1.5 µm range InGaAsP/InP distributed feedback lasers

Lasing characteristics of InGaAsP/InP distributed feedback (DFB) lasers in the 1.5 μm range were studied theoretically and experimentally. Wave propagation in five-layer DFB waveguides were analyzed to estimate the effect of the structural parameters on threshold conditions. A brief consideration on designing a low threshold laser and its lasing wavelength was made. DFB buried heterostructure lasers with fundamental grating emitting at 1.53 μm were prepared by liquid phase epitaxial techniques. CW operation was confirmed in the temperature rangeof -20° to 58°C, and a CW threshold current was as low as 50 mA at room temperature. A stable single longitudinal mode operation was observed both in dc condition and in modulated condition by a pseudorandom pulse current at 500 Mbits/s. No significant increase in the threshold current was observed after 1400 h continuous CW operation at 20°C.     

Optimization of grating duty factor in gain-coupled DFB lasers withabsorptive grating-analysis and fabrication

Grating duty factor strongly affects the performance of gain-coupled (GC) distributed feedback (DFB) laser diodes with an absorptive grating. Through numerical analysis the authors have found an optimum value in the duty factor for their low threshold operation. The minimum threshold gain achievable at this optimum duty factor is found to be almost independent of the order of the grating. According to this prediction, the authors have fabricated GaAlAs/GaAs GC DFB lasers with a third-order absorptive grating where the grating duty factor has been made close to the theoretical optimum value. In 200-μm-long devices with both facets as-cleaved, low CW threshold current of 25 mA, external efficiency of 0.5 mW/mA, and SMSR as high as 45 dB have been obtained, which is qualitatively consistent with the analysis. High yield of single mode oscillation seems to be the result of the gain coupling     

1.78 μm应变InGaAs-InGaAsP-InP分布反馈量子阱激光器

采用低金属有机汽相外延(LP-MOVPE)生长大应变InGaAs/InGaAsP做有源区,研制了激射波长为1.78μm的脊波导分布反馈(DFB)激光器,对于解理腔长为900μm的激光器,室温时其激射的阈值电流为33mA,最大单面光输出功率/和单面外微分量子效率分别为8mW和7％;此外,激射光谱边模抑制比(SMSR)为27.5dB。     

选择外延MOCVD研制DFB激光器和模斑转换器集成器件

研究了利用选择外延生长的InGaAsP材料的厚度增强因子和带隙波长的性质,最大的厚度增强因子为2.9.利用选择外延技术研制的DFB激光器和模斑转换器的集成器件,阈值为10.8mA-在60mA下输出功率为10mW,边模抑制比为35.8dB,垂直方向上的远场发散角从34°减少到9°,垂直方向上的1dB偏调容差为3.4μm.     

选择外延MOCVD研制DFB激光器和模斑转换器集成器件

研究了利用选择外延生长的InGaAsP材料的厚度增强因子和带隙波长的性质,最大的厚度增强因子为2.9.利用选择外延技术研制的DFB激光器和模斑转换器的集成器件,阈值为10.8mA-在60mA下输出功率为10mW,边模抑制比为35.8dB,垂直方向上的远场发散角从34°减少到9°,垂直方向上的1dB偏调容差为3.4μm.     

Dynamic and CW linewidth measurements of 1.55-μm InGaAs-InGaAsPmultiquantum well distributed feedback lasers

Measurement of the CW linewidth and frequency chirp as functions of modulation data rate and bias level for 1.55-μm InGaAsP multiquantum-well distributed feedback lasers grown by low-pressure MOCVD are presented. The results show that the CW linewidth of asymmetric facet-coated multiquantum-well DFB lasers can be as low as 2.0 MHz at 13.5 mW output power. The frequency chirp increases with modulation data rate and is significantly larger if the laser off-state is below threshold than if it is above threshold. The 20 dB down chirp widths are in the range of 1.9-5 Å for 40 mA peak-to-peak modulation current at 10 Gb/s under above-threshold bias     

Distributed feedback quantum cascade lasers operating in continuous-wave mode at λ≈7.6μm

正Distributed feedback(DFB) quantum cascade lasers(QCLs) in continuous-wave(CW) mode emitting atλ≈7.6μm are presented.Holographic lithography was used to fabricate the first-order distributed feedback grating. For a high-reflectivity-coated QCL with 14.5-μm-wide and 3-mm-long cavity,CW output powers of 300 mW at 85 K and still 10 mW at 270 K are obtained.Single-mode emission with a side-mode suppression ratio(SMSR) of about 30 dB and a wide tuning range of ~300 nm in the temperature range from 85 to 280 K is observed.     

Low threshold operation of 1.5-µm DFB laser diodes

Highly reliable distributed feedback (DFB) laser diodes operating at 1.5-μm wavelength range are fabricated through optimizing the device parameters. Thickness control of the active layer is found to be an essential factor in achieving low threshold operation of DFB lasers. The threshold current as low as 11 mA and stable single longitudinal mode CW operation up to 106°C is achieved with these DFB lasers.     

Very-low-threshold, highly efficient, and low-chirp 1.55-/spl mu/m complex-coupled DFB lasers with a current-blocking grating

Low-threshold current DFB lasers have been fabricated based on a complex-coupled structure with a current blocking grating. A threshold current as low as 5 mA was obtained, which enabled high temperature operation up to 105/spl deg/C. Asymmetric facet coatings were applied to obtain a high efficiency of 0.3 W/A. The strained InGaAsP MQW active region and the antiphase coupling has resulted in a low modulation chirping. By direct modulation of the device at 2.488 Gb/s and using optical amplifiers, we have demonstrated digital transmission over a 235 km-long standard single-mode fiber with a power penalty of 1.55 dB.     

High-speed, low-threshold InGaAsP semi-insulating buried crescentlasers with 22 GHz bandwidth

The authors have fabricated high-speed, low-threshold 1.3 μm InGaAsP semi-insulating buried crescent lasers with a CW 3 dB modulation bandwidth of 22 GHz and a threshold current as low as 6.5 mA at room temperature. This is the highest 3 dB modulation bandwidth ever reported for the planar-type semiconductor laser. These results were achieved by implementing a submicron photolithographic process in the channel etching to reduce the cavity width and a polyimide dielectric layer under the bonding pad area to minimize the electrical parasitics     

InGaAs-GaAs-InGaP distributed feedback buried heterostructurestrained quantum-well lasers for high-power operation at 0.98 μm

Data are presented on device results from InGaAs-GaAs distributed feedback buried heterostructure (DFB BH) strained-quantum-well lasers with InGaP cladding layers. DFB BH lasers with a p-n InGaP current blocking junction entirely grown by a three-step MOVPE on GaAs substrates show a low laser threshold of 3.2 mA and a high output power of 41 mW with single-longitudinal-mode operation, both measured CW at RT. The monomode oscillation is obtained even at the injection current of 140 mA (44 times the laser threshold) with the side-mode suppression ratio of 35 dB and the temperature sensitivity of Bragg modes being 0.5 Å/°C measured between 20 and 40°C     

Low dispersion penalty and wide temperature range operation over120 K with 1.55 μm strained MQW-DFB laser module

STM 16 (2.488 Gbit/s) system operation over a wide DFB chip temperature range of more than 120 K (from -25°C to +95°C) is presented with dispersion penalty below 1 dB after transmission across 100 km standard fibre. DFB operation at 1.55 μm with a high sidemode suppression ratio of 40 dB is achieved within -40°C to +95°C. The lasers were realised using a BRS lateral structure and a quaternary InGaAsP MQW stack with six compressively strained quantum wells and a highly detuned DFB grating     

InAs-InAlGaAs quantum dot DFB lasers based on InP [001]

The InAs-InAlGaAs quantum dot (QD) lasers with the InAlGaAs-InAlAs material system were fabricated on distributed feedback (DFB) grating structures on InP [001]. The single-mode operation of InAs-InAlGaAs QD DFB lasers in continuous-wave mode was successfully achieved at the emission wavelength of 1.564 /spl mu/m at room temperature. This is the first observation on the InP-based QD lasers operating around the emission wavelength window of 1.55 /spl mu/m. The threshold current density of the InAs-InAlGaAs QD DFB laser with a cavity length of 1 mm and a ridge width of 3 /spl mu/m, in which one of the cleaved facets was coated with 95% high-reflection, was 1.23 kA/cm/sup 2/ (176 A/cm/sup 2/ for single QD layer). The sidemode suppression ratio value of the QD DFB laser was as high as 42 dB at the driving current of 100 mA.     

Low-threshold-current distributed-feedback InGaAsP/InP CW lasers

Distributed-feedback buried-heterostructure InGaAsP/InP lasers with room temperature CW threshold current as low as 50 mA, corresponding to a current density of 2.3 kA/cm2, are presented. CW operation in the temperature range from ?20°C to 58°C was confirmed.     

GaInAsSb-AlGaAsSb distributed feedback lasers emitting near 2.4 /spl mu/m

We have investigated fabrication and characteristics of continuous wave (cw) GaInAsSb-AlGaAsSb distributed feedback (DFB) lasers in the 2.4-/spl mu/m range. Single-mode DFB emission is obtained without overgrowth by first order Cr-Bragg gratings on both sides of a laser ridge. The cw threshold currents for a cavity with a length of 800 /spl mu/m and a width of 4 /spl mu/m are around 30 mA. At 20/spl deg/C and at an injection current of 190 mA output powers of 8.5 mW were realized. Monomode emission with a side-mode suppression ratio (SMSR) of 33 dB has been obtained.     

InGaAsP/InP separated multiclad layer stripe geometry lasers emitting at 1.5 ?m

InGaAsP/InP separated multiclad layer stripe geometry lasers emitting at 1.5 ?m are reported. The CW threshold current at 25°C is only 82 mA and the maximum temperature where CW lasing is obtained is 65°C. The characteristic temperature of the pulsed threshold current is 60 K. The transverse mode is fundamental and the longitudinal mode is single up to 1.5 times the threshold under CW operation. A few samples operated for over 1000 h at 50°C under constant optical power operation of 5 mW/facet.     

Effect of p-contact metallization on the performance ofgain-coupled DFBs with oxide-defined surface gratings

The effect of p-contact metallization on the performance of a single-growth-step ridge waveguide InGaAs-GaAs distributed feedback (DFB) laser with a silicon dioxide defined titanium surface grating is analyzed. The metallic surface grating introduces a periodic variation of the loss in the cavity to promote single-frequency emission. Device characteristics for DFBs with 50, 150, and 300 Å of titanium are compared. Under continuous-wave (CW) conditions, the devices with a titanium adhesion layer of only 50 Å operate on single-longitudinal and single-lateral modes, with threshold currents of roughly 14 mA, slope efficiencies of 0.16 W/A and sidemode suppression ratios (SMSRs) of greater than 40 dB     

1.55 ?m InGaAsP low-threshold buried-crescent injection laser

Fabrication of 1.55 ?m InGaAsP buried-crescent (BC) injection lasers with a p-n-p-n blocking structure is described. The BC lasers exhibit a threshold current as low as 14 mA at 25°C, very high yield, output power more than 10 mW and high-temperature operation up to 80°C. These BC lasers have continued to operate in stable CW mode at 50°C for more than 1000 h. The lifetime of the 1.55 ?m InGaAsP lasers at 50°C is estimated to exceed about 2.5 × 104 h.     

High-Reliable and High-Speed 1.3 μm Complex-Coupled Distributed Feedback Buried-Heterostructure Laser Diodes With Fe-Doped InGaAsP/InP Hybrid Grating Layers Grown by MOCVD

In this paper, we report the fabrication of high-reliability and high-speed 1.3 mum complex-coupled distributed feedback (CC-DFB) buried heterostructure (BH) laser diodes (LDs) with Fe-doped InGaAsP/InP hybrid grating layers. High optical coupling coefficient and eminent current confining ability are accomplished by combining the Fe-doped InGaAsP/InP current-blocking-grating (CBG) layers to provide both the distributed-feedback index-and gain-coupling coefficients. Besides, the narrow-stripe BH LDs are implemented by burying the active region with a Fe-doped InP current-blocking layer during the epitaxial regrowth. The fabricated CBG CC-DFB BH LDs at 20degC shows a low threshold current of 5.3 mA, a maximum light output power of 36 mW at 100 mA, a high slope efficiency of 0.41 mW/mA, and a side-mode suppression ratio (SMSR) of 42 dB at twice the threshold. In addition, these LDs exhibit a maximum operation temperature of 125degC, an extremely low threshold current of 15.8 mA at 90degC, a small variation in slope efficient of only -1 dB in the temperature range from 20degC to 80degC, and a characteristic temperature of 77 K and 56 K between 20 degC and 60degC, and 70degC and 120degC, respectively. Furthermore, these 1.3 mum CBG CC-DFB BH LDs exhibit a high-speed characteristic up to 11.8 GHz at room temperature and an estimated median lifetime of more than 1.1 times 10⁵ h or 12.5 years at 5 mW and 85degC.     

Entirely VPE-grown 1-5?m DFB lasers with low threshold currents

Entirely hydride VPE-grown 1.5?m DFB lasers have been obtained by means of high controllability in film thickness and alloy composition for the GalnAsP/InP system. A low threshold current of 13 mA was achieved by improving the growth method for the layer burying the grating. High uniformity in threshold current and lasing wavelength (Ith = 27.3 ± 9.7 mA, ? = 15571 ± 12?) was obtained.