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1.
Continuous-wave (CW) performance of modern oxide-confined (OC) vertical-cavity surface-emitting diode lasers (VCSELs) at room
and elevated temperatures is investigated with the aid of the comprehensive fully self-consistent optical-electrical-thermal-gain
model. A standard OC GaInNAs/GaAs double-quantum-well VCSEL emitting the 1.3-μm radiation is used as a typical modern VCSEL
structure. The oxide aperture is placed at the anti-node position of an optical standing wave within a VCSEL cavity. The desired
single-fundamental-mode (SFM) operation has been found to be expected only in VCSELs equipped with relatively small active
regions of diameters equal or smaller than 10 μm. Therefore a proton implantation used as an radial additional confinement
of the current spreading from the upper annular contact towards the centrally located active region is proposed and its impact
on the VCSEL performance is investigated. The above structure modification has been found to enable a radical improvement
in the VCSEL performance. In particular, in this case, the SFM VCSEL operation is possible even in VCSELs with quite large
active regions and for much wider ambient-temperature range than in the standard OC VCSELs. 相似文献
2.
?ukasz Piskorski Robert P. Sarza?a W?odzimierz Nakwaski 《Applied Physics A: Materials Science & Processing》2010,98(3):651-657
Minimal optical attenuation of plastic (polymer) optical fibres (POFs) corresponds to the 650-nm wavelength. Currently the
GaInP/AlGaInP quantum-well (QW) oxide-confined (OC) vertical-cavity surface-emitting diode lasers (VCSELs) are undoubtedly
the laser devices most suited to be used in 650-nm POF optical communication, for which the stable single-fundamental-mode
LP01 emission (SFM) is definitely the one most desired. In the present paper, the comprehensive fully self-consistent VCSEL model
is used to examine mode selectivity of the above VCSELs. An increase in the VCSEL active-region diameter leads to a gradual
modification of the current injection into this region and subsequent carrier radial diffusion within it before their recombination,
which is followed by an essential transformation of active-region optical-gain profiles deciding upon an excitation of successive
transverse modes. In standard arsenide OC VCSELs, SFM operation is usually limited to relatively small active regions. But
for a room-temperature continuous-wave operation of the GaInP/AlGaInP VCSELs, the fundamental LP01 mode remains surprisingly the lowest-threshold one up to relatively large active regions of 9-μm diameters. Nevertheless,
in such VCSELs, thresholds of many LP modes become very similar to one another, which leads to their relatively poor mode
selectivity and an unwanted multi-mode operation for higher output powers. 相似文献
3.
Structure optimisation of the GaAs-based GaInNAsSb/GaNAs quantum-well (QW) vertical-cavity surface-emitting diode lasers (VCSELs)
has been carried out using the comprehensive three-dimensional self-consistent physical model of their room-temperature (RT)
continuous-wave (CW) threshold operation. The model has been applied to investigate a possibility to use these devices as
carrier-wave lasing sources in the third-generation optical-fibre communication. In this simulation, all physical (optical,
electrical, thermal and gain) phenomena crucial for a laser operation including all important interactions between them are
taken into consideration. As expected, the 1.5λ-cavity VCSEL has been found to demonstrate the lowest RT CW threshold. However,
for many VCSEL applications, the analogous VCSEL equipped with a longer 3λ-cavity should be recommended because it exhibits
only slightly higher threshold but manifest much better mode selectivity – the desired single-fundamental-mode operation has
been preserved in these devices up to at least 380 K. The Auger recombination has been found to be decidedly the main reason
of the threshold current increase at higher temperatures. A proper initial red detuning of the resonator wavelength with respect
to the gain spectrum may drastically decrease CW lasing thresholds, especially at higher temperatures. 相似文献
4.
Room-temperature (RT) continuous-wave (CW) performance of modern 1300-nm oxide-confined In(Ga)As/GaAs quantum-dot (QD) vertical-cavity
surface-emitting diode lasers (VCSELs) taking advantage of many QD sheets is investigated using our comprehensive self-consistent
simulation model to suggest their optimal design. Obviously, quantum dots should be as uniform as possible and as dense as
possible to ensure high enough optical gain. Besides, our simulation reveals that efficient and uniform current injection
into VCSEL active regions necessary to enhance excitation of the desired fundamental LP01 mode is accomplished in the VCSEL configuration with the broad-area bottom contact and the ring upper one as well as with
the oxide aperture localized within the first period of the upper p-type DBR. The doping of the DBR mirrors is chosen as a
compromise between their high enough electrical conductivity and low enough free-carrier absorption. The oxide aperture is
additionally introducing the radial optical waveguiding. Moreover, our analysis has been concluded that VCSEL active regions
should be composed of at least 9 QD sheets to acquire efficient RT CW operation. Furthermore, rather longer optical cavities
are recommended in this case because localization of QD sheets should be adjusted to the anti-node positions of the optical
cavity standing wave. 相似文献
5.
An experimental study has been presented of the oxide-confined vertical-cavity surface-emitting lasers (VCSEL) operating in
the 850 nm region of the electromagnetic spectrum. In this regard, various relevant VCSEL samples with numerous oxide aperture
sizes have been fabricated and characterized. Thorough investigations of the electrical as well as optical characteristics
of the fabricated samples have been performed which includes the overall device performance as a function of the oxidize aperture
sizes. It is reported that the VCSEL with oxide aperture size <10 μm require low threshold currents (<1 mA). Further, the
differential quantum efficiencies up to 28% were measured for a number of these devices. It is found that devices employing
oxide aperture of 10 to 15 μm shows promising electro-optical characteristics for 850 nm oxide VCSEL optimization. 相似文献
6.
M. S. Alias S. Shaari P. O. Leisher K. D. Choquette 《Applied physics. B, Lasers and optics》2010,100(3):453-459
In this letter, we report on single-mode operation of originally multi-mode oxide VCSEL by using etched photonic crystal air
holes and unique trench structure. The device fabrication utilized conventional photolithography; with simplified lithography
step of self-aligning the photonic crystal and trench structures to the laser aperture for efficient and vigorous device processing.
The fabricated photonic crystal VCSEL with trench device exhibits a single-mode output power of 0.7 mW, threshold current
of 3.5 mA, slope efficiency of 0.10 W/A, and continuous single-mode output spectra at wide operating current range. The results
are compared with conventional multi-mode oxide VCSEL of similar device geometry. In addition, theoretical analysis is presented
for developing further understanding of the photonic crystal VCSEL. 相似文献
7.
Y. Ding W. J. Fan D. W. Xu C. Z. Tong Y. Liu L. J. Zhao 《Applied physics. B, Lasers and optics》2010,98(4):773-778
We present the fabrication process and experimental results of 850-nm oxide-confined vertical cavity surface emitting lasers
(VCSELs) fabricated by using dielectric-free approach. The threshold current of 0.4 mA, which corresponds to the threshold
current density of 0.5 kA/cm2, differential resistance of 76 Ω, and maximum output power of more than 5 mW are achieved for the dielectric-free VCSEL with
a square oxide aperture size of 9 μm at room temperature (RT). L–I–V characteristics of the dielectric-free VCSEL are compared with those of conventional VCSEL with the similar aperture size,
which indicates the way to realize low-cost, low-power consumption VCSELs with extremely simple process. Preliminary study
of the temperature-dependent L–I characteristics and modulation response of the dielectric-free VCSEL are also presented. 相似文献
8.
We establish a novel method of controlling the transverse modes of vertical cavity surface emitting lasers(VCSELs)to achieve 1 mW single-fundamental-mode lasing. A dielectric mode filter is installed on top of the VCSEL. The dielectric layer(SiO_2) is deposited and patterned to modify the mirror reflectivity across the oxide aperture via antiphase reflections.This mode selection is nondestructive and universally applicable for other structures under single transverse mode. Destructive etching techniques(dry/wet) or epitaxial regrowth are also not required. This method simplifies the preparation process and improves the repeatability of the device. Measurements show that under continuous-wave current injection, the side-mode suppression ratio exceeds 30 dB. 相似文献
9.
This paper reports a numerical analysis of nitride VCSELs with indium-tin-oxide current spreading layers and AlN apertures. The results show that the thickness, location and diameter of the AlN aperture significantly influence the optical and electrical properties of the VCSEL. 相似文献
10.
The influence of the oxide aperture radius on the characteristics of a long-wavelength vertical-cavity surface-emitting laser (VCSEL) lasing at 1550 nm is presented in this paper. While previous works in the literature mostly investigate the scaling effects of short-wavelength VCSELs. The importance of studying the effects of long-wavelength operation should not be underestimated, as it could be used in fiber optics communication to mitigate dispersion and attenuation of the channel. Using the oxide-confined VCSEL model, the dynamic operations were examined taking into account the carrier-noise, photon-noise and phase-noise, including feedback of the external cavity. Our simulations show that by reducing the oxide aperture up to a given optimal radius, an improvement in the device's characteristics can be demonstrated. Below this value, performance degradation is expected due to increased diffraction losses, reduced confinement factor and enhanced spontaneous emission. 相似文献
11.
Robert P. Sarzała Łukasz Piskorski 《Applied Physics A: Materials Science & Processing》2011,102(2):359-366
The comprehensive optical-electrical-thermal-recombination self-consistent VCSEL model is used to compare the performance
of oxide-confined (OC) and proton-implanted (PI) VCSELs and to optimise their structures. Generally index-guided (IG) OC VCSELs
demonstrate lower lasing thresholds whereas both gain-guided (GG) OC and PI ones manifest much better mode selectivity. Therefore,
their either low-threshold IG or mode-selective GG versions may be intentionally used for different VCSEL applications. Lasing
thresholds of OC IG VCSELs have been found to be very sensitive to the exact localisation of their thin oxide apertures, which
should be shifted as close as possible towards the anti-node position. PI VCSELs, on the other hand, are simpler and cheaper
in their manufacturing than OC ones. Although lower threshold currents are manifested by PI VCSELs with very thick implanted
regions, lower threshold powers are achieved in these devices with much thicker upper unaffected layer used for the radial
current flow from the ring contact towards the laser axis. Paradoxically poor thermal properties of PI VCSELs enable lower
lasing thresholds of slightly detuned devices. To conclude, cheaper and mode-selective PI VCSELs may be used instead of OC
ones in many of their applications provided ambient temperatures and laser outputs are not too high. 相似文献
12.
基于氧化限制型内腔接触垂直腔面发射激光器(VCSEL) 结构设计, 研究了VCSEL的多横模分布及其模式波长分裂特性与氧化孔径尺寸、形状的关系. 在实验基础上, 通过建立有效折射率模型, 并利用标量亥姆霍兹方程的迭代算法理论, 分别对椭圆形氧化孔径和圆形氧化孔径VCSEL的横向模式特性进行模拟研究, 计算得到不同形状孔径的多横模光场分布情况, 同时测量得到高阶横模多频输出光谱. 研究发现, 椭圆氧化孔形状不仅影响横模分布特性, 还会导致每个模式的波长产生分裂, 分裂值可达0.037 nm. 同时, 随着氧化孔径的增大, 波长分裂影响会逐渐减小, 直至趋近于圆形氧化孔径的分布特性. 研究结果为进一步实现氧化限制型VCSEL的多横模锁定提供了有益参考和借鉴. 相似文献
13.
W. Nakwaski 《Applied Physics A: Materials Science & Processing》1995,61(2):123-127
In this paper, the current flow through the whole volume of the proton-implanted Vertical-Cavity top-Surface-Emitting Lasers (VCSELs) is analysed in detail. A simple approximate analytical relation was derived for a radial distribution of the current density entering active regions of those lasers. This distribution is nearly uniform in the case of VCSELs with a very small active region, but is becoming more and more non-uniform with an increase in its size. In VCSELs with very large active regions, current is flowing practically only within a narrow annular area close to the active-region perimeter. The VCSEL series electrical resistance is determined as a function of its active-region radius. 相似文献
14.
High-speed, oxide-confined, polyimide-planarized 850 nm vertical-cavity surface-emitting lasers (VCSELs) with oxide aperture diameters of 9, 10, 12, 15, 20, and 30 μm have been fabricated and characterized. For a 9 μm oxide aperture diameter, the lasers exhibit a resonance frequency, a 3-dB modulation frequency, and a modulation current efficiency factor (MCEF) up to 12.4, 16.5 GHz, and 10.9 GHz/mA1/2, respectively, at only 7.9 kA/cm2. Threshold voltage and current were 1.45 V and 0.7 mA, respectively. It is demonstrated that increasing the resonance frequency with bias does not guarantee a higher modulation bandwidth. The influence of oxide aperture scaling effect on VCSEL performance is presented. 相似文献
15.
Proposed on-axis current channeling through the use of photoactive layer(s) in vertical-cavity surface emitting laser (VCSEL) cavities counteracts hole burning and allows single mode operation at high currents. The photoactive layers act as variable resistivity screens whose radial 'aperture' is controlled by the light itself, providing an efficient feedback for mode control. Absorption of a small fraction of the light intensity suffices for significant on-axis current peaking with minimum efficiency loss and optical mode distortion. Fabrication is implemented during the molecular beam epitaxy phase without wafer post-processing, as for oxide apertures. 相似文献
16.
B.N. Upadhyaya S.C. Vishwakarma A. Choubey R.K. Jain Sabir Ali D.K. Agrawal A.K. Nath 《Optics & Laser Technology》2008,40(2):337-342
Here, we report on the development of an efficient, high peak power lamp pumped Nd:YAG laser with time-shared fiber optic beam delivery. A maximum average output power of 270 W with 100 J maximum pulse energy and 5 kW peak power has been achieved with an electrical to laser conversion efficiency of 5.4%, which is on higher side for typical lamp pumped solid-state lasers. We have improved efficiency by spectral conversion and water flow optimization in the pump cavity, with a resulting beam quality comparable to commercial systems of similar power level. The resonator has been designed for stable operation from single-shot to 200 Hz repetition rate. A study of pulse-to-pulse laser energy stability for different resonator configurations has also been performed. The resonator was designed to achieve a good beam quality for the whole range of operation with a maximum beam parameter product of 15 mm mrad (M245). A simple mechanism for time-shared fiber optic port selection has also been devised. Material processing applications such as cutting of stainless steel sheets up to 14 mm thickness and welding of metals such as carbon steel with weld depths up to 2 mm using the developed laser system has also been reported. 相似文献
17.
An experimental study has been presented of the oxide-confined vertical-cavity surface-emitting lasers (VCSELs) operating in the 850 nm region of the electromagnetic spectrum. In this regard, various relevant VCSEL samples with numerous oxide aperture sizes have been fabricated and characterized. Thorough investigations of the electrical as well as optical characteristics of the fabricated samples have been performed, which include the overall device performance as a function of the oxidize aperture sizes. It is reported that the VCSELs with oxide aperture size <10 μm require low threshold currents (<1 mA). Further, the differential quantum efficiencies up to 28% corresponding to wall-plug efficiencies of up to 15% were measured for a number of these devices. 相似文献
18.
Mohd Sharizal Alias Sahbudin Shaari Paul O. Leisher Kent D. Choquette 《Photonics and Nanostructures》2010,8(1):38-46
Single transverse mode control is achieved for multimode GaAs-based VCSEL by utilizing photonic crystal design and etched trench structure. Theoretical analysis is initially performed for photonic crystal design with various lattice constants and air holes diameter. The fabricated photonic crystal VCSEL with etched trench structure exhibits single mode output power of 0.7 mW, threshold current of 3.5 mA, slope efficiency of 0.10 W/A, and continuous single mode output spectrum throughout a wide operating current range. Comparison of typical oxide VCSEL, trench oxide VCSEL, and photonic crystal oxide VCSEL employing trench structure is presented. By combining photonic crystal and trench structure, single transverse mode operation of photonic crystal VCSEL can be much more strictly controlled. 相似文献
19.
20.
T. Czyszanowski 《Opto-Electronics Review》2010,18(1):56-62
Results of the self-consistent comprehensive analysis of a room-temperature operation of InP-based 1300-nm AlInGaAs photonic-crystal
(PhC) VCSELs are presented. In particular, an influence of PhC parameters on thermal effects within VCSEL volume and its emission
wavelength are analysed. The PhC has been found to introduce a number of opposite effects including a possible light leakage
through PhC holes. From one side, PhC holes make more difficult heat-flux extraction from VCSEL volume leading to higher temperature
increases within it. But, from the other side, a properly manufactured PhC creates an efficient radial confinement mechanism
for VCSEL radiation field. It enhances an interaction between the field and the active-region carriers leading to a decrease
in both the VCSEL lasing threshold and temperature increases. Seemingly both effects may similarly affect VCSEL operation,
but our analysis revealed, that thermal properties of the PhC VCSEL are mainly dependent on an efficient confinement of its
radiation field within the active region impeding a mode leakage through PhC holes, whereas an importance of deterioration
of heat-flux extraction from VCSEL volume is much less essential. The wavelength shift induced by a change of PhC parameters
has been found not to exceed 4×10−3 μm. 相似文献