λ=8.3 μm GaAs/AlAs quantum cascade lasers incorporatingInAs monolayers

The development of GaAs-based quantum cascade lasers incorporating indirect bandgap AlAs barriers in conjunction with ultrathin InAs layers in the active regions of the device is reported. The InAs layers produce a downshift of the energies of the lower lasing states, allowing laser emission to be observed at λ=8.34 μm. The GaAs/InAs/AlAs devices operate in pulsed mode up to a maximum temperature of 250 K, with a characteristic temperature of around 200 K for T>100 K     

Pulsed and continuous-wave operation of long wavelength infrared(λ=9.3 μm) quantum cascade lasers

The operation of quantum cascade lasers at a wavelength (λ≃9.3 μm) well within the 8-13-μm atmospheric window is reported. A detailed study of intersubband luminescence in a vertical transition structure shows linewidths as narrow as ~10 meV at cryogenic temperatures, increasing to 20 meV at room temperature. Pulsed operation is demonstrated up to 220 K with a peak power ≈10 mW and ≈35 mW at 140 K. The temperature dependence of the threshold current density (J _th) is described by a high T₀ (128 K), J_th is also systematically studied as a function of cavity length to determine the peak gain and waveguide losses. Continuous-wave, single-mode operation is demonstrated up to 30 K with powers ≈2 mW     

High-performance strain-compensated InGaAs-GaAsP-GaAs(λ=1.17 μm) quantum well diode lasers

This letter reports studies on highly strained and strain-compensated InGaAs quantum-well (QW) active diode lasers on GaAs substrates, fabricated by low-temperature (550°C) metal-organic chemical vapor deposition (MOCVD) growth. Strain compensation of the (compressively strained) InGaAs QW is investigated by using either InGaP (tensile-strained) cladding layer or GaAsP (tensile-strained) barrier layers. High-performance λ=1.165 μm laser emission is achieved from InGaAs-GaAsP strain-compensated QW laser structures, with threshold current densities of 65 A/cm² for 1500-μm-cavity devices and transparency current densities of 50 A/cm². The use of GaAsP-barrier layers are also shown to significantly improve the internal quantum efficiency of the highly strained InGaAs-active laser structure. As a result, external differential quantum efficiencies of 56% are achieved for 500-μm-cavity length diode lasers     

InAs0.97N0.03/InGaAs/InP multiple quantumwell lasers with emission wavelength λ=2.38 μm

Application of a novel InAsN alloy on a laser device is reported for the first time. The four-period InAs_0.97N_0.03-In_0.53Ga_0.47 As-InP strained multiple quantum well laser, grown by gas source molecular beam epitaxy with an RF-coupled plasma nitrogen source, lased under pulsed operation at 2.38 μm at 260 K. A threshold current density of 3.6 KA/cm² at 260 K and a characteristic temperature of 62 K have been achieved     

15 Gb/s multichannel optical interconnect laser array transmitteroperating at λ=1.3 μm

We have fabricated and measured detailed bit error rate experiments on a 12 channel optical interconnect transmitter operating at rates up to 1.25 Gb/s per channel, using InGaAsP/InP λ=1.3 μm lasers. The lasers are highly uniform, the channel crosstalk is less than 1 dB, and the mode selective losses are low (<1 dB). This transmitter has been demonstrated in an architecture which would allow the transmission of 120 channels of 100-Mb/s uncompressed video signals     

Strained-layer InGaAsP diode lasers with tapered gain region foroperation at λ=1.3 μm

A report is given of the first high-power InP-based tapered lasers. Continuous output powers of 0.5 W with nearly 80% of the power in the central lobe have been obtained. This is the highest reported brightness of a 1.3 μm source     

Optimization of Si1-xGex/Si waveguidephotodetectors operating at λ=1.3 μm

This paper analyzes the influence of various design parameters in the external quantum efficiency (QE) of waveguide detectors based on Si/Si_1-xGe_x strained-layer superlattices (SLSs), for use in optical communications at λ=1.3 μm. The study presents an algorithm that automatically generates structurally stable SLSs. This generation is completed by intensive simulation of the generated SLSs to calculate the external QE. The simulation embraces optical waveguiding, absorption, quantum size effect, as well as thermodynamics of the strained layers. Two sets of data were created using two different models for the SiGe layer critical thickness, h_c(x). A conservative model for h_c, corresponding to the equilibrium regime, yielded discrete maximum values for QE (around 12%) that were mainly dependent on the alloy absorption. A second model for h_c, corresponding to the metastable regime, produced considerably higher QEs (around 60%), and shows the great importance of fiber-to-waveguide coupling efficiency. The importance of the passive-waveguide coupler geometry is investigated using the beam propagation method     

Simultaneously at two wavelengths (5.0 and 7.5 μm) singlemodeand tunable quantum cascade distributed feedback lasers

Quantum cascade distributed feedback (QC-DFB) lasers based on a heterogeneous-cascade two-wavelength active waveguide core and a multisectioned cavity featuring two different Bragg gratings are demonstrated. Optimised lasers display singlemode emission at λ~5.0 and 7.5 μm simultaneously and a tunability on both modes equal to single-wavelength QC-DFB lasers     

1.5 μm λ/4 shifted multiple quantum well distributedfeedback laser diodes

1.5 μm λ/4 shifted multiple quantum well distributed feedback laser diodes have been achieved for the first time. A characteristic temperature value for a threshold current at around room temperature was as high as 88 K. Spectra at 0.9 times the threshold current showed substantial TM mode suppression. The MQW active region consists of four GaInAs wells (75 Å thick) and GaInAsP barriers (λ_g=1.15 μm, 150 Å thick) grown by metalorganic vapour phase epitaxy (MOVPE). 1.3 μm GaInAsP was grown as an optical guide layer     

2-Gbit/s signal amplification at λ=1.53 μm in anerbium-doped single-mode fiber amplifier

The gain, saturation power, and noise of an erbium-doped single-mode traveling-wave fiber amplifier operating at a wavelength λ=1.53 μm are characterized. In continuous-wave (CW) measurements amplification at 2 Gbit/s was demonstrated with up to 17-dB gain for 1×10^-9 bit error rate at 1.531 μm and a 3-dB full bandwidth of 14 nm. From the determination of the fiber-amplifier's output signal-to-noise ratio versus input signal power during data transmission, it was concluded that, with signal levels used here, signal-spontaneous beat noise limited the receiver sensitivity improvement. With the fiber amplifier acting as an optical preamplifier of the receiver, the best sensitivity was -30 dBm, obtained after installing a polarizer at the fiber amplifier output to reject half of the applied spontaneous emission power. This sensitivity was 6 dB better than without the fiber amplifier, proving that the fiber amplifier can be used as a preamplifier     

Germanium-diffused waveguides in silicon for λ=1.3 μm andλ=1.55 μm with losses below 0.5 dB/cm

The authors present a simple technique for the fabrication of integrated optical channel waveguides that are prepared by indiffusion of an E-beam evaporated amorphous alloy of germanium and silicon into commercially available silicon with low dopant concentration, using only simple technological processes such as standard lithography, PVD, and diffusion. The waveguides are polarization independent and have waveguide losses as low as 0.3 dB/cm at wavelengths of λ=1.3 μm and λ=1.55 μm. The spot sizes are well suited for low-loss single-mode fiber device coupling, being on the order of a few microns in both horizontal and vertical directions     

Coherent laser radar at 2 μm using solid-state lasers

The development of a coherent laser radar system using 2-μm Tm and Tm, Ho-doped solid-state lasers, which is useful for the remote range-resolved measurement of atmospheric winds, aerosol backscatter, and differential absorption lidar (DIAL) measurements of atmospheric water vapor and CO₂ concentrations, is described. Measurements made with the 2-μm coherent laser radar system, advances in the laser technology, and atmospheric propagation effects on 2-μm coherent lidar performance are discussed. Results include horizontal atmospheric wind measurements to >20 km. vertical wind measurements to >5 km, near-horizontal cloud returns to 100 km, and hard target (mountainside) returns from 145 km     

Low-temperature sensitive, compressively strained InGaAsP active(λ=0.78-0.85 μm) region diode lasers

This letter reports comparative studies between (Al)GaAs versus InGaAsP active region edge-emitting semiconductor lasers for emission wavelength in the IR regime (λ=0.78-0.85 μm). High characteristic temperature T₀(200 K) and T₁ (450 K) edge-emitting diode lasers have been demonstrated by using the compressively strained (Δa/a=0,6%) Al-free (InGaAsP) active region with an emission wavelength of 0.85 μm. The high T₀ and T ₁ a result of low active-layer carrier leakage, will be beneficial for high-temperature and high-power operation. Implementation for InGaAsP-active VCSEL's with compressively strained InGaAsP-active layers and conventional DBR's is also discussed     

法布里-珀罗腔在可调谐CO_2激光器中的应用

锐度较高的法布里-珀罗腔可以用来选择CO_2激光谱线,锐度较低的法布里-珀罗腔可以用来扩展可调谐CO_2激光器的谱线范围,并提高它的输出功率。本文分析了NaCl法布里-珀罗窗与管轴垂直使用的可调谐CO_2激光器的运转特性。     

双束可调频TEACO_2激光器

我们研制了一台双束可调频TEACO_2激光器,该器件除了具有能重复频率工作(重复频率大于10脉冲/秒)和有长工作寿命(一次充气可以连续工作10~6脉冲)的特点之外,还具有以下特点: 1.在同一增益介质内同步地进行两束激光振荡,每束都在9.2微米至10.9微米之间独立可调。     

InAs/GaInAs quantum dot DFB lasers emitting at 1.3 μm

Singlemode operation of 1.3 μm InAs/GaInAs quantum dot lasers has been achieved using the concept of complex coupled distributed feedback. Mode selection was realised by laterally patterned metal gratings. At room temperature the lasers show stable singlemode emission with sidemode suppression ratios of up to 55 dB, threshold currents as low as 17 mA and output powers of up to 8 mW under continuous wave operation     

All-fiber spectral filters with nonperiodic bandpasscharacteristics and high extinction ratios in the wavelength range 0.8μm<λ<1.6 μm

A simple modification is proposed to the dual-core spectral filter design which extends the range of single wavelength transmission considerably, making the filter characteristic nonperiodic in the wavelength range 0.8 μm<λ<1.6 μm. Also, a spectral filter based on collinear triple-core fiber is proposed which provides a substantially lower sidelobe level than the dual-core filter. Transmission characteristics of the proposed filters are calculated and compared with those of the unmodified dual-core filter. The advantages of the proposed filters, particularly for application in wavelength division multiplexed systems are addressed     

Dependence of high-speed properties on the number of quantum wellsin 1.55 μm InGaAs-InGaAsP MQW λ/4-shifted DFB lasers

The dependence of intrinsic dynamic properties, such as relaxation oscillation frequency, damping K-factor, and spectral chirping under 10-Gb/s direct modulation, on the number of quantum wells is systematically investigated in 1.55-μm multiquantum-well λ/4-shifted distributed-feedback lasers. The theoretical and experimental results indicate that the dependence of the above three factors on the number of quantum wells is clearly explained by the linear gain saturation of the quantum-well lasers     

Tunable laser pumped 3 μm Ho:YAlO3 laser

The tuning characteristics of the ⁵I₆ -⁵I₇ transition in a Ho:YAlO₃ laser, intracavity pumped by a 1.079 μm Nd:YalO₃ laser, were studied. Operation on seven distinct lines between 2.844 and 3.017 μm was found, and the threshold and relative slope efficiency of each line was measured. Several of these lines were previously unreported     

无氦重复频率长寿命可调谐TEA CO_2激光器

实验研究了无氦重复频率长寿命TEA CO_2激光器的输出特性,一次充气寿命大于10~6次脉冲,激光总效率为14％。实验表明,氦气对TEA CO_2激光器的输出特性影响不大。