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Selected Topics in Quantum Electronics, IEEE Journal of

Issue 6 • Date Dec. 1997

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Displaying Results 1 - 17 of 17
  • High-temperature operation of 1.3-/spl mu/m tapered-active-stripe laser for direct coupling to single-mode fiber

    Page(s): 1399 - 1404
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (138 KB)  

    High-temperature operation of 1.3-μm wavelength multiquantum-well (MQW) lasers with an active stripe horizontally tapered over whole cavity, for direct coupling to single-mode fibers (SMFs), are reported. The lasers have reduced the output-beam divergence in a simple structure which does not contain an additional spot-size transformer. To improve high-temperature characteristics, we have investigated the influence of the thickness of separate-confinement-heterostructure layers and the number of quantum wells (QWs) on the threshold current and the output-beam divergence at high temperature. As a result, the fabricated lasers show low-threshold current (∼18 mA) and high-slope efficiency (∼0.4 mW/mA) with narrow output-beam divergence (∼12°) at 85°C. Moreover, we have obtained maximum coupling efficiency of -4.7 dB in a direct coupling to a SMF, and the reliability of longer than 10 5 h (MTTF) by a lifetime test of over 2000 h at 85°C. View full abstract»

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  • Passive alignment of second generation optoelectronic devices

    Page(s): 1441 - 1444
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    This paper details how expanded-mode semiconductor devices and passive alignment techniques can be used to realize low-cost high-performance fiber grating laser and laser amplifier packages for future generations of optical telecommunication systems View full abstract»

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  • Introduction to the issue on alignment tolerant structures for ease of optoelectronic packaging

    Page(s): 1306 - 1307
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    Is an introduction on a special issue on optoelectronic packaging scientific articles View full abstract»

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  • Reliable wide-temperature-range operation of 1.3-μm beam-expander integrated laser diode for passively aligned optical modules

    Page(s): 1405 - 1412
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    A novel structure for a 1.3-μm beam-expander integrated (BEX) laser diode is demonstrated. It combines a thickness-tapered InGaAsP-InP multiple quantum-well (QW) crystal grown by a novel silicon shadow masked metalorganic vapor phase epitaxy and a simple reverse-trapezoid-ridge waveguide laser structure that offers smooth mode field expansion and improved high-temperature lasing performance. We found this new BEX laser quite suitable for operation over a wide range of temperatures above 85°C and highly efficient lens-free coupling to a single-mode fiber (SMF) of less than 3 dB. These excellent lasing properties along with reliability under severe environmental conditions make this BEX-LD a promising candidate for practical use for low-cost long-wavelength light-source modules using optical passive alignment techniques View full abstract»

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  • A review on fabrication technologies for the monolithic integration of tapers with III-V semiconductor devices

    Page(s): 1308 - 1320
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    The past few years a lot of effort has been put in the development and fabrication of III-V semiconductor waveguiding devices with monolithic integrated mode size converters (tapers). By integrating a taper with a waveguide device, the coupling losses and the packaging cost of OEICs in future fiber-optical networks can be much reduced. This paper gives an overview of different taper designs, the possible fabrication technologies and performances of tapered devices View full abstract»

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  • Structural dependence of 1.3-μm narrow-beam lasers fabricated by selective MOCVD growth

    Page(s): 1413 - 1420
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    The effect of structural parameters on the lasing characteristics of 1.3-μm narrow beam lasers has been investigated. Monolithically integrated vertically tapered multiquantum-well (MQW) waveguide, fabricated by use of selective metal-organic chemical vapor deposition (MOCVD), is used for the expansion of the optical spot size. It is experimentally shown that the energy separation between the gain and waveguide regions that is formed simultaneously by selective MOCVD is shown to be an important parameter in order to achieve low-threshold current density and good temperature characteristics. The lengths of gain and waveguide regions have been investigated in terms of temperature characteristics of threshold current and far-field angle. A lower threshold current density and a higher characteristic temperature were obtained for longer gain region, We also have estimated the waveguide loss of the mode-field converter lasers diodes (MFC-LD's). High performance of 1.3-μm integrated vertically tapered waveguide lasers were achieved in an optimized device View full abstract»

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  • 1.55-μm InGaAsP-InP laser arrays with integrated-mode expanders fabricated using a single epitaxial growth

    Page(s): 1332 - 1343
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    We report on two techniques for the realization of expanded-mode laser arrays with a single epitaxial growth step and conventional fabrication techniques. Laser arrays with integrated adiabatic-mode expanders (AME) based on a tapered active region and an underlying passive coupling waveguide are demonstrated at the 1.55-μm wavelength. These lasers butt couple to standard cleaved single-mode fibers (SMF's) with a loss of only 3.6 dB. This coupling efficiency compares with a theoretical calculation of 3.2 dB. We also propose a novel realization of a laser with an integrated-mode expander based on resonant coupling between a tapered active waveguide and an underlying coupling waveguide. Three-dimensional (3-D) beam propagation method (BPM) results are presented which show that compact, efficient mode expanders with a mode transformation loss of only 0.36 dB can be realized using this method. Butt-coupling efficiencies of 2.6 dB are possible to standard cleaved single-mode fibers View full abstract»

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  • Tapered rib adiabatic following fiber couplers in etched GaAs materials for monolithic spot-size transformation

    Page(s): 1361 - 1371
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    Design details and demonstration data are presented for an (Al,Ga)As monolithic tapered rib waveguide achieving modal spot-size transformation. The tapered rib adiabatic following fiber coupler structure (TRAFFIC) achieves two-dimensional (2-D) expansion of the output optical mode of single-transverse-mode semiconductor waveguide modulators and lasers using a one-dimensional (1-D) taper between noncritical initial and final taper widths which are compatible with optical lithographic techniques. Measurements are presented of total mode expansion losses between ~1.5-2.0 dB and semiconductor to single-mode-fiber waveguide coupling losses of ~0.5-1.0 dB for doped pin optical-modulator-type waveguides using the TRAFFIC waveguide. A semiconductor laser with a TRAFFIC tapered-rib mode-expansion section and measured coupling loss between the laser output and single-mode fiber of only 0.9 dB is described. Finally, a TRAFFIC Spot-size transformer for undoped waveguide modulators with total mode expansion losses of 1.84 dB and excellent modal behavior at 1.32-μm wavelength is presented. The TRAFFiC structure is particularly well suited for integration with both active and passive etched rib waveguide devices. Fabrication is relatively simple, requiring only patterning and etching of the tapered waveguide and uniform-width outer mesa waveguide without any epitaxial regrowth View full abstract»

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  • Semiconductor optical amplifier array coupled to uncoated flat-end fibers with integrated beam expanders and TiO2 antireflection coatings

    Page(s): 1421 - 1428
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    We present a novel coupling scheme consisting of an integrated beam expander, a specifically tailored TiO2 antireflection coating, optical index matching gel, and uncoated flat-end single-mode fiber (SMF). This scheme was used to package four-channel semiconductor optical amplifier arrays. Far-field profiles for each discrete amplifier in the array are typically 80 and 150 FWHM, perpendicular and parallel to the junction plane, respectively. The TiO2 AR coating overcomes the indices mismatching of fiber glass and InP based device, and reduce optical reflection to 0.002% at 1.55 μm. Misalignment tolerance in the l-dB excess loss range, for a discrete channel, is typically 5 μm vertically and 8 μm laterally. The average coupling loss is 4.3 dB per facet for the devices measured. Fiber coupled small signal gain for the amplifiers is typically 11.6 dB and a saturation output power of 3.0 dBm. The method of characterization and optimization of the TiO2 coating is discussed View full abstract»

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  • High-power low-divergence semiconductor lasers for GaAs-based 980-nm and InP-based 1550-nm applications

    Page(s): 1344 - 1350
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB)  

    High-power diode lasers with low-vertical divergence and high-fiber coupling efficiency were developed for GaAs-based 980-nm pump lasers and InP-based 1550-nm Fabry-Perot and distributed-feedback (DFB) lasers. Narrow divergence at 980 nm was made possible by a large optical-mode waveguide design, with full-width at half-maximum (FWHM) far-field angles of 11.7°×17.8° and coupling efficiency of 80% into a cleaved single-mode fiber (SMF). A vertical taper processing technique was developed for InP-based laser structures. Fabry-Perot lasers produced over 90-mW output power, 17°×16° FWHM beam divergence angles, and 63% coupling efficiency into a lensed SMF. The vertical taper was successfully integrated in 1550-nm DFB lasers, and over 80 mW single-mode output power with beam divergence angles of 12°×14° was obtained View full abstract»

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  • 1.3-μm spot-size-converter integrated laser diodes fabricated by narrow-stripe selective MOVPE

    Page(s): 1392 - 1398
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB)  

    High-performance 1.3-μm spot-size-converter integrated laser diodes (SSC-LDs) have been developed by using narrow-stripe (<2.0 μm) selective MOVPE. In order to decrease leak current at high temperature, a p-n-p-n current blocking structure was added using a self-alignment process. These LD's no longer require a semiconductor etching process. Superior lasing characteristics, such as a low driving current of 56 mA for output power of 10 mW, and high-slope efficiency at 85°C, were achieved by using a high-quality multiple-quantum well (MQW) active layer of narrow-stripe selective MOVPE and a p-n-p-n current blocking structure. A narrow radiation angle of 12° was obtained by optimizing the tapered-waveguide profile. A high-coupling efficiency of -2.8 dB was achieved between a LD chip and a single-mode fiber (SMF). This SSC-LD is very appropriate as a light source for access network systems, which require a low-cost LD module. It has excellent coupling efficiency, using a SMF, and a simple fabrication process, using selective MOVPE View full abstract»

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  • Narrow-beam divergence 1.3-μm multiple-quantum-well laser diodes with monolithically integrated tapered thickness waveguide

    Page(s): 1384 - 1391
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    This paper describes the optimum design, fabrication, and performance of a 1.3-μm multiple-quantum-well (MQW) laser diode monolithically integrated with a tapered thickness spot-size transformer. The dependence of the lasing characteristics on the thickness distribution of the core layer and on the current injection profile of the device were analyzed. This integrated laser with its optimized structure performed at a low threshold current of 22.2 mA, even at 85°C. The integrated spot-size transformer effectively reduced the lateral and vertical far-field FWHM's to 8° and 9°, respectively. A very long lifetime of over 1×105 h was estimated at 85°C and 8 mW under CW operation View full abstract»

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  • Optical-mode transformer: a III-V circuit integration enabler

    Page(s): 1321 - 1331
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    Further development in optical fiber communications at 1.3 and 1.5 μm not only requires the improvement of components, but also hinges on the capability to fabricate optoelectronic circuits on a mass scale. Hybrid and monolithic integration of these components are expected to yield the means to mass produce optoelectronic circuits with the required characteristics. Effort is currently deployed to find simplified ways to optically interconnect such diverse components as lasers, modulators, waveguides, switches, filters and detectors, either by fiber pigtailing, hybridization on a Si-motherboard; or by monolithic integration on a single chip of InP. In this paper, emphasis is placed on the efficiency of optical-mode transformer (OMT) as a versatile solution to overcome the main technological obstacles of optical interconnection between InP-based components. A few examples will highlight the enabling qualities for fiber pigtailing and photonic integration View full abstract»

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  • Coupling and conversion characteristics of spot-size-converter integrated laser diodes

    Page(s): 1351 - 1360
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    The coupling and conversion characteristics of four types of spot-size converter integrated laser diodes (SS-LDs) to a single-mode fiber (SMF) in the 1.3-μm-wavelength region are numerically clarified. The SS-LDs are categorized into types with vertical tapers and types with a combination of a lateral taper and a thin-film core. The eigenmodes are obtained by the finite-element method (FEM). The semivectorial 3-D finite-difference (FD) beam propagation method (BPM) is used to calculate the propagating beams View full abstract»

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  • Self-aligned packaging of an 8×8 InGaAsP-InP space switch

    Page(s): 1445 - 1456
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    By using an efficient and alignment tolerant fiber-chip coupling technology we can realize semiconductor space switches with a new and highly promising modular architecture. We present a completely packaged 8×8 matrix switch based on InGaAsP-InP intended for routing applications around wavelength 1.55 μm. The matrix is composed of sixteen 1×8 InGaAsP-InP switches that are optically interconnected by a shuffle comprising 64 single-mode fibers (SMFs). All the fiber ports of the InGaAsP-InP chips are provided with monolithically integrated optical spot-size transformers (MOSTs) that allow simple yet highly efficient self-aligned multifiber coupling. The 8×8 matrix shows a fiber-matrix-fiber insertion losses of 20 dB and a crosstalk suppressions of 28 dB. An extension of the matrix architecture to a 64×64 switch seems straightforward View full abstract»

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  • Monolithic integration of spot-size converters with 1.3-μm lasers and 1.55-μm polarization insensitive semiconductor optical amplifiers

    Page(s): 1429 - 1440
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    To reduce packaging costs, it is necessary to use passive alignment between the laser diodes and optical fiber. Such an alignment requires low-coupling loss and large positional alignment tolerances. This is achievable with integrated spot-size converters, which permit to match the near field of a laser to that of a flat-end single-mode fiber (SMF). In this paper, we first review briefly the different technological approaches to realize spot-size converters. Then, we focus on the double-core structure developed both for 1.3-μm Fabry-Perot lasers and 1.55-μm semiconductor optical amplifiers (SOAs). The spot-size expansion is simulated using a two-dimensional (2-D) beam propagation method analysis. Short spot-size converters (100 μm) integrated with 1.3-μm lasers and 1.55-μm SOAs exhibit beam divergences as low as 12°×12° and 12°×15°, respectively. The performances of devices with integrated spot-size converters are reported and discussed. A 2-in wafer process is used thanks to the versatility of the double-core structure and its compatibility with buried ridge stripe technology View full abstract»

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  • Laser diodes with integrated spot-size transformer as low-cost optical transmitter elements for telecommunications

    Page(s): 1372 - 1383
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    We have realized laser diodes with integrated spot-size transformer to achieve a high-coupling efficiency to a standard single-mode fiber (SMF) without microoptical elements. A coupling loss of about 1 dB has been achieved with tolerances of 12 μm in both vertical and horizontal direction. We have fabricated both distributed-feedback (DFB) and Fabry-Perot (FP)-type lasers. In the case of the FP lasers the longitudinal single-mode emission was stabilized by means of an external fiber Bragg-grating which was directly butt-coupled to the laser. We have experimentally and theoretically investigated the optical and electrical properties of the devices using a transmission line model View full abstract»

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Aims & Scope

Papers published in the IEEE Journal of Selected Topics in Quantum Electronics fall within the broad field of science and technology of quantum electronics of a device, subsystem, or system-oriented nature.

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Editor-in-Chief
John Cartledge
Queen's University