Tunable dual-wavelength all-PM fiber ring laser

A multisegment all-PM fiber ring laser is constructed to demonstrate a tunable dual-wavelength laser source with continuous tuning in absolute wavelength and discrete tuning in wavelength spacing. The tuning method is based on birefringence filtering properties of a segmented all-PM fiber ring resonator. Using this method, we show a discrete wavelength spacing of dual-wavelength output from 0.9 to 2.5 nm, and continuous wavelength tuning over a few nanometers. The demonstrated dual-wavelength laser can be easily modified to tune over a greater wavelength spacing and absolute wavelength range     

1.5 μm two-section Fabry-Perot wavelength tunable optical filter

A 1.5 μm two-section Fabry-Perot wavelength tunable optical filter is studied. As opposed to DFB filters, this wavelength tunable optical filter has the advantage that the wavelength tuning range and the transmission bandwidth can be designed independently. This two-section Fabry-Perot filter also controls the transmissivity (gain) and the transmission wavelength independently by current injection and the constant-gain and constant-bandwidth wavelength tuning is achieved. The wavelength tuning range is as wide as 188 GHz (15 Å), the constant-gain is as high as 23 dB and the constant-bandwidth is as narrow as 5 GHz during wavelength tuning. A 25-channel wavelength selection with less than -10 dB crosstalk is expected with this filter     

Mode-hop-free wavelength-tunable distributed Bragg reflector laser

Mode-hop-free wavelength tuning of 4.45 nm was achieved by a short-active-region distributed Bragg reflector laser without phase control. Simple and continuous tuning was realised with a single tuning current. High-speed wavelength tuning of 5 ns during direct modulation of 2.5 Gbit/s was also achieved.     

Wavelength tuning of GaInAsP/InP integrated laser with butt-jointed built-in distributed Bragg reflector

Fine tuning of lasing wavelength was achieved with a butt-jointed built-in DBR laser integrated with an additional tuning waveguide. The plasma effect of the injected carrier was utilised. The wavelength shift of 4.0 ? was demonstrated by an injected tuning current of 4.1 mA.     

A tunable distributed amplification DFB laser diode (TDA-DFB-LD)

A novel wavelength-tunable distributed amplification distributed feedback laser diode (TDA-DFB-LD) is proposed and fabricated. The proposed structure provides synchronous change between the longitudinal mode and the Bragg wavelength in tuning; thereby continuous wavelength tuning can be realized with single control-current. Moreover, extended tuning is also possible with two control-currents. A continuous tuning range of 2.9 nm and an extended discrete tuning range of 15 nm are experimentally obtained with a 1.55-μm TDA-DFB-LD     

Design and fabrication of GaAs-GaAlAs micromachined tunable filter with thermal strain control

In this paper, we present the design and fabrication of a novel GaAlAs-GaAs micromachined vertical cavity filter with a thermal strain control layer for wide wavelength tuning. The integration of a thermal strain control layer and heating element enables wavelength tuning induced by heating. The proposed tunable filter under thermal tuning operation provides us large tuning range over conventional micromachined tunable filters using electrostatic force. The calculated result shows a possibility of large continuous tuning range of over 100 nm. We fabricated a micromachined GaAlAs-GaAs vertical cavity filter with a strain control layer. The temperature dependence of the filter can be freely controlled either with temperature insensitive operation or with an enhanced temperature dependence, which depends on the thickness of the thermal strain control layer. We demonstrate a thermal wavelength tuning of 53 nm with a low tuning voltage of 6.1 V for the first time.     

光纤光栅外腔半导体激光器频率调谐技术研究

在分析了光纤光栅外腔半导体激光器(FBG-ECL)基本特性的基础上,调研了适用于该类型激光器的频率调谐方法,包括温度调谐法和应力调谐法,选取轴向应力调谐法改变光纤光栅的布拉格中心波长,进而实现频率调谐。利用压电陶瓷(PZT)来对光纤光栅施加轴向应力,通过调整PZT驱动电压值的大小来控制光纤光栅布拉格中心波长的变化量。实验结果表明,对于波长1550 nm的光纤光栅激光器,当PZT的驱动电压增加到126 V时,可实现 0.8 nm,即100 GHz的调谐范围以及每周期2 ms的调谐速度。     

一种新型光纤光栅波长与带宽独立调谐的方法

提出了一种新型的光纤光栅的中心波长与带宽独立调谐的方法。将光纤布拉格光栅(FBG)粘贴于圆环形薄壁截面梁的外表面,通过旋转圆环形薄壁截面梁,即相当于改变光纤光栅的位置来实现中心波长与带宽的独立调谐。实验上得到了6.706 nm准无啁啾的中心波长调谐和5.368 nm的准无中心波长漂移的最大带宽调谐,并且此中心波长和带宽调谐均与拉力呈线性关系,实验结果与理论分析一致。     

1.5 μm phase-controlled distributed feedback wavelength tunableoptical filter

A 1.5-μm phase-controlled distributed feedback wavelength-tunable optical filter is studied. This is the first optical filter which controls the transmissivity (gain) and the transmission wavelength independently. Wavelength tuning range as wide as 43 GHz (3.4 Å) with high constant gain of 27 dB has been achieved. A five-channel wavelength selection with less than -10 dB crosstalk is expected with this filter. This device also operates as a wavelength tunable laser, and the wavelength tuning range as a laser is larger than as a filter. The reason is studied, and it is shown that suppression of the submodes is important to expand the wavelength tuning range     

Wavelength tuning mechanism in three-electrode DFB lasers

The wavelength tuning mechanism is investigated for three-electrode distributed feedback (DFB) InGaAs-InGaAsP lasers. It is shown that the side and center sections play different roles in wavelength tuning: the former determines the effective Bragg wavelength and the latter contributes through the round-trip phase condition. The lasing wavelength is expressed in a simple form that renders the wavelength shift behavior exceedingly understandable. The indispensability of the thermal contribution to continuous broad range tuning is also clarified both theoretically and experimentally     

参考谱线法测量倍频Nd:YAG激光器调谐波长的研究

为了精确测量倍频Nd:YAG激光器的调谐波长,采用碘分子在532nm附近的强吸收谱线作为频率稳定的绝对参考谱线,建立了以碘蒸气为标定物的激光调谐波长测定系统,实际测量了碘蒸气吸收谱线.通过谱线的特征结构与理论吸收谱线的比较,得到了倍频Nd:YAG激光器调谐频率与外加偏压及电位计旋转角度的对应关系,并确定了激光频率跳变点的位置,最后给出了倍频Nd:YAG激光器的调谐范围.结果表明,碘吸收谱线法可以用来精确测量倍频Nd:YAG激光器的调谐波长.     

1.5-μm wavelength tunable phase-shift-controlled distributedfeedback laser

A 1.5 μm wavelength tunable phase-shift-controlled distributed feedback laser diode is studied. This wavelength tunable laser controls the light output power and the oscillation wavelength independently by current injection. During wavelength tuning, the submode suppression ratio is large and an almost constant spectral linewidth from 24 to 29 MHz is achieved over a wavelength tuning range as wide as 113 GHz (9.0 Å). The threshold gain change and the loss change are small during wavelength tuning and as a result an almost constant light output power is achieved     

波长调谐随机移相算法的研究

波长移相干涉仪可用于大口径光学元件的测试。其移相量需经过标定方可采用定步长移相算法计算相位分布。在长腔长测试条件下,由于激光器的波长调谐控制电源的精度有限,以及环境振动、气流扰动等的影响,采用定步长移相算法求解相位分布的精度不高。在随机移相算法的基础上,提出了波长调谐随机移相算法,并将其应用于大口径波长移相干涉仪中。在对该算法进行模拟仿真,验证了算法的可行性及精度后,进行了实验研究。实验结果表明,在波长移相干涉仪中运用该方法,可以很好地解决长腔长测试条件下的相位计算问题,且与被测件的理想相位比较,精度较高。     

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     

Wide range wavelength tuning in 1.3 ?m DBR-DC-PBH-LDs by current injection into the DBR region

Wide range wavelength tuning by controlling the Bragg wavelength electrically was demonstrated for the first time in a newly developed 1.3 ?m distributed Bragg reflector double channel planar buried heterostructure laser diode (DBR-DC-PBH LD). Lasing wavelength was tuned over 40 ? with 60 mA tuning current change, maintaining single longitudinal mode (SLM).     

Anomalous tuning of single mode AlGaAs diode lasers

Deviations from the normal tuning of a TJS AlGaAs diode laser have been observed. In the usual situation, the emitted wavelength of a single mode diode laser as a function of temperature is described by a "staircase" function, that is, the tuning curve consists of regions of smoothly increasing wavelength as a function of temperature separated by positive wavelength mode hops. We have observed a tuning curve for which the regions of smooth temperature tuning are separated by negative wavelength mode hops. It is suggested that this effect is due to the existence of structure in the laser's effective gain curve.     

1.5 μm phase-shift-controlled distributed feedback wavelengthtunable optical filter

A 1.5-μm phase-shift-controlled distributed feedback wavelength tunable optical filter is studied. This wavelength tunable optical filter controls the transmissivity (gain) and the transmission wavelength independently by current injection. During wavelength tuning, the submode suppression ratio is large and a wavelength tuning range as wide as 120 GHz (9.5 Å) with 24.5-dB constant gain is achieved. An 18-channel wavelength selection with less than -10 dB crosstalk is expected with this filter. The effect of the light input, whose wavelength is in the sidelobe, on the transmission spectrum shape is shown     

Sampled grating tunable twin-guide laser diodes with over 40-nm electronic tuning range

Device and tuning characteristics of sampled grating tunable twin-guide laser diodes are presented. The vertically integrated, monolithic widely tunable laser requires only two tuning currents to fully cover a wavelength range of more than 40 nm by electrooptic tuning. Its tuning behavior is quasi-continuous with up to 8.2-nm broad continuous tuning regions. High sidemode suppression (SMSR /spl ges/ 35 dB) as well as large output power (P /spl ges/ 10 mW) are obtained over the wavelength range from 1520.5 to 1561.5 nm.     

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