Search query: Polarization properties of vertical-cavity surface-emitting lasers

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abstract: Polarization state selection, polarization state dynamics, and polarization switching of a quantum well vertical cavity surface emitting laser (VCSEL) for the lowest order transverse spatial mode of the laser is explored using a recently developed model that incorporates material birefringence, the saturable dispersion characteristic of semiconductor physics, and the sensitivity of the transitions in the material to the vector character of the electric field amplitude. Three features contribute to the observed linearly polarized states of emission: linear birefringence, linear gain or loss anisotropies, and an intermediate relaxation rate for imbalances in the populations of the magnetic sublevels. In the absence of either birefringence or saturable dispersion, the gain or loss anisotropies dictate stability for the linearly polarized mode with higher net gain; hence, switching is only possible if the relative strength of the net gain for the two modes is reversed. When birefringence and saturable dispersion are both present, there are possibilities of bistability, monostability, and dynamical instability, including switching by destabilization of the mode with the higher gain to loss ratio in favor of the weaker mode. We compare our analytical and numerical results with recent experimental results on bistability and switchings caused by changes in the injection current and changes in the intensity of an injected optical signal.
author_names: Josep Martin-Regalado

Franco Prati

Maxi San Miguel

Neal Broadus Abraham
title: Polarization properties of vertical cavity surface emitting lasers
year: 1997

abstract: Influences of variable angle polarization rotated optical feedback on polarization properties of vertical cavity surface emitting lasers (VCSELs) are investigated numerically. For the so called case A (x polarization) feedback, only the x mode is selected to pass through the feedback loop. As the polarization angle is varied from 0 degrees to 90 degrees, the dominant polarization mode switching can be observed even for fixed feedback strength and bias current. For the so called case B (xy polarization) feedback, the total outputs of the VCSEL pass through the feedback loop. The polarization property is much different from case A. The dominant polarization mode switching occurs not in the entire range of polarization angles, however, but in the so called critical angle, from where the intensities of both polarization modes become comparable to each other and keep around constant values, and can be observed. In addition, the complementary properties of intensities between the two polarization modes for both cases are evaluated quantitatively in terms of the defined normalized intensity.
author_names: Shuiying Xiang

Wei Pan

Lianshan Yan

Bin Luo

Ning Jiang

Lei Yang
title: Polarization properties of vertical cavity surface emitting lasers subject to feedback with variably rotated polarization angle.
venue: Applied optics
year: 2009

abstract: The polarization properties of the light emitted by vertical cavity surface emitting semiconductor lasers are studied by means of a four level scheme which includes misaligned linear phase and amplitude anisotropies. First we investigate the system stability characteristics, demonstrating that upon increasing the pumping level a polarization switching may take place both from the lower to the higher and from the higher to the lower frequency states. Then we study the laser stationary states identifying the role played by nonlinear effects and demonstrating that noticeable deviations from linear behavior are induced by the simultaneous presence of misaligned phase and amplitude anisotropies with comparable magnitude.
author_names: Martino Travagnin
title: Linear anisotropies and polarization properties of vertical cavity surface emitting semiconductor lasers
year: 1997

abstract: In this paper, the influence of variable polarization angle (thp) of optical feedback (OF) on the polarization properties of a vertical cavity surface emitting lasers (VCSELs) is investigated experimentally. Parallel polarization optical feedback (PPOF) and orthogonal polarization optical feedback (OPOF) are employed, where the polarization light is re injected back into the laser. For the PPOF (OPOF) polarization of the feedback light is parallel (orthogonal) to the polarization light of solitary VCSEL. With respect to PPOF, no polarization switching (PS) occurs over the entire range of thp. However, when apply both the PPOF and OPOF PS takes places for a fixed OF level and at certain value of thp with increasing bias current (Ib) Furthermore, when increasing thp PS occur for a fixed OF level and bias Ib. The results show that a variable polarization optical feedback technique is an effective tool for controlling the polarization instabilities of VCSEL.
author_names: Salam Nazhan

Zabih Ghassemlooy

Krishna Busawon
title: POLARIZATION PROPERTIES OF VERTICAL CAVITY SURFACE EMITTING LASERS SUBJECT TO VARIABLE OPTICAL FEEDBACK POLARIZATION ANGLE
year: 2015

abstract: M5 S/ P of the powers in the two polarization modes of the laser is one of the essential parameters governing the VCSELs quantum noise behavior. The generation of amplitude squeezed states of light is only possible for two well selected cases which are the ideal two polarization mode laser (M'1) and the ideal singlepolarization mode laser (M'0) respectively. Furthermore, we show that gain suppression, as well as other relevant semiconductor parameters, have also to be taken into account to model realistically the VCSEL's quantum noise. These theoretical investigations are very well supported by our experimental results. We demonstrate experimentally that indeed there exists a direct link between the parameter M and the shot noise normalized amplitude noise. In a two polarization mode laser as, e.g. represented by a large diameter air post VCSEL, squeezed states could not be generated because of insufficiently low values of M even though a strong anticorrelation between the two modes exists. With a single polarization mode laser, as realized with small diameter oxide confined VCSELs, we have been able to demonstrate the generation of single mode squeezed light with a VCSEL. A squeezing level of 0.9 dB has been measured, which with the detection efficiency corrected, results in 1.3 dB at the VCSEL upper facet. @S1050 2947~99!08010 5#
author_names: Jean-Luc Vey

Ch Degen

Karsten Auen

Wolfgang Elsasser
title: Quantum noise and polarization properties of vertical cavity surface emitting lasers
year: 1999

author_names: S F Yu
title: Polarization Properties of Vertical Cavity Surface Emitting Lasers
year: 2005

abstract: We have studied the polarization properties of vertical cavity surface emitting lasers with various patterns in tilted pillar structures. Laser pillars with circular, square, diamond and rectangular patterns were formed by reactive ion beam etching. Tilted pillars were obtained by tilting the [110] or [110] direction of the (001) GaAs substrate. The sizes of pillars varied from 10 um to 20 um and their tilt angle varied from 15deg to 30deg toward [110] or [110] with respect to [001] The vertical asymmetry of the tilted pillar strongly affected the polarization selectivity of vertical cavity surface emitting lasers with the tilted pillar, rather than the anisotropy of an overlapped region in the planar direction.
author_names: Min Park

Byung Tae Ahn

Hye Yong Chu

Byueng-Su Yoo

Hyo-Hoon Park
title: Polarization Properties of Vertical Cavity Surface Emitting Lasers with Various Patterns in Tilted Pillar Structures
year: 1998

abstract: Vertical cavity surface emitting lasers (VCSELs) have multiple beneficial properties in quantum key distribution (QKD) However, polarization switching (PS) which happens between two orthogonally polarized eigenmodes, is characteristic of these lasers. PS is extremely problematic if it is unwanted in all polarization sensitive applications. The origin and properties of PS is discussed, along with potential error scenarios introduced to QKD protocols BB84 and B92. We propose a new transmitter design for the BB84 protocol using only two VCSELs both corresponding to one of the two bases in which polarized photons are sent which are modulated in polarization, purposely generating switches between two orthogonally polarized modes. The methods of polarization modulation are described, along with advantages and design difficulties of the new design. We also consider the possibility of a spectral attack performed by an eavesdropper, originating from the frequency splitting between the polarization eigenmodes of a single VCSEL, and offer a theoretical solution that can protect the key from eavesdroppers utilizing this kind of attack.
author_names: Agoston Schranz

Eszter Udvary
title: Polarization Modulated Vertical Cavity Surface Emitting Lasers in Quantum Key Distribution
year: 2019

abstract: Abstract This paper presents the design and numerical simulation of vertical cavity surface emitting laser (VCSEL) incorporating a high contrast grating (HCG) by using a three dimensional (3 D) finite difference time domain (FDTD) method. The polarization dependence of HCG parameters as well as HCG reflector properties are numerically studied. We investigate the resonant spectra behavior and modal properties with respect to different aperture size. Furthermore, the quality factor (Q factor) related to modal loss is calculated, and is used to explain the mode selection of the HCG VCSELs. Based on the simulation and analysis, it is found that the designed HCG VCSELs exhibit larger mode discrimination compared to the conventional VCSELs. Our work could provide guidelines for designing and optimizing polarization stable, single mode VCSELs for use in chip scale Cs atomic clocks.
author_names: Pingping Qiu

Wei Pang

Pan Fu

Mei-fan Li

Chonglei Sun

Jia Zhao

Yiyang Xie

Qiang Kan
title: Numerical investigation of vertical cavity surface emitting lasers incorporating a high contrast grating using 3 D FDTD method
year: 2020

abstract: Author(s) Kearns, Jared Advisor(s) Nakamura, Shuji Abstract: III N vertical cavity surface emitting lasers (VCSELs) show promise for numerous communications, lighting, display, and sensor applications due to their low threshold current, high beam quality, and arraying capabilities. Primarily, research has been focused on using c plane based devices, but non basal growth planes provide an interesting alternative due to a reduced quantum confined Stark effect; higher material gain; lower transparency current density; and inherent polarized emission. The anisotropic gain leads to VCSELs and VCSEL arrays where each laser is polarization locked along the a direction. At UCSB, an m plane VCSEL was first demonstrated in 2012 under pulsed injection and in 2018 under CW operation. Through that time, the device performance has improved and the polarization properties of the VCSELs has been experimentally verified. However, the wavelength of m plane lasers is severely limited due to poor indium incorporation and high defect formation, inhibiting their adoption in many applications. This led to the question of how the benefits of using m plane can be retained, such as the inherent polarization, while expanding the available wavelengths. The answer that was developed in this thesis is the use of a semipolar growth plane with higher indium uptake. After developing an epitaxial growth recipe and optimizing processing parameters for semipolar planes, we achieved the first demonstration of semipolar (20(21) VCSELs which were experimentally shown to be polarization locked along the a direction and emit in the blue region. The devices had a 5l cavity length, an ion implanted aperture, and a dual dielectric DBR design and showed an improvement in the differential efficiency, threshold current density and total output power relative to m plane VCSELs with the same design. However, there were issues. The devices were only able to lase under pulsed operation, up to a 70% duty cycle. Focused ion beam images in conjunction with COMSOL modeling was used to identify the key structural features that contributed to the high measured thermal impedance. Nearfield images suggest that the LP01 mode was lasing near the edge of the aperture. This commonly observed spatial misalignment introduced additional sources of loss beyond the expected material absorption loss, including mode overlap with the implanted region and the metal contacts. The effect of these absorbing layers on the device performance relative to simulation models was estimated and highlighted the need for proper mode control.To improve the optical confinement, devices using a buried tunnel junction (BTJ) scheme to confine the current were fabricated and were found to lack the excess losses due to absorption seen on the initial semipolar samples. Significant filamentation was observed on these samples and several characterization methods, including optical and thermal nearfield images, were used to identify the source of the filamentation. Further comparison of multiple BTJ samples with different index guiding showed that the mode behavior was driven by the interplay of inhomogeneous current injection and index guiding. The cause of the inhomogeneous current injection is projected to be due to doping variations in the p GaN but still requires further investigation for verification.
author_names: Jared A Kearns
title: Development of Semipolar III Nitride Vertical Cavity Surface Emitting Lasers
year: 2020