- 學位論文
1310nm含電子阻障層之異質埋入式波導雷射之研究及動態特性量測
Characterization and Measurement of Dynamic Response for 1310 nm Buried-Heterostructure Laser Diodes with Electron-Stop Layer
摘要
現今使用於光纖通信的1310 nm波長LD光源，主動層所使用之材料系統主要分為兩大類：InGaAsP材料與AlGaInAs材料。然而前者具有較低的導電帶能隙差 (Conduction-Band Offset)，導致雷射二極體高溫操作特性不佳，因此，為提供優越的橫向光場侷限性、提高電流注入效率並增加材料熱導係數，於雷射波導結構設計上，可採用Buried-Heterostructure (BH)波導型式；此外，相較以AlGaInAs作為BH-type雷射二極體之主動層材料，採用InGaAsP材料可以避免鋁容易氧化而造成元件二次磊晶良率不佳的問題。為更進一步提高雷射二極體之熱穩定性，本研究更加入電子阻障層結構，解決載子因熱離子躍遷 ( Thermo-ionic transition) 所造成之損耗並提高主動層內部載子侷限性。 綜合上述，本論文以InGaAsP材料為主動層，製作具備電子阻障結構之掩埋式異質結構(Buried-Heterostructure)波導雷射。以期提升元件高溫的忍耐性，並且有效降低串聯電阻降低因I2R產生的熱源，使得雷射工作效率提升，也相對滿足通訊協定之操作標準，降低通訊模組散熱問題以節省安裝TE cooler 之製作成本，大大增加市場競爭力。另外，雷射光束之發散角將左右光纖耦光效率，一旦θ┴-θ//比例能接近1，雷射輸出圖樣會接近理想之圓型光束，提高光纖耦光效率。由實驗結果顯示，元件之室溫臨界電流約在12mA，單邊轉換效率為0.235 W/A，遠場角之θ┴-θ//比例為1.17；此外，為提升實用性與市場應用價值，本元件最後經由TO-56 Header封裝成通訊次模組。透過動態量測分析，大訊號調變頻寬可達10Gbps，小訊號調變頻寬亦可達9.17GHz。
並列摘要
Nowadays, laser diodes (LDs) emitted at 1310 nm have extensively been used in optical fiber communications. Generally, there are two preferable gain mediums commonly be used as the active layers, i. e., InGaAsP and AlGaInAs-based material systems. However the former has the lower conduction-band offset that would cause the degraded performance of LDs at high temperatures. To provide superior optical field confinement, efficient current injection and higher material thermal conductivity, the waveguide structure is made from buried-heterostructure (BH). In addition, the material for active region consists of InGaAsP system, therefore, the regrowth techniques have high yield due to Al-free and no material oxidizing. Furthermore, in order to enhance thermo-stability and to decrease carrier losses from thermo-ionic transition, the electron-stop-layer is constructed near active region and forms an additional electron barrier, lead to higher carrier confinement. Based on mentioned above, in this study, the 1300 nm InGaAsP BH LDs with electron-stop-layer were fabricated. We expect that these LDs would present promoted thermal characteristics and could decrease series-resistance to lower Joule effects (I2R) and to achieve high quantum efficiency. Besides, it will ensure the strength of competition in the communication market by broadening LDs’ modulation bandwidth, satisfying the 10 Gb Ethernet standard, and eliminating the Peltier cooler. On the other hand, since the far field angle and distribution pattern of laser output beam will dominate the coupling efficiency, the relatively high coupling efficiency will be obtained by tailoring output beam as circular one. In other words, the ideal case for the far field pattern is that the ratio between θ┴ and θ// can approach 1. By the experimental result, it demonstrates that in room temperature the threshold current of LDs is 12 mA, the as-cleaved single facet slope efficiency is approximately 0.235 W/A, the far field angle ratio of θ┴-θ// is 1.17; In addition, take industrial applications and business values into consideration, the devices finally were packaged by TO-56 header as subassembly modules. By the dynamic measure analysis, the large signal modulation bandwidth is as high as 10Gbps; the small signal modulation bandwidth may also higher than 9.17GHz.