, are achieved for the first time using the amplifier. The amplifier consists of an erbium-doped fiber amplifier, which has a short fluoride-based erbium-doped fiber, a discrete Raman amplifier, which has two isolated Raman fibers pumped simultaneously at three wavelengths, and a small-peak-loss gain-equalizer. The amplifier also yields optical noise figures under 6.0 dB.