A CW external-cavity surface-emitting laser

Room temperature, continuous wave (CW) operation of an external-cavity, optically-pumped surface-emitting laser is reported. The device is a resonant-periodic gain (RPG) vertical-cavity surface-emitting laser (VCSEL) with the top mirror stack replaced by an epitaxially grown antireflection (AR) coating. An external mirror having a 50-mm radius of curvature completes the resonator in a near hemispherical configuration. Mode spectra, input-output curves, and polarization properties of the device are presented.     

Vertical external-cavity surface-emitting laser for dual-wavelength generation

We report an optically pumped vertical external-cavity surface-emitting laser that is designed for emission at two wavelengths simultaneously. Single transverse mode continuous-wave (CW) operation is demonstrated at the wavelengths of 984 and 1042 nm. The device produces a CW optical power of 140 mW for the 984-nm component and 115 mW for the 1042-nm component, exhibiting over 10% efficiency. At a high pump power, self-pulsation of the components appeared on top of the CW-mode components. The maximum total output of 1 W was obtained at the pump power of 9 W.     

Diamond-microchip GaInNAs vertical external-cavity surface-emitting laser operating CW at 1315 nm

What is believed to be the first microchip-format vertical external-cavity surface-emitting laser (VECSEL) operating at 1.3 /spl mu/m is reported. Fundamental-mode continuous-wave output powers >120 mW were achieved from a cavity volume /spl sim/0.001 mm/sup 3/ using a diode-pumped GaInNAs VECSEL structure capillary-bonded to a dielectric-mirror-coated single-crystal diamond heatspreader.     

Dual-mode semiconductor-optical-amplifier external-cavity laser

A dual-mode semiconductor-optical-amplifier external-cavity laser is presented. The dual-mode optical output can produce a radio frequency beat signal at 31.6 GHz with a 3 dB linewidth of 700 kHz.     

Fast frequency-tunable external-cavity laser

We describe a tunable, single-frequency, narrow-line external-cavity laser that can be FSK up to 100Mbit/s by modulating the laser current. The result is obtained by using a two-section laser: one section for lasing and the other for FSK modulation.     

Electronically tunable external-cavity semiconductor laser

The authors have demonstrated electronic tunability of 35 nm in an external cavity GaAs semiconductor laser by using an acousto-optic (AO) tunable filter and an AO modulator inside the cavity. Tuning is accomplished by varying only the drive frequency of the AO devices     

24 h frequency stabilisation of an SLM external-cavity semiconductor laser

Long-term single-frequency stabilisation of an external-cavity semiconductor laser has been demonstrated using a multisegment composite-cavity configuration and an automatic frequency control loop with feedback to the external cavity. Mode-hopping free single-longitudinal-mode oscillation with a linewidth of about 200 kHz and a frequency shift within 28 MHz has been observed over 24 h.     

MEMS型可调外腔激光器的研究

文章提出了一种以MEMS TOF(微电子机械系统可调光滤波器)和标准具作为波长选择元件,LC(液晶)作为相位补偿元件,平面反射镜提供光反馈的可调外腔半导体激光器结构。实际研制了该结构的激光器样品,实验测得该激光器的输出功率>10dBm,边模抑制比>50dB,可调谐范围达到7nm,线宽约为200kHz。     

Tunnel injection active region in an oxide-confined vertical-cavity surface-emitting laser

Data are presented on oxide-confined AlGaAs-GaAs-InGaAs VCSEL's that use high-index half-wave GaAs spacer layers and electronic tunnel injection and confinement. To our knowledge, this is the first demonstration of tunnel injection in a vertical-cavity laser. Threshold currents range from 344 /spl mu/A for a 6.5-/spl mu/m diameter device to 151 /spl mu/A for a 1-/spl mu/m diameter device. The relatively high threshold currents are attributed to a detuned cavity and higher order transverse-mode operation.     

Single-mode operation from an external cavity controlledvertical-cavity surface-emitting laser

Single-mode operation from an index-guided vertical-cavity surface-emitting laser (VCSEL) has been achieved by using a fiber Bragg grating (FBG) as an external selective wavelength reflector. The spectral characteristics of the external cavity controlled VCSEL under static and dynamic conditions have been studied. The FBG provided stable single mode operation under pseudorandom modulation with a sidemode suppression ratio of ~30 dB from 500 Mb/s up to 4 Gb/s at room temperature     

High-power vertical-cavity surface-emitting laser with an extra Au layer

We report the performance of a high-power vertical-cavity surface-emitting laser (VCSEL) with an extra Au layer. By using the extra Au layer, the far-field divergence angle from a 600-/spl mu/m diameter VCSEL device is suppressed from 30/spl deg/ to 15/spl deg/, and no strong sidelobe is observed in far-field pattern. There is a slight drop in optical output power due to the introduction of the extra Au layer. By improving the device packaging method, the VCSEL device produces the maximum continuous-wave optical output power of 1.95 W with lasing wavelength of 981.5 nm. The aging test is carried out under constant current mode at 60/spl deg/C, and the preliminary result shows that the total degradation of output power is less than 10% after 800 h.     

Regimes of chaotic synchronization in external-cavity laser diodes

Chaotic synchronization is investigated experimentally using two diode lasers as transmitter and receiver. The transmitter laser is rendered chaotic by application of an optical feedback in an external-cavity configuration. Experimental conditions are found under which the synchronization diagram makes a transition from a positive to a negative gradient. A regime of operating conditions is identified in which the receiver laser is found to anticipate the dynamics of the transmitter laser. The anticipation time does not depend on the external-cavity length, but rather on the time of flight between the two lasers. Changes in the spectrum of the synchronized system are shown to be associated with the transition between anticipating and lag synchronization.     

Ultralow-threshold cryogenic vertical-cavity surface-emitting laser

Data are presented characterizing a low-threshold vertical-cavity surface-emitting laser designed for cryogenic operation. A threshold current of 12 μA and current density of 25 A/cm² are obtained at 77 K with the low-loss cavity design. From 77 K to 160 K, the threshold increases linearly with temperature, but only approximately tracks the detuning of the cavity resonance from the minimum energy transition of the quantum well. At 77 K, we estimate that the 25-A/cm² threshold current density is about twice that required for transparency     

Vertical cavity surface-emitting laser with an AlGaAs/AlAs Braggreflector

The letter elucidates the room temperature pulsed operation of a vertical cavity surface-emitting laser with an electrically conductive AlGaAs/AlAs distributed Bragg reflector (DBR). The maximum reflectivity of a DBR grown by MOCVD was 96% at 0.88 μm wavelength. The threshold current of 30 μm diameter devices was 200 mA under room temperature pulsed condition, which is the lowest value for such a broad area structure     

Three-terminal dual-stage vertical-cavity surface-emitting laser

A three-terminal dual-stage VCSEL, operating continuous-wave at room temperature has been fabricated. Independent biasing of the two active stages leads to an extended singlemode regime compared to conventional VCSELs. The parallel configuration reveals singlemode operation with a differential series resistance <35 Ω     

Hybrid-integrated external-cavity laser without temperature-dependent mode hopping

We propose and demonstrate an integrated external-cavity laser (ECL) with a novel configuration designed to suppress temperature-dependent mode hopping. The laser cavity is composed of a spot-size converter integrated laser diode (SS-LD), a UV-written grating, and silicone-filled grooves on a planar lightwave circuit (PLC). The silicone is used to compensate for the difference between the temperature coefficients of the SS-LD and the silica waveguides. We calculate theoretically the temperature interval of the mode hopping in the ECL to optimize the length of the silicone-filled grooves. We fabricated test and practical lasers with the proposed configuration using PLC hybrid-integration technologies. With the test laser, we confirmed stable single-mode oscillation and a large increase in the mode-hopping temperature interval for both static and dynamic operation. We obtained a low threshold of 15 mA, an optical power of 1.0 mW at 25/spl deg/C, and an injection current of 60 mA. In the practical laser, which we additionally integrated with a front monitor photodiode, we realized auto power control with mode-hopping-free operation from 18/spl deg/C to 56/spl deg/C. These results indicate the good performance levels of our proposed laser.     

Proposal of electrically tunable external-cavity laser diode

We propose and demonstrate a novel tunable external-cavity laser diode that simultaneously achieves rapid tuning rate and wide tuning range by electrical control. This contains new-type integrated laser diode, collimating lens, and diffraction grating mirror. The integrated laser diode consists of Fabry-Pe/spl acute/rot laser diode and waveguide-type deflector, which can deflect the beam passing through the waveguide. By control of the current in the deflector region, maximum wavelength variation of 8.6 nm and sidemode suppression ratio of >35 dB were obtained.     

Chaotic self-pulsation and cross-modulation in awavelength-selective external-cavity laser diode

Chaotic self-pulsation in a single wavelength external-cavity laser diode is observed. It is shown that the self-pulsation is caused by interdependencies between the optical output power and the compound cavity losses through the refractive index of the laser diode material. Refractive index changes result in a detuning between the externally selected wavelength and the weak internal-mode structure of the anti-reflection coated laser diode. This detuning is directly related to the compound cavity losses. On the one hand, a change in optical output power results in a change of the refractive index via the carrier density. On the other hand, it results in a change of refractive index via temperature changes. Compared to the carrier induced refractive index change, the temperature induced refractive index change is opposite in sign, a factor of ~10² smaller and slower. The switch-on and switch-off time of the self-pulsation is governed by the carrier life time. The repetition rate of the self-pulsation is governed by the thermal time constant and is in the megahertz region. Cross-modulation resulting from the thermal induced refractive index change is demonstrated. In a two-wavelength double external-cavity laser diode, optical power at one wavelength effects the optical power at the other wavelength. This cross-modulation is shown to be related to previous experiments on a laser neural network. A novel technique is introduced to measure the thermal impedance of a laser diode that is based on the cross-modulation     

Modeling temperature effects and spatial hole burning to optimizevertical-cavity surface-emitting laser performance

Two-dimensional physical models for single-mode index guided vertical cavity surface emitting lasers (VCSELs) are developed and compared with experimental measurements on state-of-the-art devices. Starting with the steady-state electron and photon rate equations, the model calculates the above threshold light-current (LI) characteristics. Included are temperature effects, spatial hole burning effects, carrier diffusion, surface recombination, and an estimation of optical losses. The model shows that the saturation of output power in the experimental devices is due to carrier leakage over the heterojunction and not simply the shifting of the gain peak relative to the cavity mode. Using the verified model new designs are analyzed, showing that output powers greater than 15 mW and power efficiencies above 20% should be achievable with existing processing technology     

Measurement of the working parameters of an air-post vertical-cavity surface-emitting laser

We present a complete experimental evaluation of the effective parameters necessary to describe the dynamical behavior of an air-post vertical-cavity surface-emitting lasers, on the basis of theoretical equations which are also derived in this paper. The experimental investigation is composed of several steps, including power versus current measurement, noise spectrum analysis, linewidth evaluation. The complete set of parameters derived, in particular the linewidth-enhancement factor and the spontaneous emission factor, is particularly important for accurate comparisons of theoretical models on the laser dynamics with experiments.