Transfer-matrix dynamic model of partly gain-coupled 1.55 μm DFBlasers with a strained-layer MQW active grating

A dynamic model for partly gain-coupled 1.55 μm MQW DFB lasers consisting of etched strained-layer multiquantum wells is presented. For the modulation and noise characteristics of DFB lasers, analytical expressions which take into account both the longitudinal distribution of laser parameters and carrier transport effects are derived for the first time using the transfer-matrix method. As a numerical example, the relaxation oscillation frequency is compared to experimental results, and reasonable agreements are obtained between the theory and experiment     

20 Gbit/s, 1.55 μm strained-InGaAsP MQW modulator integrated DFBlaser module

The high-speed (20 Gbit/s) and highly efficient (2 V peak to peak for a 22 dB on/off ratio) operation of an MQW integrated electroabsorption modulator/DFB laser module is demonstrated. Output power from the module is over +3 dBm in the pigtailed singlemode fibre. To the authors' knowledge, this is the first report of 20 Gbit/s operation with a monolithically integrated light source     

Gigahertz self-pulsation in 1.5 μm wavelength multisection DFBlasers

Self-pulsation in InGaAsP/InP multisection distributed feedback (DFB) lasers was generated reproducibly by adjusting appropriate injection conditions. Frequencies of up to some gigahertz were achieved. It was demonstrated that-in contrast to Fabry-Perot (FP) elements-no selective treatment of one section is required for creating the self-pulsation. It is concluded that the self-pulsation in DFB elements is of a different type than in FP elements     

Low-noise single-photon detection at wavelength 1.55 μm

The photon-counting performance of commercially available InGaAs/InP avalanche photodiodes operated in Geiger mode was investigated at temperatures between 77 and 260 K. In particular, their noise equivalent power was measured to be 4×10^-17 WHz ^-1/2 at 77 K. The implications of these results in the context of a quantum cryptography application are discussed     

Reliability and degradation behavior of highly coherent 1.55 μmlong-cavity multiple quantum well (MQW) DFB lasers

Degradation behavior and reliability of 1.55 μm highly coherent MQW DFB laser with a long cavity are examined and clarified. The increase in spectral linewidth, due to the increase in 1/f noise and internal optical loss and the instability of the side mode, and the changes in FM response, especially the increase in FM efficiency, occur during degradation, e.g. increase in threshold current. In addition to these basic degradations, the degradation behavior of multisection DFB lasers is also clarified from the viewpoint of device characteristics, such as wavelength and tunability. By clarifying these changes in device characteristics, the possibility of long life for long-cavity MQW DFB lasers in optical coherent transmission systems is shown     

1.55μm多量子阱行波光放大器

介绍了1.55μm波段的多量子阱(MQW)行波式半导体激光放大器的制备及其特性的测量.其测量结果.在注入脉冲电流条件下.内增益为20dB.饱和输出峰值功率为40mW.     

Injection-locked 1.55 μm VCSELs with enhanced spur-free dynamicrange

Injection locking is demonstrated to improve the analogue performance of long wavelength VCSELs. The third-harmonic spur-free dynamic range was improved by 9 dB/Hz^2/3 to be 93 dB/Hz^2/3, and the modulation bandwidth was increased twofold     

1-mW CW-RT monolithic VCSEL at 1.55 μm

In this letter, we demonstrate the first result of a high-power (1 mW) continuous-wave room-temperature vertical-cavity surface-emitting laser emitting at 1.55 μm using a single InP substrate. The whole structure was grown monolithically using gas source molecular beam epitaxy and incorporates two original approaches. The first originality consists in the growth of a metamorphic GaAs-AlAs Bragg mirror directly on an InP-based cavity. The second novel idea is to use a tunnel junction for current injection. Moreover by using these two approaches the processing is very simple and, therefore, fulfills the goal for low-cost laser production in access and interconnections applications     

Analysis of the attenuation ratio of MQW optical intensitymodulator for 1.55 μm wavelength taking account of electron wavefunction leakage

A theoretical analysis of an attenuation ratio for MQW optical intensity modulator was carried out taking account of the leakage of electron envelope function from the well layer. In the MQW modulator using InGaAsP material, the leakage of electron envelope function is large even for a low applied field because of the comparatively low potential barrier for electron. A normalization scheme in energy space was introduced for such leaky envelope function and field dependence of the Stark shift and oscillator strength have been analyzed by solving exciton effective mass equation. This approach was applied to MQW modulator for the wavelength of 1.55 μm for optical communication system. The well width and well number for large attenuation ratio with small residual absorption have been obtained. The calculation was compared with the experimental result and the difference was discussed     

Very large arrays of flip-chip bonded 1.55 μm photodetectors

We present very large arrays of InGaAs-InP p-i-n photodetectors flip-chip bonded to Si. The photodiodes are designed for operation at zero bias, e.g., for spectroscopic applications. Our design maintains depletion at zero bias resulting in ~99% photocurrent collection efficiency. The series resistance of our photodiodes is <1 Ω for a 40×40 μm device, including the flip-chip bond, resulting in high tolerance to shunt leakage. We produce arrays of photodiodes as large as 120 and measure leakage currents. We analyze zero-bias photocurrent generation in the presence of leakage and determine that with this technology arrays as large as 128 can be produced with high yield. The concept of redundancy in zero-bias photodiode arrays is presented and explored. Under the assumption that photodiode leakage is produced by microscopic point defects, a substantial increase in uniformity can be achieved in photodetector arrays by employing redundancy     

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     

High-gain, high-power 1.3 μm compressive strained MQW opticalamplifier

A high-gain and high-saturation output power optical amplifier operating in the 1.3-μm wavelength region that was fabricated using a compressive-strained multiple-quantum-well active region is described. It is shown that optical gain as high as 27 dB and 3-dB saturation output power as high as 14 dBm were obtained simultaneously     

Polarization-insensitive superluminescent diode at 1.5 μm with atensile-strained-barrier MQW

Polarization-insensitive high-power superluminescent diodes emitting at 1.5-μm were fabricated by using a tensile-strained-barrier MQW. Polarization difference as low as 5% and 3.8 mW optical power were obtained at 200 mA injection current     

InGaAs-InAlAs quantum well intersecting waveguide switch operatingat 1.55 μm

The first electrooptic waveguide switch based on voltage-controlled transfer of electrons into multiple quantum wells is demonstrated. This mechanism is named barrier, reservoir, and quantum well electron transfer (BRAQWET) In GaAs-InAlAs quantum wells it provides a large modulation of refractive index at 1.55 μm with multigigahertz switching capability. The BRAQWET X-switch is free from heating and speed limitations associated with current injection. Beam propagation method (BPM) calculations suggest that the crosstalk performance of this preliminary device demonstration can be significantly enhanced by changes in waveguide geometry     

Pulsed 1.55 μm transmission mode microchip laser usingsemiconductor modulator

A semiconductor saturable absorber modulator is used, for the first time, in a passively Q-switched microchip laser in transmitting mode. The laser has a wavelength of 1.55 μm in a single longitudinal TEM₀₀ mode beam and has pulse characteristics that compare favourably with previously reported data on comparable devices     

Polarization-independent low-crosstalk polymeric AWG-based tunablefilter operating around 1.55 μm

A wavelength tunable optical filter is a beneficial optical component for dense wavelength-division-multiplexed systems. We report a high-performance polymeric arrayed-waveguide grating (AWG)-based tunable filter made of cross-linked silicone and operating around 1.55 μm. This filter exhibited a TE-TM polarization shift of <0.03, a crosstalk of <-35 dB, an insertion loss of <3 dB, and an 8.8-nm tuning range in the 25°C-75°C temperature region     

Predistortion of electroabsorption modulators for analog CATVsystems at 1.55 μm

A predistortion circuit with adjustable amounts of third- and fifth-order predistortion is studied both theoretically and experimentally. The circuit is used to cancel the third- and fifth-order intermodulation distortion of a 1.55-μm integrated electroabsorption modulator/DFB laser. The CSO obtained is -61 dBc and the CTB is reduced 22.6 dB to -65 dBc. This performance is maintained after fiber amplification and propagation through 13 km of nondispersion shifted fiber due to the modulator's low chirp. Dithering of the DFB laser's injection current is employed to increase the stimulated Brillouin scattering (SBS) threshold to +13.4 dBm     

1.55 mu m polarization-insensitive high-gain tensile-strained-barrier MQW optical amplifier

A polarization-insensitive semiconductor optical amplifier was realized at a wavelength of 1.55 mu m. The active layer consisted of a tensile-strained-barrier multiple quantum well (MQW) structure. At a driving current of 150 mA, no dependence of the saturation characteristics on modes was obtained. The saturation output power at which the gain decreases 3 dB is 13.3 dBm. A slightly higher saturation output power of 14 dBm was measured at a driving current of 200 mA. No large difference was observed between transverse-electric (TE) and transverse-magnetic (TM) modes. A high gain of 27.5 dB at a polarization sensitivity of 0.5 dB and a high saturation output of 14 dBm were realized simultaneously by using a longer device with reduced residual facet reflectivities.<>     

Very large bandwidth strained MQW DFB laser at 1.3 μm

A 3-dB bandwidth of 20 GHz has been demonstrated for a compressively strained multiquantum well InGaAsP-InP DPB laser operating at 1.3 μm. The laser displayed superior static performance including very low threshold current (~8 mA), high external quantum efficiency (0.44 mW/mA), high CW output power (>60 mW) and high temperature operation     

Fabrication of 1.55 μm VCSELs on Si using metallic bonding

Using AuGeNiCr multilayered metals as the wafer bonding medium, long-wavelength GaInAsP/InP vertical cavity surface emitting lasers employing Al-oxide/Si as the upper and lower distributed Bragg reflectors were fabricated on Si substrate with the bonding interface formed outside the vertical cavity surface emitting laser cavity. Laser emission at 1.545 μm was measured under pulsed operations near room temperature. The low-temperature metallic bonding process demonstrates a great potential in device fabrication