Vertical-cavity Semiconductor Lasers Research Articles

Dual-wavelength channel GHz repetition rate mode-locked VECSEL cavities sourced from a common gain medium.

Mode-locked vertical external cavity semiconductor lasers are a unique class of nonlinear dynamical systems driven far from equilibrium. We present a novel, to the best of our knowledge, experimental result, supported by rigorous microscopic simulations, of two coexisting mode-locked V-cavity configurations sourced by a common gain medium and operating as independent channels at angle controlled separated wavelengths. Microscopic simulations support pulses coincident on the common gain chip extracting photons from a nearby pair of coexisting kinetic holes burned in the carrier distributions.

Transition from traveling to motionless pulses in semiconductor lasers with saturable absorber

Semiconductor lasers show interesting pulse dynamics. We investigate, analytically and numerically, the transition from traveling to motionless pulses in vertical-cavity semiconductor lasers with a saturable absorber. Based on two different approaches, (i) the adiabatic elimination of the charge carriers corresponding to a class A laser and (ii) considering the laser dynamics close to lasing instability (class B lasers), we figure out the relationship between these pulses. The pulses exhibit a continuous transition between traveling to motionless ones. Starting from the asymptotic behavior of the pulse, we are able to set a formula for the pulse speed. In the limit of a small electric field envelope, we elucidate that the observed transition corresponds to the spontaneous breaking instability of reflection symmetry. Employing a reduction method, we set equations for the position, asymmetrical amplitude, and frequency of the pulse. This reduced pulse model shows quite fair agreement with numerical simulations for the different approaches considered for semiconductor lasers with a saturable absorber.

An OE-VLSI for parallel optical interconnection

This paper presents a prototype OE-VLSI (Optoelectronic-VLSI) with 12-channel input and output ports for optical parallel link applications. The OE-VLSI comprises of a 12-channel parallel VCSEL (Vertical Cavity Semi-conductor Laser) array and a 12-channel parallel Photo Diode array, a CPU, a 12-channel VCSEL driver array and a 12-channel optical front-end amplifier. The 12×10Gbps VCSEL driver array and the optical front-end amplifier array are fabricated in 0.18μm CMOS technology. The chip was partitioned into 12 parallel channels to demonstrate chip-to-chip interconnection functions appropriate for applications of OE-VLSI technology. The OE-VLSI chip has been validated on an optical parallel transmission system with bit-error-rate BER less than 10−12 and an aggregate 120Gpbs bandwidth.

Polarization axis fluctuations in a single mode VCSEL laser at 780nm

We present a transmission method to determine the polarization axis fluctuations for VCSEL (Vertical Cavity Surface Emitting Laser). The research is focused mainly on commercial lasers operatingat 780 nm, designed forlaser spectroscopy. The angle fluctuation of the laser linear axis polarization iselaborated to be less than 150 mrad. Measurement errors of this method are studied and calculated. The measurement uncertainty is ?1,4 mrad andthis is equivalent to ? 5? of arc.Changes of the linear polarization axis depending on the laser current and temperaturearepresented. Full Text: PDF References T. Ohtoshi et al., "Dependence of optical gain on crystal orientation in surface?emitting lasers with strained quantum wells", Appl. Phys. Lett.63, 1886 (1994). CrossRef K. Tateno et al., "Growth of vertical-cavity surface-emitting laser structures on GaAs (311)B substrates by metalorganic chemical vapor deposition", Appl. Phys. Lett.70, 3395 (1997). CrossRef O. Tadanaga et al., "An 850-nm InAlGaAs strained quantum-well vertical-cavity surface-emitting laser grown on GaAs (311)B substrate with high-polarization stability", IEEE Photon. Tech. Lett.12, 942 (2000) CrossRef K. Choquette, R. Leibenguth, "Control of vertical-cavity laser polarization with anisotropic transverse cavity geometries", IEEE Photon. Tech. Lett. 6, 40 (1994) CrossRef B. Weigl et al., "High-performance oxide-confined GaAs VCSELs", IEEE J. Sel. Top.Quantum Electron. 3, 409 (1997) CrossRef P. Dowd et al., "Complete polarisation control of GaAs gain-guided top-surface emitting vertical cavity lasers", Electron. Lett. 33, 1315 (1997) CrossRef M. Grabherr et al., "Volume production of polarization controlled single-mode VCSELs", Proc. SPIE,6908, 690803 (2008) CrossRef R. Roy et al., "First-Passage-Time Distributions under the Influence of Quantum Fluctuations in a Laser", Phys. Rev. Lett.45, 1486 (1980) CrossRef J. Martin-Regalado et al., "Polarization switching in vertical-cavity surface emitting lasers observed at constant active region temperature", Appl. Phys. Lett. 70, 3350 (1997) CrossRef M. B. Willemsen et al., "Polarization Switching of a Vertical-Cavity Semiconductor Laser as a Kramers Hopping Problem", Phys. Rev. Lett. 82, 4815 (1999) CrossRef M. B. Willemsen et al., "Anatomy of a Polarization Switch of a Vertical-Cavity Semiconductor Laser", Phys. Rev. Lett. 84, 4337 (2000) CrossRef T. Mukaihara et al., "Excess intensity noise originated from polarization fluctuation in vertical-cavity surface-emitting lasers", IEEE Photon. Technol. Lett. 7, 1113 (1995) CrossRef

Polarization axis fluctuations in a single mode VCSEL laser at 780nm

We present a transmission method to determine the polarization axis fluctuations for VCSEL (Vertical Cavity Surface Emitting Laser). The research is focused mainly on commercial lasers operatingat 780 nm, designed forlaser spectroscopy. The angle fluctuation of the laser linear axis polarization iselaborated to be less than 150 mrad. Measurement errors of this method are studied and calculated. The measurement uncertainty is ?1,4 mrad andthis is equivalent to ? 5? of arc.Changes of the linear polarization axis depending on the laser current and temperaturearepresented. Full Text: PDF References T. Ohtoshi et al., "Dependence of optical gain on crystal orientation in surface?emitting lasers with strained quantum wells", Appl. Phys. Lett.63, 1886 (1994). CrossRef K. Tateno et al., "Growth of vertical-cavity surface-emitting laser structures on GaAs (311)B substrates by metalorganic chemical vapor deposition", Appl. Phys. Lett.70, 3395 (1997). CrossRef O. Tadanaga et al., "An 850-nm InAlGaAs strained quantum-well vertical-cavity surface-emitting laser grown on GaAs (311)B substrate with high-polarization stability", IEEE Photon. Tech. Lett.12, 942 (2000) CrossRef K. Choquette, R. Leibenguth, "Control of vertical-cavity laser polarization with anisotropic transverse cavity geometries", IEEE Photon. Tech. Lett. 6, 40 (1994) CrossRef B. Weigl et al., "High-performance oxide-confined GaAs VCSELs", IEEE J. Sel. Top.Quantum Electron. 3, 409 (1997) CrossRef P. Dowd et al., "Complete polarisation control of GaAs gain-guided top-surface emitting vertical cavity lasers", Electron. Lett. 33, 1315 (1997) CrossRef M. Grabherr et al., "Volume production of polarization controlled single-mode VCSELs", Proc. SPIE,6908, 690803 (2008) CrossRef R. Roy et al., "First-Passage-Time Distributions under the Influence of Quantum Fluctuations in a Laser", Phys. Rev. Lett.45, 1486 (1980) CrossRef J. Martín-Regalado et al., "Polarization switching in vertical-cavity surface emitting lasers observed at constant active region temperature", Appl. Phys. Lett. 70, 3350 (1997) CrossRef M. B. Willemsen et al., "Polarization Switching of a Vertical-Cavity Semiconductor Laser as a Kramers Hopping Problem", Phys. Rev. Lett. 82, 4815 (1999) CrossRef M. B. Willemsen et al., "Anatomy of a Polarization Switch of a Vertical-Cavity Semiconductor Laser", Phys. Rev. Lett. 84, 4337 (2000) CrossRef T. Mukaihara et al., "Excess intensity noise originated from polarization fluctuation in vertical-cavity surface-emitting lasers", IEEE Photon. Technol. Lett. 7, 1113 (1995) CrossRef

Spacer and well pumping of InGaN vertical cavity semiconductor lasers with varying number of quantum wells

We have investigated the dependence of the threshold pump power and slope efficiency of 415 nm (In)GaN vertical cavity surface emitting lasers on the wavelength of the pump source and the number of quantum wells. InGaN double quantum well resonant-periodic-gain structures with 6, 8, and 10 periods have been compared. By barrier and well pumping of the samples with a 375 nm dye laser, a nearly 10 times reduction of the laser threshold was observed compared to pumping with a 337 nm nitrogen laser source. The laser threshold was found to be independent of the number of quantum wells. The slope efficiency seems to be not affected by the pump wavelength and resonant-periodic-gain periods. The results are discussed with a rate equation model that takes into account the inhomogeneous pumping of the quantum wells and optical thickness variations in the resonant-periodic-gain structure.

Fast generation of random bits based on polarization noises in a semiconductor vertical-cavity laser

It is experimentally demonstrated that intensity fluctuations on a selected polarization in a semi-conductor vertical-cavity laser are an effective source of entropy for fast generation of random bits. The effective generation rate is shown to be from 100 Mbps to 4.5 Gbps at the discretization frequency of 100 MHz, depending on how the random bits are extracted from the polarization noise. The generated sequences of random bits are characterized by low bias and absence of correlation between bits and successfully pass main statistical randomness tests.

Modeling of vertical external cavity semiconductor laser with MQW resonant structure

Numerical model is developed for modeling pulsed operation of a vertical external cavity semiconductor laser (VECSEL) with a resonant gain structure. Properties of optical modes for compound resonator formed by Bragg reflector, chip boundary and external spherical mirror were studied. For above threshold operation carrier density in each of quantum wells (QW) obeys non-linear diffusion equation with a source supplied by electron-hole pairs generated in barrier layers by pump radiation or fast electron beam. A new iteration procedure for round-trip operator evaluation was developed, which provides linear growth of computation time with the number of QWs. Results of numerical simulations are reported for a VECSEL comprising 25 QW in resonant configuration and the output spherical mirror with curvature radius 3 cm. Variation of distance to the external mirror is found to result in notable changes in power and optical quality of the output beam. The decisive role of gain and index non-linearity in these changes is identified. A range of values of distance to external mirror is found where iterative procedure does not converge. In another range, the resulting solution depends on the initial conditions for the iteration procedure.

Nonlinear semiconductor lasers and amplifiers for all-optical information processing

The nonlinear properties of semiconductor lasers and laser amplifiers when subject to optical injection are reviewed and new results are presented for multisection lasers, vertical cavity semiconductor optical amplifiers, and surface-emitting lasers. The main underlying material parameters are outlined and the key design approaches are discussed for both edge-emitting and vertical cavity devices. An overview of theoretical modeling approaches is discussed and a summary of key experimental results is presented. The practical use of optically injected edge-emitting and vertical cavity semiconductor lasers and laser amplifiers is illustrated with examples of applications including, among others, optical logic and chaotic communication.

Bistable vertical cavity laser with periodic pump modulation as a random bits generator

It is experimentally demonstrated that the semiconductor vertical cavity laser with the pump current modulation, operating in the regime of polarization bistability, can be an effective source of true random bits with the rate of generation up to several Mbps, which is determined by the modulation frequency. The generated sequences are characterized by the low bias and low correlations between generated bits.

Potential of InGaAs/GaAs Quantum Dots for Applications in Vertical Cavity Semiconductor Optical Amplifiers

The use of InGaAs/GaAs quantum dots (QDs) in vertical cavity semiconductor optical amplifiers (VCSOAs) is proposed and analyzed. The results underline the distinctive differences between practical designs for QD vertical cavity semiconductor lasers and QD-VCSOAs. By means of a QD rate-equation scheme that accounts for both homogeneous and inhomogeneous broadening and the VCSOA cavity characteristics, the effects of material properties are identified. The design routes outlined here ensure the suitability of QD-VCSOAs for high-speed applications (>100 Gb/s) that rely on the fast carrier dynamics.

Square-wave switching by crossed-polarization gain modulation in vertical-cavity semiconductor lasers

We study experimentally and theoretically the effects of crossed-polarization reinjection (XPR) on the output characteristics of a vertical-cavity semiconductor laser. We find a set of parameters values for which each polarization component develops a square-wave modulation at a period close to twice the reinjection delay. We analyze the regularity of this modulation in terms of the laser pumping current and of the reinjection level. These observations are numerically reproduced within the spin-flip model modified to account for XPR. In particular, the degradation of the square-wave switching is linked to the finite value of the spin-flip rate, and it occurs when the current approaches the boundaries of polarization bistability.

Time-Domain Vertical-External-Cavity Semiconductor Laser Simulation

A time-domain simulator for vertical external cavity semiconductor lasers (VECSEL) is described in detail. The core of the model employs a digital filter method to model the optical properties of the active mirror over a wide range of frequencies, temperatures, and carrier densities. The method is also applicable without modifications to the time-domain simulation of semiconductor saturable mirrors (SESAM). As an illustration, ultrashort pulse generation is simulated in two kinds of devices: in a synchronously pumped VECSEL and in a laser passively mode-locked by SESAM.

Quantum design of semiconductor active materials: laser and amplifier applications

AbstractWe present an overview of a novel first‐principles quantum approach to designing and optimizing semiconductor quantum‐well material systems for target wavelengths. Using these microscopic inputs as basic building blocks we predict the light‐current (LI) characteristic for a low power InGaPAs ridge laser without having to use adjustable fit parameters. Finally we employ these microscopic inputs to develop sophisticated simulation capabilities for designing and optimizing end packaged hi gh power laser structures. As an explicit example of the latter, we consider the design of a vertical external cavity semiconductor laser (VECSEL).

Positioning cavity solitons with a phase mask

Nonlinear interaction between a coherent electric field and a semiconductor medium inside a high Fresnel number cavity may give rise to the formation of cavity solitons. It is theoretically predicted that the position of these structures, mutually independent and bistable, can be controlled by gradients in the injection beam. Using a liquid crystal light valve to spatially modulate the phase of a coherent beam injected into a broad area vertical cavity semiconductor laser, the authors create reconfigurable arrays of cavity solitons. Fast time scales associated with semiconductor lasers and plasticity of localized structures suggest their potential for optical data processing.

Cavity solitons in a driven VCSEL above threshold

We experimentally demonstrate the existence and the control of cavity solitons in externally driven vertical-cavity semiconductor lasers above threshold. A model including material polarization dynamics is used to predict and confirm the experimental findings.

Comparison of possible implementations of nonmechanical optical beam steering using phased arrays of vertical cavity lasers and amplifiers

AbstractWe theoretically study the far‐field pattern of vertical‐cavity semiconductor laser (VCSEL) arrays and vertical cavity amplifier/modulator arrays. A comparison is made between the laser and amplifier array for the purpose of nonmechanical optical beam steering. The amplifier/modulator array shows superior potential over the laser arrays. The realisation of practical devices depends on the fabrication technology. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 772–775, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21471

Integrated passive wavelength athermalisation for vertical-cavity semiconductor laser diodes

The ITU G.694.2 CWDM wavelength grid spacing is largely determined by an allowance for source wavelength drift. A method of reducing this is introduced by stabilising the optical length of a short semiconductor laser cavity, using the phase contribution of DBR reflectors to compensate the increase in its optical length with temperature. It is shown that it is necessary to adopt a VCSEL design incorporating optical polymers in air-gap DBRs. Giving consideration to the technical problems of such an approach, a design procedure is developed based on a TMM survey of the available DBR design space. An example design for a 1/spl lambda/ InP cavity is shown to reduce temperature drift of the design wavelength of 1320 nm to -4.3 pm/ /spl deg/C over the range 0-80/spl deg/C.

Feedback induced polarisation switching in vertical cavity surface emitting lasers

We analyse the behaviour of a bistable vertical cavity semiconductor laser under the influence of optical feedback. Without feedback, this laser emits either vertically or horizontally polarised light with a region where polarisation bistability is observed. In this paper, we show that weak optical feedback can induce polarisation switching regardless of the polarisation of the re-injected light. These switches are quite similar to those observed in the current noise induced case. However, remarkable differences appear in the probability distribution of switching times depending on the polarisation state of the re-injected light. Experimental results detailing these differences are presented and the possible contributing mechanisms discussed.

Multilevel behavioral simulation of VCSEL-based optoelectronic modules

The assembly within a single optoelectronic interconnect module of different components, including vertical-cavity semiconductor lasers and photodiode arrays, optical fibers, and electronics implying electrical, optical, mechanical, and thermal interactions, introduces new constraints in the conception phase and necessitates a new and different approach for modeling and simulation. A promising solution, when conceiving optoelectronic microelectromechanical systems, is obtained by simulation with the multilevel language VHDL-AMS based on system component parameters and standards.