Cavity Surface-emitting Laser Research Articles

High minority carrier mobility and electronic diffusion length in annealed GaInAsSb/GaSb active layer in Vertical Cavity Surface Emitting Laser (VCSEL)

Owing to its important role as an active layer for Vertical Cavity Surface Emitting laser (VCSEL). We studied the transport properties in annealed GaInAsSb /GaSb by means of PTD technique. We remark that annealing time improve significantly the diffusion length and minority carrier mobility. For an annealed time duration of 60 min the diffusion length reach 25 µm (3.9%) and the minority carrier mobility reach 3673 cm2/V. (3.4%).We have observed that surface recombination velocity (SRV) decreased in respect of annealing time and was found to be 1450 m / s (± 3.6). Unfortunately, interface recombination velocity (IRV) is highly increased from 1196 m / s (± 5) to 6000 m/s (5%) for GaInAsSb as grown to that annealed during 60 min.

Microscopic modeling of non-normal incidence vertical external cavity surface-emitting laser cavities

The optimization of a V-cavity geometry to obtain intense ultrafast pulses for a modelocked vertical external-cavity surface-emitting laser is studied using an expanded form of the transverse Maxwell semiconductor Bloch equations. The influence of the incidence angle and relative cavity arm lengths is considered with respect to both the pump-probe computed instantaneous gain and group delay dispersion and the converged modelocked state. Changes in the angle are seen to lead to modest changes in dispersion but significant deformations of the modelocked pulse. Large changes in relative arm lengths are seen to lead to modest changes in the modelocked pulse with optimal pulses being observed with a 1:1 arm length ratio. The underlying microscopic dynamics are shown to drive these behaviors. This work provides a theoretical means to optimize experimental cavity geometry for desirable modelocking behaviors.

Metasurface-integrated vertical cavity surface-emitting lasers for programmable directional lasing emissions.

Vertical cavity surface-emitting lasers (VCSELs) have made indispensable contributions to the development of modern optoelectronic technologies. However, arbitrary beam shaping of VCSELs within a compact system has remained inaccessible until now. The emerging ultra-thin flat optical structures, namely metasurfaces, offer a powerful technique to manipulate electromagnetic fields with subwavelength spatial resolution. Here, we show that the monolithic integration of dielectric metasurfaces with VCSELs enables remarkable arbitrary control of the laser beam profiles, including self-collimation, Bessel and Vortex lasers, with high efficiency. Such wafer-level integration of metasurface through VCSEL-compatible technology simplifies the assembling process and preserves the high performance of the VCSELs. We envision that our approach can be implemented in various wide-field applications, such as optical fibre communications, laser printing, smartphones, optical sensing, face recognition, directional displays and ultra-compact light detection and ranging (LiDAR).

Thermal lensing effects on lateral leakage in GaN-based vertical-cavity surface-emitting laser cavities.

Lateral leakage of light has been identified as a detrimental loss source in many suggested and experimentally realized GaN-based VCSELs. In the present work we include thermal effects to realistically account for the substantial Joule heating in these devices. In contrast to what could be expected from the previous results, the induced thermal lensing does not make antiguided cavities more positively guided, so that they approach the unguided regime with extremely high lateral leakage. Rather, thermal lensing strongly suppresses lateral leakage for both antiguided and guided cavities. This is explained in terms of lowered launch of power from the central part of the cavity and/or lower total internal reflection in the peripheral part; the former effect is active in all cavities whereas the latter only contributes to the very strongly reduced leakage in weakly antiguided cavities. Thermal lensing suppresses lateral leakage both for the fundamental and the first higher order mode, but a strong modal discrimination is still achieved for the antiguided cavities. Thus, strongly antiguided cavities could be used to achieve single-mode devices, but at the cost of slightly higher threshold gain and stronger temperature dependent performance characteristics.

亚波长光栅对微机电系统波长可调谐垂直腔面发射激光器的影响

亚波长光栅对微机电系统波长可调谐垂直腔面发射激光器的影响

Engineering the Lateral Optical Guiding in Gallium Nitride-Based Vertical-Cavity Surface-Emitting Laser Cavities to Reach the Lowest Threshold Gain

In order to improve the current injection in GaN-based blue vertical-cavity surface-emitting lasers (VCSELs) a dielectric aperture is generally used in combination with an indium–tin-oxide (ITO) layer on the top intracavity p-contact layer. The most straightforward way to realize this introduces a depression of the structure near the optical axis and we show, by using a two-dimensional (2D) effective index method and a three-dimensional (3D) coupled-cavity beam propagation method, that this typically results in optically anti-guided structures with associated high optical losses and thus very high threshold gains. Remarkably, the threshold gain reduces with increased negative guiding, which is due to improved lateral confinement and reduction of lateral leakage. Still, moderately positively guided designs should be preferred to avoid the detrimental effect of lateral leakage and high diffraction loss. To ensure positive index guiding, we propose to planarize the structure or introduce an elevation near the optical axis by additional processing, with an associated reduction in threshold material gain from 6000 to 2000 cm-1 for the studied structures.

Various Elements of Heat Sources within an Optimized Photonic Crystal Vertical Cavity Surface Emitting Laser: Influence of Hole Etching Depth

Various Elements of Heat Sources within an Optimized Photonic Crystal Vertical Cavity Surface Emitting Laser: Influence of Hole Etching Depth

Giant Wavelength–Temperature Dependence of a Micro Machined Vertical Cavity Surface Emitting Laser with a Thermally Actuated Cantilever Structure

Giant Wavelength–Temperature Dependence of a Micro Machined Vertical Cavity Surface Emitting Laser with a Thermally Actuated Cantilever Structure

Giant Wavelength–Temperature Dependence of a Micro Machined Vertical Cavity Surface Emitting Laser with a Thermally Actuated Cantilever Structure

We present the modeling and the experimental result of a micro machined vertical cavity surface emitting laser with a thermally actuated semiconductor/SiO2 cantilever structure. The modeling result shows a giant wavelength–temperature dependence of over 3.5 nm/K. The fabricated device exhibits a temperature dependence of 0.79 nm/K, which is 10 times larger than that of conventional vertical cavity surface emitting lasers (VCSELs).

Noise Correlation, Regenerative Amplification, and the Linewidth Enhancement Factor of a Vertical-Cavity Surface-Emitting Laser

This letter reports on amplitude and frequency noise correlation measurements as well as on optical injection experiments related to the linewidth enhancement factor a of a vertical- cavity surface-emitting laser (VCSEL). It is shown that the correlation in VCSELs is not dominated by alpha; consequently, such experiments yield very little information on its value. Measuring the regenerative amplification of a weak injected optical probe turned out to be a robust approach that can not only give accurately the relaxation oscillation frequency and the damping rate but a good estimate of alpha as well. Finally, these experiments are combined with previously published data to increase the number of techniques applied to the measurement of alpha of a single semiconductor laser up to 11.

GaInNAs(Sb) surface normal devices

AbstractAfter a decade of intensive research on GaInNAs(Sb) on GaAs alloys, this paper summarizes some of the key properties of these III–V alloys and presents current progress in their exploitation in a variety of surface‐normal operating devices such as Vertical (External)‐Cavity Surface‐Emitting Lasers (V(E)CSELs) and SEmiconductor Saturable Absorber Mirrors (SESAMs). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

920-nm Vertical-External-Cavity Surface-Emitting Lasers With a Slope Efficiency of 58% at Room Temperature

We report a high-power fundamental transverse mode operation of an optically pumped 920-nm vertical-external- cavity surface-emitting laser. The effects of the gain related structural parameters on the laser performance are investigated. Based on the optimization of the gain structure and the thermal management, a maximum pump-limited output power of 12 W in a TEM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">00</sub> mode with a slope efficiency of 58% (input power of 24 W) was achieved at room temperature.

Determining the temporally and radially resolved temperature distribution inside a pulsed broad-area vertical-cavity surface-emitting laser cavity

The authors experimentally determine temporally and radially resolved profiles of the temperature distribution within the cavity of a broad-area vertical-cavity surface-emitting laser in pulsed operation. For this, the recently discovered state of spatially incoherent emission [M. Peeters et al., Opt. Express 13, 9337 (2005)] is harnessed. Using single-shot measurements of spectrally resolved near field profiles acquired by a fast-gated charge coupled device camera, the wavelength shift due to heating of the device is temporally and radially resolved. From the wavelength shift the temperature shift is extracted, which finally allows for determination of absolute temperature profiles.

Interpretation of polarization pinning due to scattering loss differentiation in asymmetric vertical-cavity surface-emitting laser cavities

The asymmetric aperture geometry in vertical-cavity surface-emitting laser cavities has long been known through experiments to effectively pin the polarization state of the output laser emission. In this article, we present a theoretical explanation for the observed effects due to noncircular aperture shape. The crux of our theory is that the unequal scattering losses of the laser beam between orthogonal polarizations of the same cavity eigenmodes lead to polarization pinning. Polarization-dependent calculations for elliptic apertures show that the scattering losses are lower when the polarization mode is aligned with the longest aperture axis, in agreement with experimental observations. This imbalance in scattering losses is higher than any intrinsic gain-related polarization dependence, and we suggest that it is the determining factor for polarization selection above a few-percent asymmetry in cavity geometry.

Operation of a Passively Mode-Locked Extended-Cavity Surface-Emitting Diode Laser in Multi-GHz Regime

We report on passive mode-locking of vertical cavity surface-emitting diode lasers at 980-nm wavelength, applied to different extended resonator configurations. Stable mode-locking producing pulses of approximately 50 ps in duration at up to 6-GHz repetition rate has been achieved. The use of external feedback results in pronounced harmonic pulse generation, extending the operational range of these new devices.

Fabrication of Substrate-Independent Hybrid Distributed Bragg Reflectors Using Metallic Wafer Bonding

A novel hybrid distributed Bragg reflector (DBR) consisting of a substrate-independent amorphous Si-Al-oxide stack and a Cr-Au-Ni-AuGe metallic bonding layer is developed for optoelectronic applications. The metal layers serve as a high-reflectance mirror as well as an adhesion material used in wafer bonding. The hybrid DBR utilizing the reflective metals can achieve a reflectivity of above 99.95% in merely six periods. In addition, the hybrid DBR can adjoin heterogeneous materials at a low temperature of 320/spl deg/C using a simple metallic bonding process. The hybrid DBR has been successfully applied to the fabrication of 1.55-μm GaInAsP-InP vertical-cavity surface-emitting laser cavities on Si substrates.

2-D VCSEL model for investigation of dynamic fiber coupling and spatially filtered noise

We propose a set of transformed two-dimensional (2-D) rate equations, which allow the computation of dynamic gain competition resulting from inhomogeneous field and carrier spatial distributions inside a vertical cavity surface-emitting laser cavity. Any explicit spatial dependency has been removed from the modified equations, reducing the computational time by several orders of magnitude. Resulting 2-D dynamic intensity profiles allow investigating effects related to improper fiber coupling due to transverse misalignment between laser beam and fiber. Although the expected increased relative intensity noise (RIN) levels associated with mode partition noise are observed, other effects might have larger contributions to the total noise under specific conditions. We show that the minimum RIN level is not necessarily reached for zero misalignment, but at positions where modes with broad far-field profiles and low power experience important filtering.

Different regimes of low-frequency fluctuations in vertical-cavity surface-emitting lasers

A numerical study of vertical-cavity surface-emitting lasers with optical feedback demonstrates the existence of two different types of low-frequency fluctuations (LFFs). The competition of two equally dominant polarization modes characterizes one type of LFF, while the other type is characterized by power drops in a dominant polarization mode and power bursts in the orthogonal depressed mode. We characterize and compare these two types of LFFs on the basis of their polarization properties and their dependency on the laser parameters. We show furthermore that a transition is possible from one type of LFF to the other, depending on the values of the linear anisotropies of the vertical-cavity surface-emitting laser cavity.

Study of a micro-machined tunable all air gap vertical cavity surface emitting laser

Wavelength tunable vertical cavity surface-emitting lasers (VCSELs) are potentially useful for future optical communications. The performance of a 1.3 μm tunable all air gap VCSEL is presented. The VCSEL consists of three air gap/InP Distributed Bragg Reflectors (DBR) below the active region, three air gap and four InP layers above the active region. The lowest InP layer acts as a tunable membrane. The actuation process results in an upbending of this membrane. Continuous wavelength tuning over 70 nm around 1.3 μm for a 13-V bias actuation has been demonstrated.

Design of a 364 nm Electrically Pumped Multi-Quantum Well Continuous Wave Nitride Vertical Cavity Surface Emitting Laser

ABSTRACTShort-wavelength vertical cavity surface emitting lasers (VCSELS) are typically important for high-density optical memory and optical imaging systems. An AlGaN/GaN multiquantum well (MQW) VCSEL was designed for operation at wavelength of 364 nm. The design process consisted of careful selection of materials and optimization of the parameters for distributed Bragg reflector (DBR) stacks, active region, and calculation of the threshold current density, external quantum efficiency, and threshold carrier concentration. InGaN/AlGaN material system was selected for constructing DBR stacks in order to minimize power dissipation and to achieve high reflectivity. A reflectivity of 99% was calculated for 33 pairs in the bottom DBR stack and 97% was calculated for 30 pairs in the top DBR stack. An external quantum efficiency of 85% has been achieved through parametric optimization. Results were comparable to that of the similar structures based on the review of recent literatures.