DFB lasers with monolithically integrated passive waveguide

Novel MQW integrated passive waveguide (IPW) DFB lasers have been fabricated using a selective area MOVPE growth technique. Detailed measurements of the absorption loss of the passive waveguide in the structure as well as its influences on the laser linewidth are reported for the first time. A linewidth reduction factor of more than 3 is observed as compared to a simple DFB laser despite the high absorption loss     

Monolithic waveguide coupled cavity lasers and modulatorsfabricated by impurity induced disordering

Describes results on AlGaAs integrated optoelectronic devices consisting of combinations of buried passive waveguide regions with active multiple quantum well gain regions. The authors have developed a technique for accomplishing this integration in which the waveguide regions have greatly reduced propagation loss at the gain wavelength of the active media. They have incorporated sections of waveguide into laser cavities, and the resulting low (7-11 mA) threshold currents and weak dependence of threshold current on waveguide length confirm the reduced loss and waveguiding nature of the waveguide regions. They have used these structures to monolithically couple laser amplifiers to electroabsorption modulators. Among their results on these devices are electroabsorption modulators with contrast ratios of 23:1 and monolithic Q-switch operation resulting in pulse widths of less than 200 ps. The relative simplicity with which these structures are fabricated via impurity induced disordering techniques promises to result in major impact on practical systems for monolithic integration     

Novel fabrication-tolerant twin-guide laser structure with anexternal passive waveguide

The authors propose a novel quasi-symmetrical twin-guide GaAs/AlGaAs laser structure (QSTGL) with a low-loss external passive waveguide. The device is tolerant to fabrication misalignment and therefore well suited for monolithic integration. Threshold current densities of less than 1.1 kA/cm² and a coupling efficiency between 70 and 80% into the low-loss passive waveguide are achieved     

Measurements of coupling and reflection characteristics of butt-joints in passive waveguide integrated laser diodes

Amplified spontaneous emission (ASE) spectra of passive waveguide integrated lasers have been studied to estimate the coupling efficiency and the reflectivity at the butt-joints between active and passive waveguides. A new method has been proposed for the analysis of ASE to extract the coupling efficiency and reflectivity at the butt-joints. This method was applied experimentally to estimate the coupling and reflection of the passive waveguide integrated lasers with different amounts of vertical misalignments of active and passive waveguides.     

Ytterbium-doped glass waveguide laser fabricated by ion exchange

A ytterbium-doped, glass, channel waveguide laser, fabricated by ion exchange, is reported. The 2.2 cm long device, using broad-band 4% output couplers, lased in the vicinity from 1020 to 1030 nm when pumped by a Ti:sapphire laser operating at 910 nm. A lasing threshold of 50 mW (launched pump) and a slope efficiency of 5% were measured. Device parameters, including fluorescence lifetimes, emission and absorption cross sections, propagation losses, and mode profiles were experimentally determined and laser performance was analytically modeled using this data     

Tunable electroabsorption modulated laser integrated with a bent waveguide distributed-feedback laser

The fabrication of the first 1.55-/spl mu/m wavelength tunable electroabsorption modulated laser integrated with a bent waveguide distributed-feedback laser is reported. A low-threshold and stable single-mode operation is obtained when the devices were uniformly pumped. A single-mode output power close to 10 mW from a single-mode fiber (40 mW in free space) is obtained with a 0 V bias to the modulator and an extinction ratio of up to 15 dB at 2.5 V. This single mode stability is due to the continuously distributed phase shift implemented in the structure. With a nonuniform injection, it was possible to select one particular mode out of the three neighboring modes inside the broad-reflection band of the reflector. A tuning range of 3.5 mm was obtained while maintaining an output power of more than 2 dBm from each mode.     

Transform-limited picosecond optical pulses from a mode-lockedInGaAs/AlGaAs QW laser with integrated passive waveguide cavity and QWmodulator

Using a novel single-top molecular beam epitaxy growth technology on nonplanar substrates, an InGaAs/AlGaAs laser amplifier has been integrated with a 4-mm-long passive waveguide cavity and a QW modulator. Lasing action of the entire structure was achieved by a current of 60 mA flowing through the amplifier section. Mode-locking experiments in which an RF signal was applied to the modulator segment led to nearly-transform-limited pulses with a duration of 4.4 ps and a time-bandwidth product of 0.43     

连续偏光干涉法测量波片宽波段延迟量变化

为了测量石英波片宽光谱下相位延迟量,根据连续偏光干涉原理,提出了一种新的测量方法,并给出了相应波长的延迟量数据处理办法。采用岛津UV-3101PC分光光度计双光路比对测量方法,增加了采集数据的稳定可靠性,获得了已知厚度的石英波片300nm~800nm波段的连续偏光干涉谱,进行了理论分析和实验验证,获得了波片的宽光谱相位延迟量数据。结果表明,实验曲线和理论曲线吻合较好,测量平均误差不大于2°。这一结果对研究波片延迟量色散性质以及工艺进程的引导有重要实际意义。     

GaInAsP/InP integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide

A novel GaInAsP/InP integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide (BJB-DBR integrated laser for short) is proposed and demonstrated. In this structure, it is found theoretically that an efficient coupling of 98% between the active and butt-jointed external waveguides is available by matching the propagation constants and the field profiles of both waveguides, which gives relatively larger fabrication tolerance. Prototype BJB-DBR integrated lasers with emitting wavelength of 1.55 ?m were fabricated, and single-longitudinal-mode operation was obtained at room temperature.     

Realization of novel low-loss monolithically integrated passive waveguide mode converters

The novel design and fabrication of monolithically integrated passive waveguide mode converters (WMCs), realized through the utilization of the reactive ion-etch lag (RIE Lag) phenomenon, is reported. The low-loss GaAs-AlGaAs WMCs have been characterized over a wavelength range of 900-940 nm, resulting in TE-TM (TM-TE) mode conversion with efficiencies of greater than 96% and low-loss devices with conversion lengths as short as 150 /spl mu/m. The properties and characteristics of the fully integrated WMCs, fabricated with a single masking and etch process, are in agreement with theoretical predictions.     

Short-cavity distributed Bragg reflector laser with an integrated tapered output waveguide

A distributed Bragg reflector strained-layer multiple-quantum-well laser at 1.5- mu m wavelength with an integrated tapered waveguide beam expander is discussed. The far-field FWHMs in the lateral and vertical directions are 10 and 15 degrees , respectively. A quantum efficiency of 17% out the tapered facet was measured with a corresponding threshold current of 28 mA. The alignment tolerances for coupling into a cleaved single-mode fiber are 9.5 and 7.5 mu m FWHM in the lateral and vertical directions, respectively. A 3-dB improvement for single-mode fiber coupling using a SELFOC lens was obtained.<>     

Monolithically integrated transverse-junction-stripe laser with anexternal waveguide in GaAs/AlGaAs

This device consists of a five-layer transverse-junction-stripe laser structure monolithically integrated with an external three-layer waveguide. The transverse p-n junction within the laser cavity permits the use of a vertical p-n junction in the external waveguide for future implementation of a modulator without disturbing the laser operation. As a result, this structure allows for flexibility in the design of the external waveguide/modulator without resorting to complicated regrowth procedures. Design curves for two different types of optical cavities are presented, and the reflectivity and transmission of the etched facet as a function of active layer thickness is modeled in detail using an excitation field approach. Finally, integrated laser/waveguide devices are fabricated based on this design and are compared to the theoretical curves. Most devices had threshold currents between 60 and 80 mA, while laser-to-waveguide transmission coefficients were as high as 38%     

Lossless electroabsorption modulator monolithically integrated with a semiconductor optical amplifier and a passive waveguide

We have developed a monolithic integrated device consisting of an electroabsorption modulator and a semiconductor optical amplifier (SOA) connected by a deep-ridge passive waveguide by means of butt-joint selective area growth. Lossless operation with a high extinction ratio of 32 dB and clear eye opening at 10 Gb/s are successfully achieved. We confirm that the optical injection should be from the SOA side of the device to obtain a wide error-free range of incident optical power from -20 to +10 dBm. Our device could lead to richly functional photonic integrated circuits comprising arrayed waveguide gratings (AWGs) for advanced wavelength-division-multiplexing networks, since the passive waveguide has the same structure as AWGs.     

Integration of a laser diode with a polymer-based waveguide forphotonic integrated circuits

The fabrication and characterization of BRS lasers monolithically integrated with butt-coupled polymer-based buried strip waveguides is presented. Threshold currents of lasers with one cleaved and one etched mirror facets are 15-18 mA and waveguide output powers are in excess of 5 mW at 100 mA laser driving currents and for 600 μm long waveguides. The device exhibits a total waveguide insertion loss less than 5 dB. The integrated device is potentially suitable as a building-block for photonic integrated circuits     

量子阱激光二极管泵浦单块Nd∶YLF激光器

用多量子阱激光二极管列阵(MQW-LDA)泵浦单块Nd:YLF激光器,脉冲工作,获得1.047μm的线偏光输出。阈值泵浦功率6.8mW,斜率效率为24％,输出脉冲能量达6.7μJ;用增益开关获得50mW的峰值功率输出。理论计算了泵浦阈值、斜率效率,获得了增益开关的数值解结果,与实验基本一致。     

InGaAsP-InP integrated twin-guide laser diode with grooved cornerreflector fabricated by reactive ion beam etching

By introducing grooved comer reflectors at the cavity of an integrated twin-guide laser diode (ITG-LD), optical loss can be reduced, and travelling wave characteristics such as mode purity are simultaneously enhanced. The fabricated device shows single-mode operation at current levels up to 1.4 times threshold     

Device characteristics of GaAlAs buried-multiquantum-well lasers fabricated by Zn-diffusion-induced disordering

A new transverse mode controlled buried-multiquantum-well (BMQW) laser has been fabricated using the simple and reliable Zn-diffusion-induced disordering process. BMQW lasers are characterized by low threshold current (20 mA) and single transverse and longitudinal mode oscillation. It is observed that the threshold current is proportional to the stripe width and the transverse mode is controlled by controlling the stripe width. From these results, it is confirmed that the BMQW structure provides good optical confinement as well as current confinement.     

Rigorous analysis of coupling between laser and passive waveguidein multilayer slab waveguide

An approach that combines the finite-element and boundary-element methods (FEM/BEM) is extended to the analysis of arbitrarily shaped discontinuities in a multilayer slab waveguide. Here all the eigenmodes, namely, guided modes, substrate radiation modes, and substrate-cover radiation modes, are taken into account and are constructed by an extended matrix method. Computed results are given for the rigorous analysis of the coupling between a five-or six-layer laser and a four-layer passive waveguide in a monolithically integrated circuit. Some of the results are for multimode incidence. Since the coupling is one of the most important discontinuity problems in practice, this result confirms the usefulness of the approach     

Passively aligned hybrid WDM module integrated with spot-sizeconverter integrated laser diode and waveguide photodiode on PLCplatform for fibre-to-the-home

A low cost and high performance hybrid WDM module assembled by passive alignment has been developed for FTTH systems. High coupling efficiency of a spot-size converter integrated laser diode to a PLC waveguide, which facilitates mass production of the module, is achieved. A minimum optical received power of -37 dBm for a 50 Mbit/s burst signal is also achieved     

The design and the fabrication of monolithically integrated GaInAsP MQW laser with butt-coupled waveguide

We optimized the etching process for butt coupling to improve the reproducibility and the uniformity of the process for the integrated GaInAsP multiquantum-well laser with a butt-coupled waveguide. Three different ways of etching process were tested, which are reactive ion etching (RIE), RIE followed by a small amount (50 nm thick) of selective wet etching, and RIE followed by an adequate amount (125 nm thick) of selective wet etching. RIE followed by an adequate amount of selective wet etching showed the superior properties to the common expectation on RIE only, giving the measured coupling efficiency 96/spl plusmn/1.7% versus 34/spl plusmn/8%. The high coupling efficiency and the very small variation across a quarter of a 2-in wafer demonstrate that RIE coupled with an adequate amount of selective wet etching can also replace the conventional process for butt coupling, RIE followed by HBr-based nonselective wet etching, to fabricate high-quality integrated photonic devices.