Showing papers in "IEEE Photonics Technology Letters in 2006"
TL;DR: In this article, the authors compared the performances of optical millimeter-wave generation or up-conversion using external modulators based on different modulation schemes and found that the OCS modulation scheme has the highest receiver sensitivity, highest spectral efficiency and smallest power penalty over long-distance delivery.
Abstract: We have experimentally compared the performances of optical millimeter-wave generation or up-conversion using external modulators based on different modulation schemes. The generated or up-converted optical millimeter wave using the optical carrier suppression (OCS) modulation scheme shows the highest receiver sensitivity, highest spectral efficiency, and smallest power penalty over long-distance delivery. Moreover, the OCS modulation scheme has a simple configuration and low-frequency bandwidth requirement for both electrical and optical components. Employing an OCS modulation scheme, 16-channel dense wavelength-division multiplexing signals at 2.5-Gb/s per channel have been up-converted to a 40-GHz carrier simultaneously.
501 citations
TL;DR: In this paper, a Si photonic wire waveguide was incorporated into a Mach-Zehnder interferometer based sensor, configured to monitor the index change of a homogeneous solution.
Abstract: We demonstrate a new, highly sensitive evanescent field sensor using silicon-on-insulator (SOI) photonic wire waveguides Theoretical analysis shows that thin SOI waveguides can provide higher sensitivity over devices based in all other common planar waveguide material systems for the probing of both thin adsorbed biomolecular layers and bulk homogeneous solutions A Si photonic wire waveguide was incorporated into a Mach-Zehnder interferometer based sensor, configured to monitor the index change of a homogeneous solution High effective index change of 031 per refractive index unit (RIU) change of the solution was measured, confirming theoretical predictions
284 citations
TL;DR: In this paper, the use of a ~50mW peak power 4.3-THz quantum cascade laser (QCL) as an illumination source for real-time imaging with a 320 times 240 element room-temperature microbolometer focal-plane array detector is reported.
Abstract: We report the use of a ~50-mW peak power 4.3-THz quantum cascade laser (QCL) as an illumination source for real-time imaging with a 320 times 240 element room-temperature microbolometer focal-plane array detector. The QCL is modulated synchronously with the focal-plane array for differential imaging. Signal-to-noise ratios of ~340 are achieved at a 20-frame/s acquisition rate, and the optical noise equivalent power of the detector array at 4.3 THz is estimated to be ~320 pW/radicHz. Both reflection and transmission mode imaging are demonstrated
248 citations
Abstract: GaN-based light-emitting diodes (LEDs) with emitting wavelength of 450 nm were grown on patterned sapphire substrates (PSSs) fabricated by chemical wet etching The crystallography-etched facet was {1-102} R-plane with a 57deg against {0001} C-axis and had superior capability for enhancing light extraction efficiency The light output power of the PSS LED was 115 times higher than that of the conventional LED at an injection current of 20 mA The output power and external quantum efficiency were estimated to be 9 mW and 164%, respectively The improvement was attributed not only to geometrical shapes of {1-102} crystallography-etched facets that efficiently scatter the guided light to find escape cones, but also to dislocation density reduction by adopting the PSS growth scheme
233 citations
TL;DR: In this paper, a full-duplex radio-over-fiber system using a single light source at the central station (CS) was demonstrated, where the optical carrier suppression modulation scheme was employed to generate 40GHz optical millimeter wave and up-convert the baseband signal simultaneously at CS for downlink transmission while the same optical carrier was reused at base station for uplink connection.
Abstract: We have experimentally demonstrated a full-duplex radio-over-fiber system using a single light source at central station (CS). Optical carrier suppression modulation scheme was employed to generate 40-GHz optical millimeter wave and up-convert the baseband signal simultaneously at CS for downlink transmission while the same optical carrier was reused at base station for uplink connection. The bidirectional full-duplex 2.5-Gb/s data was successfully transmitted over 40-km standard single-mode fiber (SMF-28) for both upstream and downstream channels with less than 2-dB power penalty. This system shows simple cost-efficient configuration and good performance over long-distance delivery
231 citations
TL;DR: In this paper, a photonic phase shifter based on Brillouin signal processing of optical single-sideband signals is proposed, which provides broad operational bandwidth and a full 360/spl deg/ phase shift tuning range with a single external electrical control.
Abstract: We introduce a novel RF photonic phase shifter based on Brillouin signal processing of optical single-sideband signals. The theoretical fundamentals of the design are explained and the main factors influencing its performance are analyzed. This phase shifter provides broad operational bandwidth and a full 360/spl deg/ phase-shift tuning range with a single external electrical control. A prototype of the phase shifter with 18-GHz bandwidth and full 360/spl deg/ tuning range is experimentally demonstrated.
230 citations
TL;DR: In this article, a record optical fiber gain of 70 dB was obtained in a continuous-wave pumped fiber-optical parametric amplifier, where the spectral density of ASE was up to 180 mW/nm.
Abstract: A record optical fiber gain of 70 dB was obtained in a continuous-wave pumped fiber-optical parametric amplifier. Limitations due to saturation effects from amplified spontaneous emission (ASE) and due to stimulated Brillouin scattering in this unidirectional amplifier are discussed. The spectral density of ASE was up to 180 mW/nm in agreement with theoretical expectations, illustrating the possible use as a high brightness optical noise source
224 citations
TL;DR: In this paper, a novel photonic technique for microwave frequency measurement utilizing dispersion in a multichannel chirped fiber Bragg grating is presented based on the amplitude comparison of power fading functions generated by double sideband modulated optical carriers propagating through a dispersive medium.
Abstract: A novel photonic technique for microwave frequency measurement utilizing dispersion in a multichannel chirped fiber Bragg grating is presented. The technique is based on the amplitude comparison of power fading functions generated by double sideband modulated optical carriers propagating through a dispersive medium
217 citations
TL;DR: In this article, the optical phase modulation to intensity modulation conversion is achieved by reflecting the phase modulated light at the slopes of the fiber Bragg grating (FBG) that serves as a frequency discriminator.
Abstract: We propose a novel approach to generating ultrawideband impulse radio signals in the optical domain. The proposed system consists of a laser source, an electrooptic phase modulator (EOPM), a fiber Bragg grating (FBG), and a photodetector (PD). The light source is phase modulated by an electrical Gaussian pulse train via the EOPM. The optical phase modulation to intensity modulation conversion is achieved by reflecting the phase modulated light at the slopes of the FBG that serves as a frequency discriminator. Electrical monocycle or doublet pulses are obtained at the output of the PD by locating the wavelength of the optical carrier at the linear or the quadrature slopes of the FBG reflection spectrum. The use of the proposed configuration to implement pulse polarity and pulse shape modulation in the optical domain is discussed. Experimental measurements in both temporal and frequency domains are presented
211 citations
TL;DR: In this paper, a 10-Gb/s transmitter subsystem is described for single-mode fiber (G.652) single-input single-output (SISO) networks.
Abstract: We introduce digital precompensation for optical nonlinearities. A 10-Gb/s transmitter subsystem is described. Experimental results, across 320 and 1280 km of standard single-mode fiber (G.652) without any optical compensators, show substantial elimination of self-phase modulation. Some of the limits of this method are explored.
194 citations
TL;DR: In this paper, a white light-emitting diodes (WLEDs) were fabricated by combining blue InGaN chips with luminescent colloidal core-shell CdSe-ZnSe quantum dots (QDs).
Abstract: White light-emitting diodes (WLEDs) were fabricated by combining blue InGaN chips with luminescent colloidal core-shell CdSe-ZnSe quantum dots (QDs). The core-shell CdSe-ZnSe QDs synthesized by thermal deposition approach exhibited high photoluminescence efficiency with a quantum yield more than /spl sim/40%, and size-tunable emission wavelengths from 510 to 620 nm. Three-band red-green-blue WLED was successfully assembled by blue InGaN chips and green-emitting and red-emitting CdSe-ZnSe QDs. Based on QDs with flexibly selected color, the WLEDs exhibited white light with a CIE-1931 coordinate of (0.33, 0.33) and color rendering index R/sub a/ of 91.
TL;DR: A novel, simple, compact, and integrable scheme of reconfigurable and ultrafast photonic logic gate is demonstrated, based on a single semiconductor optical amplifier (SOA) and able to process ultrafast signals.
Abstract: A novel, simple, compact, and integrable scheme of reconfigurable and ultrafast photonic logic gate is demonstrated, based on a single semiconductor optical amplifier (SOA) and able to process ultrafast signals. XNOR function has been optically implemented exploiting four-wave mixing and cross-gain modulation in an SOA. The same scheme can be easily reconfigured to obtain AND, NOR, and NOT logic gates. Performances in terms of bit error rate for 20-ps return-to-zero signals at 10 Gb/s show a power penalty limited to 0.5 dB for all logic gates but the AND, which experiences regeneration (-2-dB power penalty) due to nonlinear SOA noise compression.
TL;DR: Experimental implementation of six logic functions (including XOR, XNOR, AND, NOR, etc.) operating at 10 Gb/s were realized by simply adjusting two polarization controllers in the setup.
Abstract: We have demonstrated simple reconfigurable all-optical logic operations based on four-wave mixing in semiconductor optical amplifier and encoding information in the polarization of the input signals. Experimental implementation of six logic functions (including XOR, XNOR, AND, NOR, etc.) operating at 10 Gb/s were realized by simply adjusting two polarization controllers in the setup
TL;DR: In this article, the authors present several simple sensitive fiber-optics-based sensors that utilize a biconical fiber taper, such as a displacement sensor with 100nm accuracy, a temperature monitor with sensitivity DeltaT 1.42times10-5, and a refractive-index sensor capable of measuring Deltan~1.42
Abstract: We present several simple sensitive fiber-optics-based sensors that utilize a biconical fiber taper. A displacement sensor with 100-nm accuracy, a temperature monitor with sensitivity DeltaT~1degC, and a refractive-index sensor capable of measuring Deltan~1.42times10-5 are demonstrated using tapers made from a standard single-mode fiber
TL;DR: In this article, the authors investigated theoretically and experimentally transmission color filters using silicon subwavelength gratings on quartz substrates, and obtained transmission spectrum obtained from a coupling between an incident light and the submicrometer periodic grating matches with human color perception.
Abstract: We investigate theoretically and experimentally transmission color filters using silicon subwavelength gratings on quartz substrates. Each grating area is 120 mum-square, which is suitable pixel size for displays and multichannel detectors. In the fabrication, electron beam lithography and fast atom beam etching are used. The grating periods are 400, 350, and 440 nm for the red, green, and blue filters, respectively. The transmission spectrum obtained from a coupling between an incident light and the submicrometer periodic grating matches with human color perception. The transmittances of 71.1%, 58.1%, and 59.3% are obtained for the red, green, and blue filters, respectively
TL;DR: In this paper, an all-fiber high-power single-frequency Brillouin fiber ring laser with maximum power of 100 mW at 1.55 mum was demonstrated, which was actively stabilized by using the Pound-Drever-Hall frequency-locking scheme.
Abstract: We demonstrate an all-fiber high-power single-frequency Brillouin fiber ring laser with maximum power of 100 mW at 1.55 mum, which is actively stabilized by using the Pound-Drever-Hall frequency-locking scheme. Significant reduction (~20dB) of both relative intensity noise and frequency noise was observed in the Brillouin Stokes radiation as compared with those noises of its pump source, a narrow-linewidth Er-doped fiber laser. Ultranarrow spectral linewidth of the Brillouin fiber lasers was investigated by both delayed self-heterodyne technique and heterodyne beat technique between two independent Brillouin fiber lasers
TL;DR: In this paper, a multimode-interference (MMI)-based crossing in high-index-contrast silicon wire waveguides is reported, which exhibits wavelength dependence of less than 2 dB within the 1520-1580-nm wavelength range.
Abstract: We report multimode-interference (MMI)-based crossings in high-index-contrast silicon wire waveguides Our experiments show an MMI crossing of ~04-dB insertion loss, which suggests ~09-dB improvement from a control plain crossing of the same size and refractive index contrast We also experimentally observe significant crosstalk suppression in our MMI crossing The MMI crossing transmission exhibits wavelength dependence of less than 02 dB within the 1520-1580-nm wavelength range
TL;DR: In this paper, a chirp-managed directly modulated laser (CML) was used for uncompensated 10-Gb/s transmission over >200 km at 1.55 /spl mu/m.
Abstract: We demonstrate a new highly dispersion tolerant modulation format using a chirp-managed directly modulated laser (CML) for uncompensated 10-Gb/s transmission over >200 km at 1.55 /spl mu/m. The CML consists of a distributed feedback (DFB) laser followed by an optical filter. We show that the combination of adiabatic chirp from the DFB and filter edge response produces high extinction ratio pulses with nearly uniform phase, abrupt phase shifts at bit transitions, and a correlation between the 1 bits; 1 bits separated by odd number of 0 bits are /spl pi/ out of phase. This results in carrier suppression, 1/2 the bandwidth of standard nonreturn-to-zero, and high tolerance to positive and negative dispersion.
TL;DR: In this article, a single longitudinal mode (SLM) dual-wavelength erbium-doped fiber (EDF) laser based on a simple linear cavity is proposed and demonstrated.
Abstract: A single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber (EDF) laser based on a simple linear cavity is proposed and demonstrated. The SLM operation is achieved by incorporating a dual-phase-shift fiber grating with two ultranarrow transmission bands. Due to the gain grating produced by spatial hole-burning in the EDF, the proposed linear cavity supports dual-wavelength oscillation at room temperature with a wavelength interval of 27 pm. The laser output is heterodyned on a photodetector and the generated microwave signal has a linewidth <20 kHz without any feedback.
TL;DR: In this paper, an optical interleaver was employed to separate the spectrum of the double-sideband signals generated by a single-arm intensity external modulator, and the separated first-order sideband modes were used to generate optical millimeter-wave with double RF frequency, while the separated optical carrier was reused for uplink connection.
Abstract: We proposed and experimentally demonstrated a novel scheme to generate an optical millimeter-wave and realized wavelength reuse for uplink connection in a radio-over-fiber system. We employed an optical interleaver to separate the spectrum of the double-sideband signals generated by a single-arm intensity external modulator. The separated first-order sideband modes were used to generate optical millimeter-wave with double RF frequency, while the separated optical carrier was reused for uplink connection
TL;DR: In this article, the authors demonstrate efficient wavelength conversion using a four-wave mixing effect in a silicon photonic wire waveguide with spot size converters, using a continuously operated 160-mW pump, power density in the waveguide's core was increased up to around 430 MW/cm/sup 2/
Abstract: We demonstrate efficient wavelength conversion using a four-wave-mixing (FWM) effect in a silicon photonic wire waveguide with spot size converters. Applying a continuously operated 160-mW pump, power density in the waveguide's core was increased up to around 430 MW/cm/sup 2/, and the FWM effect was remarkably enhanced. Internal conversion efficiency obtained in an experiment was -10.6 dB. The efficiency was significantly limited by the free-carrier absorption effect.
TL;DR: In this paper, the authors proposed a novel approach to generate and distribute ultrawideband (UWB) pulse signals over optical fiber, which consists of a single-wavelength laser source, an electrooptic phase modulator (EOPM), a length of single-mode fiber (SMF), and a photodetector (PD).
Abstract: We propose a novel approach to generating and distributing ultrawideband (UWB) pulse signals over optical fiber. The proposed system consists of a single-wavelength laser source, an electrooptic phase modulator (EOPM), a length of single-mode fiber (SMF), and a photodetector (PD). The combination of the EOPM, the SMF link, and the PD forms an all-optical microwave bandpass filter, which is used to generate a UWB signal with a spectrum meeting the regulation of the Federal Communication Commission. Gaussian doublet pulses are obtained at the receiver front-end, which can provide several gigahertz bandwidths for applications in high-bit-rate UWB wireless communications. Experimental results measured in both temporal and frequency domains are presented.
TL;DR: The hybrid silicon evanescent laser (SEL) as discussed by the authors utilizes offset AlGaInAs quantum wells (QWs) bonded to a silicon waveguide, which is fabricated on a silicon-on-insulator wafer using a complimentary metaloxide-semiconductor compatible process.
Abstract: We report a novel laser architecture, the hybrid silicon evanescent laser (SEL), that utilizes offset AlGaInAs quantum wells (QWs) bonded to a silicon waveguide. The silicon waveguide is fabricated on a silicon-on-insulator wafer using a complimentary metal-oxide-semiconductor-compatible process, and is subsequently bonded with the AlGaInAs QW structure using low temperature O2 plasma-assisted wafer bonding. The optical mode in the SEL is predominantly confined in the passive silicon waveguide and evanescently couples into the III-V active region providing optical gain. The SEL lases continuous wave (CW) at 1568 nm with a threshold of 23 mW. The maximum temperature for CW operation is 60degC. The maximum single-sided fiber-coupled CW output power at room temperature is 4.5 mW
TL;DR: In this paper, a commercial erbium-doped fiber laser is coupled into a standard silica fiber and a standard fluoride fiber connected in series, by cascaded Raman soliton self-shifting, a continuum extending to a wavelength of /spl sim/3 /spl mu/m is generated.
Abstract: Pulses from a commercial erbium-doped fiber laser are coupled into a standard silica fiber and a standard fluoride fiber connected in series. By cascaded Raman soliton self-shifting, a continuum extending to a wavelength of /spl sim/3 /spl mu/m is generated. The total average power emitted in the 1.8-3.4-/spl mu/m range is 5 mW. Throughout the 1.4-2.9-/spl mu/m range, the average spectral power is /spl sim/4 /spl mu/W/nm and higher, corresponding at 2.9 /spl mu/m to a spectral radiance approximately 4600 times that of a 3000 K blackbody.
TL;DR: In this paper, an optical phase modulator and an optical interleaver are used to suppress the optical carrier of the DWDM source, which is not as temperature sensitive as a fiber Bragg grating.
Abstract: We have proposed and experimentally demonstrated a novel scheme to generate a dense wavelength-division multiplexing (DWDM) optical millimeter-wave source by using an optical phase modulator and an optical interleaver. The stability of the DWDM optical millimeter wave generation is largely improved because we use an optical phase modulator without a dc-bias controller and an optical interleaver is subsequently employed to suppress the optical carrier of the DWDM source, which is not as temperature sensitive as a fiber Bragg grating. Moreover, the limitation of chromatic dispersion is greatly reduced due to avoiding the generation of higher order sidebands via driving the phase modulator with optimized RF signal
TL;DR: In this paper, the authors demonstrate a pulsed ytterbium-doped fiber master-oscillator power amplifier source at 1060 nm producing over 300 W of average power in 20-ps pulses at 1-GHz repetition rate.
Abstract: We demonstrate a pulsed ytterbium-doped fiber master-oscillator power amplifier source at 1060 nm producing over 300 W of average power in 20-ps pulses at 1-GHz repetition rate. The pulses generated by a gain-switched diode were compressed by a chirped fiber Bragg grating and amplified without any distortion with excellent spectral quality. This fiber master oscillator power amplifier system offers versatility and potential for further power scaling.
TL;DR: In this article, the sensing head is formed by a long-period fiber grating combined with a high-birefringence fiber loop mirror, resulting in a configuration capable of temperature and strain discrimination.
Abstract: This work presents an alternative solution for simultaneous measurement of strain and temperature. The sensing head is formed by a long-period fiber grating combined with a high-birefringence fiber loop mirror resulting in a configuration capable of temperature and strain discrimination. These optical devices have opposite sensitivity responses when a variation of temperature and/or strain is applied. Maximum errors of plusmn0.8degC and plusmn21muepsiv are reported over 60 degC and 700-muepsiv measurement ranges, respectively
TL;DR: In this paper, a hybrid wavelength division multiplexed/subcarrier multiple-xed passive optical network (WDM/SCM-PON) was proposed by using a reflective semiconductor optical amplifier (RSOA) as a modulator.
Abstract: A hybrid wavelength-division multiplexed/subcarrier multiplexed passive optical network (WDM/SCM-PON) which shares the same wavelength both up-link and down-link is presented by using a reflective semiconductor optical amplifier (RSOA) as a modulator. We investigated down-link of 622 Mb/s using distributed feedback laser diode with direct modulation and 100-Mb/s up-link using an RSOA as a modulator with 900-MHz SCM signal. In our scheme, a novel efficient and cost-effective WDM/SCM-PON using the same wavelength for down/up-link at each optical network unit is proposed and experimentally demonstrated
TL;DR: In this paper, the first experimental demonstration of 2D broadband reflectors is presented, which is based on the coupling of free space waves with two slow Bloch modes of the crystal.
Abstract: Two-dimensional (2-D) compact photonic crystal reflectors on suspended InP membranes were studied under normal incidence. We report the first experimental demonstration of 2-D broadband reflectors (experimental stopband superior to 200 nm, theoretical stopband of 350 nm). They are based on the coupling of free space waves with two slow Bloch modes of the crystal. Moreover, they present a very strong sensitivity of the polarization dependence, when modifying their geometry. A compact (50/spl times/50 /spl mu/m/sup 2/) demonstrator was realized and characterized, behaving either as a broadband reflector or as a broadband transmitter, depending on the polarization of the incident wave. Experimental results are in good agreement with numerical simulations.
TL;DR: In this article, an embedded fiber Bragg grating (FBG) sensor for simultaneous measurement of stress and temperature is proposed, where a uniform FBG is capsulated in a tapered polymer so that the grating is linearly chirped when the sensor is stressed.
Abstract: An embedded fiber Bragg grating (FBG) sensor for simultaneous measurement of stress and temperature is proposed, where a uniform FBG is capsulated in a tapered polymer so that the grating is linearly chirped when the sensor is stressed The value of applied stress and temperature can be obtained by measuring the chirp and central wavelength via a coefficient matrix Experimental results demonstrate that the sensor has a stress sensitivity of 262/spl times/10/sup -3/nm/N and a temperature sensitivity of 0108 nm//spl deg/C Since the FBG is well protected and no sudden strain change is imposed on it, the sensor is expected to have an excellent reliability