We report a wavelength tunable electro-absorption modulated DBR laser based on a combined method of SAG and QWI. The threshold current is 37mA and the output power at 100mA gain current is 3.5mW. When coupled to a single-mode fiber with a coupling efficiency of 15% ,more than a 20dB extinction ratio is observed over the change of EAM bias from 0 to -2V. The 4.4nm continuous wavelength tuning range covers 6 channels on a 100GHz grid for WDM telecommunications.
Three kinds of coplanar waveguides （CPWs） are designed and fabricated on different silicon substrates---common low-resistivity silicon substrate （LRS）, LRS with a 3μm-thick silicon oxide interlayer, and high-resistivity silicon （HRS） substrate. The results show that the microwave loss of a CPW on LRS is too high to be used, but it can be greatly reduced by adding a thick interlayer of silicon oxide between the CPW transmission lines and the LRS.A CPW directly on HRS shows a loss lower than 2dB/cm in the range of 0-26GHz and the process is simple,so HRS is a more suitable CPW substrate.
采用超低压(22×102Pa)选择区域生长(selective area growth,SAG)金属有机化学气相沉积(metal_organic chemical vapor deposition,MOCVD)技术成功制备了InGaAsP/InGaAsP级联电吸收调制器(electro absorption modulator,EAM)与分布反馈激光器(distributed feed backlaser,DFB)单片集成光源的新型光电器件.实验结果表明,采用该技术制备的器件具有良好的性能:激射阈值为19mA,出光功率为4·5mW,在5V的驱动电压下达到了20dB的消光比,器件3dB响应带宽达到了10GHz以上.应用这种新型器件,利用级联EAM的光开关效应,获得了重复率为10GHz、半高宽(full_width_at_half_maximum,FWHM)为13·7ps的超短光脉冲.
The wide stripe (15μm) selective area growth (SAG) of InGaAsP by low pressure MOVPE is systematically investigated.The characteristics of the growth ratios,thickness enhancement factors,bandgap modulation,and composition modulation vary with the growth conditions such as mask width,growth pressure.Flux of Ⅲ group precursors are outlined and the rational mechanism behind SAG MOVPE is explained.In addition,the surface spike of the SAG InGaAsP is shown and the course of it is given by the variation of Ⅴ/Ⅲ.
A semiconductor optical amplifier gate based on tensile strained quasi bulk InGaAs is developed.At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band filling effect.Moreover,the most important is that very low polarization dependence of gain (<0 7dB),fiber to fiber lossless operation current (70～90mA) and a high extinction ratio (>50dB) are simultaneously obtained over this wide 3dB optical bandwidth (1520～1609nm) which nearly covers the spectral region of the whole C band (1525～1565nm) and the whole L band (1570～1610nm).The gating time is also improved by decreasing carrier lifetime.The wide band polarization insensitive SOA gate is promising for use in future dense wavelength division multiplexing (DWDM) communication systems.
An improved butt coupling method is used to fabricate an electroabsorption modulator (EAM) monolithically integrated with a distributed feedback (DFB) laser.The obtained electroabsorption-modulated laser (EML) chip with the traditional shallow ridge exhibits very low threshold current of 12 mA, output power of more than 8 mW,and static extinction ratio of-7 dB at the applied bias voltage from 0.5 to -2.0 V.
A novel 1 55μm laser diode with spot size converter is designed and fabricated using conventional photolithography and chemical wet etching process.For the laser diode,a ridge double core structure is employed.For the spot size converter,a buried ridge double core structure is incorporated.The laterally tapered active core is designed and optically combined with the thin and wide passive core to control the size of mode.The laser diode threshold current is measured to be 40mA together with high slop efficiency of 0 35W/A.The beam divergence angles in the horizontal and vertical directions are as small as 14 89°×18 18°,respectively,resulting in low coupling losses with a cleaved optical fiber (3dB loss).
Monolithic electro absorption modulated distributed feedback(DFB) lasers are proposed and fabricated by using a modified double stack active layer.The 38mA threshold,9dB extinction ratio (from 0 5V to 3 0V),and about 5mW output power at the 100mA operation current are achieved.Compared with other reported results (only 1 5mW at the same operation current) of the traditional stack active structure,the proposed structure improves the output power of devices.
