Quasicontinuous wavelength tuning in super-structure-grating (SSG)DBR lasers

The paper describes the design of a super-structure-grating distributed Bragg reflector (SSG-DBR) laser for broad quasicontinuous wavelength tuning with stable single-mode operation. The phase distributions and the effective coupling coefficients of SSG's are optimized to obtain both broad tuning range and high mode selectivity. A computer-aided simulation of wavelength tuning, where the effects of the waveguide loss increase and inhomogeneous gain spectrum are included, provides an optimum cavity structure and indicates the possibility of more than 70 mm quasicontinuous tuning in a 1.55 μm InGaAsP-InP SSG-DBR laser. Experimental results for 34 nm quasicontinuous tuning with a properly designed device are also presented     

Broad-range wavelength tuning in DBR lasers with super structuregrating (SSG)

Broad-range wavelength tuning is demonstrated in tunable distributed Bragg reflector (DBR) lasers with the super structure grating (SSG) proposed. The SSG is fabricated by electron beam exposure lithography. The grating performance is measured by transmittance characteristics of the SSG reflector. A maximum tuning range of 63 nm is obtained under the CW condition while keeping a single longitudinal mode. In a 50-nm tuning range, the threshold current variation is as low as 5.0-9.5 mA     

Ridge waveguide sampled grating DBR lasers with 22-nmquasi-continuous tuning range

We demonstrate a ridge waveguide sampled-grating distributed-feedback laser with continuous wavelength coverage over a 22-nm tuning range, the largest ever reported for a ridge waveguide structure. The design is based on a 400-nm-thick 1.4-μm bandgap waveguide optimized for carrier injection tuning with offset quantum wells used to form the active region. The offset quantum wells enabled the device to be fabricated with only a single metal-organic chemical vapor deposition regrowth step. By tuning both mirror sections and the phase control section we were able to obtain 27 wavelength-division-multiplexed channels spaced at 100 GHz and precisely centered on the ITU grid with equal output power and greater than 40 dB of sidemode suppression ratio     

Influence of mode competition on the fast wavelength switching ofthree-section DBR lasers

For a three-section distributed Bragg reflector (DBR) laser, the dependence of the intermodal wavelength-switching time on the precise wavelengths within two longitudinal modes is examined experimentally and theoretically. When switching from a fixed wavelength in the central region of the tuning curve for one mode to a second wavelength on the tuning curve for another mode, a significant variation of the switching delay occurs as the second wavelength spans the mode tuning curve. Mode competition is identified as being responsible for this variation     

Broad range (34nm) quasi-continuous wavelength tuning insuper-structure-grating DBR lasers

The authors present super-structure-grating distributed Bragg reflector lasers that provide a quasi-continuous wavelength tuning of 34 nm with stable singlemode oscillation     

Over 1100 nm wavelength tuning in superstructure grating (SSG) DBR lasers

A broad range tuning of over 100 nm in tunable DBR lasers with superstructure grating (SSG) is reported. The SSG reflectors for 100 nm were designed and patterned by electron beam lithography. 1.55 mu m DBR lasers with SSG reflector operate in a single mode with a tuning range of 83 nm under CW conditions. With inclusion of the multimode operating region, the tuning range becomes as wide as 103 nm.<>     

Characteristics of super structure grating (SSG) DBR lasers underbroad range wavelength tuning

Spectral characteristics of the super structure grating (SSG) distributed Bragg reflector (DBR) lasers under broad range wavelength tuning are discussed. SSG DBR lasers show good spectral characteristics with broad range wavelength tunability. Under the directly intensity modulated condition, stable single longitudinal mode oscillations are also obtained over the broad wavelength tuning range     

Extended tuning range in sampled grating DBR lasers

The authors demonstrate, for the first time, successful implementation of a distributed Bragg reflector laser with two sampled grating mirrors, which they previously predicted should give tuning range in excess of 50 nm. This device uses a uniform grating pitch throughout the structure, and relies on the same fabrication technology as a standard DBR laser. Initial results show 57 nm of mathematical tuning at 1.475 μm with side-mode suppression ratio (SMSR)>30 dB over much of the tuning range. The observed change in operating wavelength versus mirror currents along with below threshold spectra agree with theoretical expectations     

Dynamic wavelength tuning characteristics of the 1.5-μmthree-section DBR lasers: analysis and experiment

We present a detailed theoretical analysis of the static and dynamic tuning characteristics of 1.55-μm region three-section tunable DBR lasers under discrete tuning and under continuous tuning. We have analyzed the oscillating wavelength, the Bragg wavelength, and output power characteristics using the rate equation that considers the thermal effect, simultaneously analyzed the heat transfer equation, considering the heat transfer among passive waveguides, the LD chip, the submount, and the heat sink. We experimentally confirm the static and dynamic wavelength tuning characteristics using a highly accurate heterodyne measurement system. Static and dynamic characteristics simulated using the three-section DBR laser model and the thermal model agree with the experimental results presented in this paper     

Wavelength tuning analysis and spectral characteristics ofthree-section DBR lasers

A theoretical model for the design of three-section distributed Bragg reflector (DBR) lasers using the transfer matrix method is presented. The oscillation parameters, the tuning behavior, and the linewidth are derived. The effect of a discontinuity of the waveguide at the active-passive interface is accounted for by using scattering matrix parameters, easily combined with the transfer matrix method. The influence of such an interface is studied and the importance of optical losses at this point is discussed     

Continuous wavelength tuning in micromachined Littrow external-cavity lasers

This work presents the theory and experiment of the wavelength continuously tunable lasers, whose external cavities are constructed by the microelectromechanical systems (MEMS) technology. The theoretical study reexamines the wavelength tuning theory and adapts it to the MEMS tunable lasers under special concerns of the system properties such as short cavity length and prealigned component position. It is shown that in the MEMS Littrow lasers a mode-hop-free wavelength tuning requires a moving pivot, or in other words, a fixed pivot has only limited tuning range. In addition, it is also found that the wavelength dependence of the gain medium refractive index significantly affects the wavelength tuning range. Based on the theoretical study, a tuning structure is fabricated by the deep reactive ion etching (DRIE) on a silicon-on-insulator (SOI) wafer, and hybridly integrated with a gain chip and an optical fiber. The laser has dimensions as small as 2.0 mm/spl times/1.5 mm/spl times/0.6 mm, and can be tuned continuously over 30.3 nm at a resolution of 0.03 nm/V/sup 2/. As a comparison, another MEMS tunable laser designed according to the conventional theory has only a tuning range of 5.9 nm.     

Design and fabrication of ridge waveguide folded-cavity in-planesurface-emitting lasers

A 45° angled reactive ion etching combined with an in situ monitoring technique was used to fabricate ridge waveguide folded-cavity in-plane surface-emitting lasers. This laser structure, with two 45°C angle-etched internal total-reflection mirrors and an epitaxially grown distributed Bragg reflector, is very promising for OEIC applications. Laser-structure design and laser fabrication are addressed. A continuous-wave threshold current of 8 mA, the lowest reported in the literature, was achieved on 3-μm-wide, 350-μm long devices     

窄脊型波导半导体激光器偏振与横模关系研究

基于有效折射率法建立了窄脊型波导数值计算模型,通过实验研究了InGaAs量子阱窄脊型波导半导体激光器偏振特性与横模之间的关系。根据理论计算,脊型波导中类TM模式在慢轴方向的有效折射率差更大,类TM模式的限制因子比类TE模式的限制因子更大、更容易出现慢轴高阶模式;而随着脊型波导的高度增加,快轴高阶模式被截断,类TE₀₀模式的限制因子逐渐增加至与类TM₀₀模式相近,慢轴高阶模式因其大的散射损耗被抑制,理论上可实现高偏振度、高光束质量激光输出。在实验方面,利用量子阱材料的增益偏振特性,通过脊型高度与宽度的设计,制备了高偏振度、基横模的窄脊型波导半导体激光器。     

All-optical wavelength tuning in solc filter based on TI:PPLN waveguide

All-optical wavelength tuning in a waveguide-type Solc filter based on a Ti:PPLN waveguide has been demonstrated for the first time by ultraviolet illumination. The measured wavelength tuning rate as a function of the UV intensity was about -26.42 nm/W cm^-2.     

低阈值电流、高量子效率脊形波导激光器

研制了低阈值电流、高量子效率670nm压缩应变单量子阱GaInP/AIGalnP脊形波导激光器。测量解理成的激光器条,腔长为300μm时,阈值电流为12．8mA,双面外部量子效率之和达到94．6％。     

Measurements of low frequency and high frequency relative intensity noise in DBR lasers

The relative intensity noise in DBR lasers has been measured as a function of the grating current in both the low frequency and high frequency regimes. With increasing grating current, large increases were only observed in the low frequency intensity noise (<700 MHz). The high frequency intensity noise (>2 GHz) was observed to be independent of the grating current.<>     

硅锗脊型波导在中红外波段的连续光宽带波长转换

提出了一种基于硅锗(Ge-on-Si,GOS)的新型亚微米光波导,通过调节二阶色散对此波导的结构进行了优化设计,研究了其在波长为3~6μm间的连续光波长转换性能.数值结果表明,在脊宽2.8μm、脊高1.6μm,平板厚度0.48μm的优化结构下,当泵浦光波长在靠近二阶零色散点的负色散波长区时可以实现高转换效率宽带中红外波长转换,3 d B转换带宽可达到1664 nm,在0.05 GW/cm2的泵浦光功率密度下,最大转换效率可达到-2.479 d B.该波导在中红外波段具有波长转换带宽大、转换效率高的优点,在未来空间光子网络与通信方面具有潜在的应用前景.     

Temperature characteristics of wavelength tuning in separately pumped integrated-etalon interference lasers

We have characterised the temperature behaviour of the electronic wavelength-tunable separately pumped integrated etalon-interference laser operating at 0.9 ?m. The experimental results reveal two interesting features: the tuning bandwidth varies periodically as a function of temperature, and the possibility of single longitudinal mode operation within a wavelength-locking range ?T as large as 15 deg C.     

双波长半导体激光器Y形耦合波导模拟研究

提出了一种双DBR半导体激光器结构,该结构包括布拉格光栅、脊形波导、Y形波导、锥形放大器等部分,目标是实现半导体激光器双波长高功率、高光束质量的近红外激射.本文使用Rsoft BeamPROP模拟分析了Y形耦合波导的分叉角度对光传输的影响,确保双DBR脊形波导发射出的单模激光不互相干涉,使双波长单模激光在其中传输损耗最小.     

High-power operation in 0.98-μm strained-layer InGaAs-GaAssingle-quantum-well ridge waveguide lasers

High power strained-layer InGaAs-GaAs graded-index separate confinement heterostructure (GRIN-SCH) single-quantum-well (SQW) lasers at an emission wavelength of 0.98 μm have been fabricated. A light power as high as 270 mW and a maximum front power conversion efficiency of 51.5% have been obtained for the antireflective and highly-reflective coated laser with 9-μm-wide ridge and 600-μm-long cavity