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Lightwave Technology, Journal of

Issue 7 • Date Jul 1996

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Displaying Results 1 - 21 of 21
  • A TM Y-branch wavelength multi/demultiplexer by K+ and Ag+ ion-exchange for λ=1.31 and 1.55 μm

    Publication Year: 1996 , Page(s): 1690 - 1694
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    A Y-branch multi/demultiplexer by K+ and Ag+ ion-exchange was optimally designed, using the 2-D beam propagation method (BPM) and successfully fabricated for λ=1.31 and 1.55 μm. The measured extinction ratios of our preliminary devices are about 20 dB View full abstract»

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  • Optimization of wavelength tuning of erbium-doped fiber ring lasers

    Publication Year: 1996 , Page(s): 1730 - 1739
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (912 KB)  

    The dynamics of erbium-doped fiber ring lasers undergoing wavelength tuning is examined. The relaxation oscillations and mode build-up time are characterized. An all-optical damping technique which is capable of complete elimination of relaxation oscillations is analyzed, and measurements on a tunable erbium-doped fiber lasers are reported. An analytical solution is derived for the mode build-up time of tunable fiber lasers. Limiting parameters for the design of a high-speed tunable fiber laser are identified. An equalization technique for obtaining uniform switching speed is described View full abstract»

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  • Multiplexed optical fiber sensors using a single Fabry-Perot resonator for phase modulation

    Publication Year: 1996 , Page(s): 1653 - 1663
    Cited by:  Papers (6)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (908 KB)  

    This paper describes the use of different optical return paths in a single Fabry-Perot phase modulator to perform coherence division multiplexing, and a combination of coherence and frequency division multiplexing of Fabry-Perot interferometric optical fiber sensors. A path-matched differential interferometry (PMDI) using low finesse Fabry-Perot sensors, one moderate finesse Fabry-Perot read-out resonator, and a broadband light source consisting of amplified spontaneous emission (ASE) from an erbium-doped fiber amplifier (EDFA) is used to illustrate the idea. The first, second and third order of multiple paths in a single Fabry-Perot read-out resonator are used to path-match three Fabry-Perot sensors. These three orders of path-matches provide a single, double and triple depth of modulation (phase-change) when the read-out is used as an optical phase modulator, and therefore provide a single, double and triple carrier frequency when serrodyne demodulation is used. The use of a single moderate finesse read-out Fabry-Perot resonator to simultaneously path-match coherence multiplexed sensors reduces the complexity of the optical system. Experiments and modeling are used to show the existence of the first, second, and third order of interference path-match conditions, and to determine the read-out configuration that enhances the visibility of the higher order path-match conditions. Using the multiple return paths in a single PZT-based Fabry-Perot read-out interferometer and serrodyne demodulation, several multiplexing schemes are investigated, and their relative merits discussed View full abstract»

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  • A novel transmitter/receiver switching circuit configuration for high-performance LD transceiver in subscriber loop

    Publication Year: 1996 , Page(s): 1644 - 1652
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1012 KB)  

    LD (laser diode) transceivers are very effective in reducing optical subscriber systems cost because they act as transmitters and receivers. This paper proposes a new transceiver switching circuit configuration, and two techniques for suppressing and canceling the discharge current effect of laser diodes. The new techniques, including mounting substrate optimization such as high-isolation and low parasitic capacitance, yield a high-performance LD transceiver module with the minimum average receiving optical power level of -37.0 dBm and a wide dynamic range of up to 25 dB for burst mode optical input at 29.0 Mb/s View full abstract»

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  • Crosstalk reduction in intersecting rib waveguides

    Publication Year: 1996 , Page(s): 1695 - 1698
    Cited by:  Papers (13)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    A numerical study of the throughput and crosstalk in intersecting semiconductor rib waveguides was carried out using the beam propagation method. The fraction of the optical power that couples out of one input waveguide and into the crossed waveguide falls to below two percent for crossing angles greater than four degrees. A simple modification to the waveguide shape at the X-crossing region was found to reduce the crosstalk for crossing angles between four and ten degrees. The crosstalk to throughput ratio is reduced by up to a factor of nine while the throughput is reduced by, at most, a few percent. In device structures that combine X-crossings with curved waveguide sections this permits greater design flexibility and improved overall loss and crosstalk performance View full abstract»

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  • High-isolation demultiplexing in bend-tuned twin-core fiber

    Publication Year: 1996 , Page(s): 1740 - 1745
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    By applying a cantilever bend to a twin-core optical fiber wavelength division demultiplexer, isolations of >30 dB have been achieved between channels at 1.33-1.54 μm. These bend-tuned TCF's exhibit ⩾20 dB isolation over a bandwidth of 32 and 21 nm in the two wavelength windows, respectively. This is significantly better than that typically offered by commercially available, single-stage, tapered coupler demultiplexers. The bend-tuning mechanism is demonstrated experimentally and described theoretically using a coupled local-mode analysis View full abstract»

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  • Lossless stripe waveguide optical beam splitter: modeling of the Y-structure

    Publication Year: 1996 , Page(s): 1699 - 1703
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    We present a theoretical model of a loss-compensated symmetric Y-junction acting as an optical beam splitter. We consider silica (SiO 2) channel waveguides which are assumed to be highly doped with Er3+. The model was developed using the beam propagation method (BPM) and a fast-Fourier-transform (FFT)-based algorithm. The analysis showed that considerable gain levels, about 4.2 dB/cm at each port of the Y-junction, can be achieved for erbium concentration 2.5×1020 ions/cm3, signal power 1 μW and pump power 250 mW View full abstract»

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  • Dynamic scheduling protocol for variable-sized messages in a WDM-based local network

    Publication Year: 1996 , Page(s): 1595 - 1600
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    In a single-hop star network based on wavelength division multiplexing (WDM), a protocol is needed for the transmitter and receiver to coordinate message transmission. This paper proposes a dynamic scheduling protocol which can efficiently support variable-sized messages, where a control channel is used to coordinate transmissions on data channels. The protocol does not require any global information. Therefore, it can operate independently of the change of the number of nodes, and any new node can join the network at any time without requiring network initialization. Moreover, with the protocol, one can avoid data channel and destination conflicts. The protocol is analyzed with a finite population model and the throughput-delay characteristics are investigated as performance measures View full abstract»

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  • Optical low coherence method for characterizing silica-based arrayed-waveguide grating multiplexers

    Publication Year: 1996 , Page(s): 1677 - 1689
    Cited by:  Papers (43)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1312 KB)  

    We describe a powerful method for the precise measurement of optical path phase errors and power-distribution coefficients in silica-based arrayed-waveguide grating multiplexers through the use of Fourier transform spectroscopy. The theoretical accuracies for measuring these parameters are ±1° and ±5%, respectively, when the geometrical step increment of the arrayed waveguides is greater than 48 μm. The method reveals the random distributions of optical path phase errors in two multiplexers with channel spacings of 100 and 10 GHz, and proves that these distributions are the main origins of the channel crosstalk. The method predicts that when optical path phase errors are sufficiently reduced, the channel crosstalk values will decrease to -39 and -29 dB, respectively, and these limits are due to slightly deformed power distributions View full abstract»

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  • Cycles in wavelength routed optical networks

    Publication Year: 1996 , Page(s): 1585 - 1594
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    Signals in wavelength routed optical networks can oscillate in closed cycles resulting in adverse effects on network operation. In particular, amplified spontaneous emission from erbium doped fiber amplifiers can form recirculating loops that lead to amplifier saturation and oscillations. Searching, enumerating and eliminating these closed cycles becomes a problem that the network designer must address. A variety of cross-connect technologies are studied and shown to result in oscillating cycles in the network. Topological and technological approaches based on Eulerian network theory and other methods are proposed to eliminate these cycle problems View full abstract»

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  • Energy transfers and frequency shifts from three soliton collisions in a multiplexed transmission line with periodic amplification

    Publication Year: 1996 , Page(s): 1639 - 1643
    Cited by:  Papers (11)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    In this paper, we show that there can be four wave mixing between three solitons having different, but equally spaced, frequencies. While this does not happen with solitons in a uniform lossless fiber, we show that in a transmission line with loss and periodically placed amplifiers, it can happen. The spatial periodicity of the transmission line serves to phase match the four wave mixing of the three solitons. This results in permanent frequency shifts for two of the three solitons and energy exchanges between all three solitons View full abstract»

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  • Pulse shape evolution and noise estimates in concatenated fiber links using analog optoelectronical repeaters

    Publication Year: 1996 , Page(s): 1621 - 1629
    Cited by:  Papers (7)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB)  

    The pulse shape evolution in a chain consisting of dispersive fiber segments concatenated by analog optoelectronical repeaters is investigated. Analytical results based on a linear propagation model and Gaussian pulse shape with linear chirp as well as more realistic simulations, taking into account different pulse shapes and fiber nonlinearities, show that analog optoelectronical repeaters allow a significant improvement in the dispersion accumulation along the chain compared with all-optical amplification. To transmit data sequences, return-to-zero modulation has to be applied and simulations show that 10 Gb/s data can be transmitted at least over a distance of 1000 km with an power penalty caused by dispersion of 0.7 dB only. However, the noise accumulation reduces this length. For sufficiently large number of fiber segments with realistic parameters, the all-optical amplification performs better from a noise point of view View full abstract»

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  • Design and characterization of a mode-splitting Ψ-junction

    Publication Year: 1996 , Page(s): 1746 - 1752
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (644 KB)  

    It will he shown In this paper, that the mode conversion factor (MCF) as defined for Y-junctions, can be profitably applied for the design of three branch junctions for splitting the three lowest-order modes of a channel waveguide. Accordingly, these so-called mode-splitting Ψ-junctions were designed for implementation in PECVD SiON-technology. Propagation calculations point to crosstalk levels well below -20 dB at 10-20 mm junction length. The produced Ψ-junctions show crosstalk of less than -17 dB, mainly originating from the nonhomogeneity of the refractive indexes of the SiON layers View full abstract»

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  • Temperature and modulation characteristics of resonant-cavity light-emitting diodes

    Publication Year: 1996 , Page(s): 1721 - 1729
    Cited by:  Papers (74)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (888 KB)  

    Resonant-cavity light-emitting diodes (RCLED) are novel, high-efficiency light-emitting diodes which employ optical microcavities. These diodes have higher intensities and higher spectral purity as compared to conventional LEDs. Analytical formulas are derived for the enhancement of the spontaneous emission along the optical axis of the cavity. The design rules for high-efficiency operation of RCLEDs are established. The temperature dependence of the emission intensity is analyzed in the range 20-80° and it is described by an exponential dependence with a characteristic temperature of 112 K. The modulation characteristics of RCLEDs exhibit 3 dB frequencies of 580 MHz. Eye diagrams at transmission rates of 622 Mb/s are wide open indicating the suitability of RCLEDs for high-speed data transmission View full abstract»

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  • Partitioned optical passive star (POPS) multiprocessor interconnection networks with distributed control

    Publication Year: 1996 , Page(s): 1601 - 1612
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1156 KB)  

    This paper presents a partitioned optical passive star (POPS) interconnection topology and a control methodology that, together, provide the high throughput and low latency required for tightly coupled multiprocessor interconnection applications. The POPS topology has constant and symmetric optical coupler fanout and only one coupler between any two nodes of the network. Distributed control is based on the state sequence routing paradigm which multiplexes the network between a small set of control states and defines control operations to be transformations of those states. These networks have highly scalable characteristics for optical power budget, resource count, and message latency. Optical power is uniformly distributed and the size of the system is not directly limited by the power budget. Resource complexity grows as O(n) for the couplers, O(n√n) for transceivers, and O[√nlog(n)] for control. We present analysis and simulation studies which demonstrate the ability of a POPS network to support large scale parallel processing (1024 nodes) using current device and coupler technology View full abstract»

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  • Multiwavelength cross-connects for optical transport networks

    Publication Year: 1996 , Page(s): 1613 - 1620
    Cited by:  Papers (19)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (816 KB)  

    Multiwavelength cross-connects (M-XCs) will play a key role in future optical multiwavelength transport networks. In this paper, we propose a class of optical wavelength interchange devices that can be used as basic building-blocks for multiwavelength optical cross-connects. We describe three different multiwavelength cross-connect structures that can be constructed using these building blocks. We investigate their blocking performance and examine issues such as complexity, modularity, and wavelength channel spacing associated with the proposed cross-connect structures View full abstract»

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  • Optical spot-size converters for low-loss coupling between fibers and optoelectronic semiconductor devices

    Publication Year: 1996 , Page(s): 1714 - 1720
    Cited by:  Papers (19)  |  Patents (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    Structures of spot size converters that allow low loss and easy coupling between an optical semiconductor device and a fiber are proposed and designed theoretically. These spot-size converters have a tapered small core for expanding the mode field. They also have a double cladding region which consists of an n+-doped InP substrate as the outer cladding and a p-doped or nondoped InP layer as the inner cladding with a ridge structure. This double cladding utilizes the plasma effect of a carrier which makes the refractive index of highly doped n-InP lower than that of p-doped or nondoped InP. The double-cladding structure can tightly confine an expanded mode field in the inner cladding, and results in low radiation loss at the tapered waveguide, in addition, this structure reforms the mode field shape into a Gaussian-like shape and achieves a low loss coupling of less than 1 dB with a large misalignment tolerance for fiber coupling. These spot-size converters are easily fabricated and applicable to all types of optical semiconductor devices View full abstract»

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  • Laser-fabricated low-loss single-mode raised-rib waveguiding devices in polymers

    Publication Year: 1996 , Page(s): 1704 - 1713
    Cited by:  Papers (60)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1504 KB)  

    Organic polymeric materials offer a versatile medium for the creation of low-cost large-area optical guided-wave structures. In this work, we report on the use of a novel maskless laser-based microfabrication technique for the photochemical delineation of raised-rib single-mode waveguiding devices in polymers. This technology relies on accurate control of small refractive index differences (which is achieved by using intermiscible acrylate monomers), use of high-contrast photochemical response, as well as precise control of laser writing parameters. The devices reported here have cross-sectional dimensions and numerical apertures that match single-mode glass optical fibers. They exhibit very low losses of 0.03 dB/cm at 840 nm and exceptional thermal stability. We present the operational characteristics of bends, Y-branches, and directional couplers fabricated using this technology and compare these characteristics with those predicted from theory View full abstract»

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  • Polarization independent bidirectional fiber link using coherence multi/demultiplexing LiNbO3 integrated electrooptical circuits

    Publication Year: 1996 , Page(s): 1630 - 1638
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1252 KB)  

    We report recent results obtained in the area of bidirectional transmissions. We demonstrate the application of coherence modulation to such transmission systems using especially designed LiNbO3 integrated electrooptic circuits. We describe a system, formed by a pair of matched Mach-Zehnder interferometers integrated in Z-propagating lithium niobate substrate, whose peculiarity is to feature a polarization-independent behavior in the frame of digital transmissions. Considerations on crosstalk are also discussed. The experimental results deal with the demonstration of a bidirectional link with a data bit rate of 25 Mb/s View full abstract»

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  • Semiconductor cylinder fibers

    Publication Year: 1996 , Page(s): 1674 - 1676
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    We report on the fabrication and test of semiconductor cylinder fibers (SCFs). To date, we have used two semiconductors CdTe and CdS. Characterization indicates that the semiconductors survive the fabrication process. A number of fibers of each kind were fabricated with reproducible results View full abstract»

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  • Optimal design of IRIS-based polarimetric intrinsic fiber optic current sensors

    Publication Year: 1996 , Page(s): 1664 - 1673
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (856 KB)  

    Performance of reciprocity-compensated polarimetric fiber optic current sensors are analyzed for typical low-birefringence fibers. The intensity-based reciprocity-insensitive structure (IRIS) can effectively balance the birefringent and lossy influences in intrinsically low-birefringence fiber-based current sensors, while supplementary techniques such as wavelength control and pole-zero cancellation are needed to eliminate the strong polarization coupling effect in spun fiber-based sensors. It is shown from simulation that the stability of the sensor can be maximized by using the IRIS and a suitable initial birefringence View full abstract»

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Aims & Scope

The Journal of Lightwave Technology contains articles on current research, applications and methods used in lightwave technology and fiber optics.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Peter J. Winzer
Alcatel-Lucent Bell Labs