Vertical Cavity Surface Emitting Laser Laser Research Articles

Ultra high reach optical fiber systems based on CW laser and VCSEL laser operation performance signature

Abstract This study presented the possibility of the hybrid cooperation between continuous wave laser (CW) laser and vertical cavity surface emitting laser (VCSEL) laser operation performance signature for upgrading ultra high reach optical fiber systems. The total estimated lighted power spectrum configuration is simulated with wavelength ranges from 1.543 to 1.555 μm. Total estimated lighted power spectrum configuration is studied with spectral time variations. Total estimated lighted power spectrum is indicated and measured after fiber system length. The total electrical modulated signal amplitude spectrum variations are demonstrated with threshold value after receiver side. The total signal/noise modulated spectrum signal configuration is clarified with time after receiver side. Total estimated electronic power spectrum is measured and tested after receiver system. Also, the total estimated electronic power spectrum configuration is demonstrated with spectral frequency ranges from 200 to 800 GHz.

High Temperature Measurement with Low Cost, VCSEL-Based, Interrogation System Using Femtosecond Bragg Gratings.

In this article, a cost-effective and fast interrogating system for wide temperature measurement with Fiber Bragg Gratings is presented. The system consists of a Vertical Cavity Surface Emitting Laser (VCSEL) with a High Contrast Grating (HCG)-based cavity that allows for the fast tuning of the output wavelength. The work focuses on methods of bypassing the limitations of the used VCSEL laser, especially its relatively narrow tuning range. Moreover, an error analysis is provided by means of the VCSEL temperature instability and its influence on the system performance. A simple proof of concept of the measurement system is shown, where two femtosecond Bragg gratings were used to measure temperature in the range of 25 to 800 °C. In addition, an exemplary simulation of a system with sapphire Bragg gratings is provided, where we propose multiplexation in the wavelength and reflectance domains. The presented concept can be further used to measure a wide range of temperatures with scanning frequencies up to hundreds of kHz.

Geometric-phase-lens collimated vertical-cavity surface-emitting laser turned on Rb D1 line for miniature atomic magnetometers

We report on the geometric-phase-lens collimation of commercially available vertical-cavity surface-emitting laser (VCSEL), performed in the Rb D1 line spectroscopy experiments. The geometric-phase-lens (GP lens) is fabricated by the direct-write approach and employed photo-patterned liquid crystals in thin films to control the geometric phase shift. It generates the positive and negative first-order diffraction of laser beam, which are spatially separated to two focal points with one focused and the other one defocused. The Diffraction efficiency at 794.9 nm is up to 99 %. Changing the polarization state of the incident VCSEL laser continuously, the collimation and polarization conversion of divergent VCSEL laser is accomplished via GP lens. The σ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> and σ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> components of circularly polarized light are separated via different diffraction orders, which suppresses the light shift in atomic atoms. Then a compact atomic magnetometer is constructed based on a Rb micro-cell. High sensitivity up to 30 fT/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> is achieved in the single-beam configuration. It’s expected that directly fabricating the liquid crystal film on the surface of vapor cells can further reduce the sensor volume. This work extends integrated photonics to atomic spectroscopy and spin-based sensing and of great significance to promote the application of miniature atomic magnetometers in biomagnetic measurements.

Ultra-narrow linewidth characteristics of 795-nm subwavelength grating-coupled cavity vertical cavity surface emitting laser

In this paper, the 795-nm vertical cavity surface emitting laser (VCSEL) with sub-wavelength grating coupled cavity is proposed and designed based on the theory of resonant coupled cavity, and the mechanism of multi-cavity coupling linewidth narrowing and influencing factors are analyzed in detail by using the COMSOL software finite element method. The analysis results show that when photonic resonance takes place in a multi-coupled cavity, the grating-coupled cavity with reasonable design parameters and the multi-coupled cavity formed by precisely controlled lasers are phase-matched, which greatly strengthens the narrowing effect of the spectral linewidth resonance, and a 795-nm VCSEL laser with high beam quality and ultra-narrow linewidth output is obtained, finally. Theoretical results display that the reflection spectrum cold cavity linewidth Δλc of the coupling cavity with a thickness of 180nm of the spacer layer can reach 7 pm, which lays a theoretical foundation for achieving a kHz-level spectral linewidth output of VCSEL lasers.

Liquid crystal tunable vertical cavity surface emission laser with inner cavity sub-wavelength grating

With the rapid development of information technology, a wavelength-tunable vertical cavity surface emitting laser (VCSEL) is urgently needed as an optical signal source in dense wavelength division multiplexing (DWDM). Liquid crystal tunable VCSEL realized by utilizing the birefringence characteristics of liquid crystal has the advantages of stable polarization, high reliability, continuous wavelength tuning. In this paper, a liquid crystal tunable VCSEL structure based on intracavity sub wavelength grating is designed, and the influence of liquid crystal layer and sub wavelength grating on the wavelength tuning characteristics of VCSEL are analyzed and studied in depth. The results show that the thickness of the liquid crystal layer in the tunable VCSEL structure not only affects the wavelength tuning range, but also determines the mode hopping in the tuning process. In addition, an effective refractive index antireflection layer is formed by designing the subwavelength grating structure, and the refractive index difference between the liquid crystal layer and the semiconductor layer is optimized to further improve the wavelength tuning range and tuning efficiency. When the center wavelength is 980 nm, the tuning range is increased by 42%, reaching 41 nm, and the wavelength tuning efficiency is increased by 41%. It provides a new method of designing the VCSEL laser with high beam quality and continuous wavelength tuning.

Thermal characteristics of surface liquid crystal vertical cavity surface emitting laser arrays

In recent years, with the increase of information processing capacity of optical networks and the continuous improvement of high-density optical communication technology, the requirements for the performance of light sources are also increased. High-quality VCSEL with beam polarization stability control plays an increasingly important role in the above fields. The combination of liquid crystal and vertical cavity surface emitting laser (VCSEL) array can realize wavelength tunability and precise polarization control. At the same time, the introduction of liquid crystal will also change the thermal characteristics of VCSEL array. In this paper, the structure of VCSEL array is designed and the experimental research on the thermal characteristics of VCSEL array is carried out. The effects of nematic liquid crystal layer on the thermal characteristics of VCSEL array are compared and analyzed. The experimental results show that the threshold current temperature change rate of 1 × 1, 2 × 2 and 3 × 3 surface liquid crystal VCSEL array can be reduced by 23.6% and the thermal resistance can be reduced by 26.75%. Moreover, the saturated optical power of VCSEL array can be improved to a different degree. Meanwhile, the liquid crystal layer can effectively increase the heat transverse conduction and reduce the optical hole. The temperature difference between the light outlet and the table makes the heat conduction time very short at a small distance between the light outlet and the table, which is more conducive to the uniform temperature distribution of the laser array. The experimental results show that the temperature difference between the light outlet and the surrounding is less than 0.5 ℃. To sum up, the introduction of liquid crystal layer into VCSEL array not only greatly accelerates the thermal diffusion of laser array unit, but also reduces the junction temperature of active region, improves the thermal characteristics of VCSELs laser array, and lays a good theoretical and experimental foundation for realizing the high beam quality single polarization wavelength controllable VCSEL laser array.

Polar Polarization Mode and Average Radical Flux Intensity Measurements Based on All Optical Spatial Communication Systems

Abstract This study presents the polar polarization mode and average radical intensity flux distribution measurements based on all optical spatial communication systems. The numerical technique that is applied with the simulation model is the diffraction fast Fourier integral transform. Spatial optical sources are used such as continuous wave (CW) laser and vertical cavity surface-emitting laser (VCSEL) with spatial connector and spatial aperture. Spatial temporal polarization effects are taken into account. Percentage encircled flux/average flux radical intensity and polar radical polarization are measured with spatial connector distance and spatial aperture width. The encircled flux is constant at 95 % of its value in the case of VCSEL laser source at a radical distance of exactly 10 μm. However, the encircled flux is constant at 92 %of its value in the case of CW laser source at a radical distance of exactly 6 μm. It is noticed that the encircled flux increases with increasing radial distance of spatial apertures that are used with two suggested light sources. The encircled flux is constant at 93 % of its value in the case of VCSEL laser source at a radical distance of exactly 10 μm.

Optoelectronic properties of vertical-cavity surface-emitting laser at low temperature

The vertical-cavity surface-emitting laser (VCSEL) is usually used as an 850nm short wavelength source for short-distance optical interconnection at normal temperature. In this study, the characterization of the VCSEL at low temperature was mainly studied. The laser spectra and the &lt;i&gt;P&lt;/i&gt;-&lt;i&gt;I&lt;/i&gt;-&lt;i&gt;V&lt;/i&gt; curves are obtained with direct current and pulse current with 10% duty-cycle at different temperatures. It indicates that the VCSEL can work at 10K temperature environment. When the VCSEL laser is driven by direct current in a temperature range from 295 K to 10 K, the central wavelength of the laser is first red-shifted and then blue-shifted due to the change of environmental temperature and thermal effect on the device. With a pulsed-current driven source, the smaller the duty cycle, the less the heat generated by the device will be. The laser spectrum shows a blue-shift trend in the cooling process. The spectral width remains approximately stable in the cooling process. With temperature decreasing, the laser threshold current increases, and the lower the temperature, the larger the threshold current will be. It shows that the cavity mode and the gain spectrum shift with temperature changing. The cavity mode and the gain spectrum both shift to red with temperature increasing, and they shift to blue with temperature decreasing. But their shifting speeds are different. The mismatch between the cavity mode and the gain curve causes the device to need more energy for lasing. So the laser will work at a higher current driven at low temperature. The laser can work at low temperature as a stable light source. Therefore, the VCSEL has potential applications in optical interconnection system as a source at low temperature.

0.52-11.86 Gbit/s OFDM modulation for power-sharing VLC transmission by using VCSEL laser.

In this paper, we propose employing a 682 nm vertical-cavity surface-emitting laser (VCSEL) with 1 GHz bandwidth for high-speed and power-sharing wireless visible light communication (VLC) in the different transmission distances of 2 to 5 m. In the measurement, the data rate of 0.52 to 11.86 Gbit/s (0.44 to 10.8 Gbit/s in a net data rate) can be achieved by using spectral-efficient orthogonal frequency division multiplexing (OFDM) modulation with bit-loading algorithm. Therefore, 4- to 256-quadrature amplitude modulations (QAMs) are employed simultaneously in the modulation bandwidth for VCSEL-based VLC. The proposed power-sharing VLC system can be divided to four end-users, when three beam splitters (BSs) are used simultaneously. Moreover, all of the measured bit error rates (BERs) are below the forward error correction (FEC) threshold (BER = 3.8 × 10-3).

Lasing from active optomechanical resonators.

Planar microcavities with distributed Bragg reflectors (DBRs) host, besides confined optical modes, also mechanical resonances due to stop bands in the phonon dispersion relation of the DBRs. These resonances have frequencies in the 10- to 100-GHz range, depending on the resonator’s optical wavelength, with quality factors exceeding 1,000. The interaction of photons and phonons in such optomechanical systems can be drastically enhanced, opening a new route towards the manipulation of light. Here we implemented active semiconducting layers into the microcavity to obtain a vertical-cavity surface-emitting laser (VCSEL). Thereby, three resonant excitations—photons, phonons and electrons—can interact strongly with each other providing modulation of the VCSEL laser emission: a picosecond strain pulse injected into the VCSEL excites long-living mechanical resonances therein. As a result, modulation of the lasing intensity at frequencies up to 40 GHz is observed. From these findings, prospective applications of active optomechanical resonators integrated into nanophotonic circuits may emerge.

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

Hydrogen Detection Using a Functionalized Photonic Crystal Vertical Cavity Laser

A thin layer of palladium (Pd) was deposited on the surface of an etched air hole photonic crystal (PhC) vertical cavity surface emitting laser (VCSEL) to form a hydrogen gas (H2) sensor. H2 reacts with Pd, forming PdHx, which induces a shift in the complex refractive index. With Pd on its surface, the reflectivity of the top distributed Bragg reflector depends on the H2 concentration. We present device operation theory and experimental results showing a 60% output power increase and a 52 pm redshift of the lasing wavelength at 4% H2. Since the PhC VCSEL laser is single mode and the wavelength shift is comparable to the laser linewidth, the sensor can provide an accurate quantification of the H2 concentration over the range of 0-4% H2.

Stochastic Characterization and Models to Predict Performance Uncertainty in Photonic Packages

There is considerable uncertainty in the prediction of performance of a system, due mainly to idealizations in geometry, material behavior, and loading history. Uncertainties in geometry can be predicted and controlled using tighter tolerances. However, the models currently used to describe material behavior are mostly deterministic. To predict the coupling efficiency of a photonic system to a greater degree of confidence, stochastic analysis procedures are necessary. As part of such an analysis, the behavior of materials must be stochastically characterized. In this paper, we present extensive experimental data on thermally and UV-cured epoxies, typically used in photonic packages to enable stochastic analysis. We perform dynamic mechanical analysis over a wide frequency and temperature range to determine the viscoelastic behavior of the epoxies. We next derive an analytical description of the time-dependent behavior of a vertical cavity surface emitting laser (VCSEL) array bonded to a substrate. We further characterize the variation in the displacement of the VCSEL array due to the stochastic, viscoelastic behavior of the bond epoxy. We carry out Monte Carlo simulation to predict the uncertainty in the coupling efficiency of a generic photonic package. We finally relate the size of the VCSEL laser array to its ability to achieve the required coupling efficiency.

Investigation of Indium Tin Oxide (ITO) films for the VCSEL laser with dielectric Bragg reflectors

This paper investigates ITO films for the VCSEL (vertical cavity surface emitting laser) lasers emitting at 1000 nm band. Looking for low-resistance VCSEL structures a new laser with dielectric distributed Bragg reflectors (DBR) and ITO films was designed. Here we examine the influence of deposition process parameters on the optical and electrical parameters of ITO films. These films were deposited using the dc magnetron sputtering system with In2O3/SnO2 (90/10) source. After annealing at 500 °C, the transmittance of tested ITO films was in the range of 84%–98% for the 1000 nm wavelength, whereas the resistivity of all samples of the order of tens of μΩcm. The refractive index of ITO films, measured for 1000 nm, does not depend on the partial pressure of argon and oxygen, but depends on the deposition rate. For 180 nm/min deposition rate the refractive index is about 2, whereas for 70 nm/min – only 1.75. Surface of ITO films was smooth (roughness Ra is of the order of several tens of Å). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

VCSEL electrical packaging analysis and design guidelines for multi-GHz applications

The introduction of the vertical cavity surface emitting laser (VCSEL) diode structure has created the need for enhanced performance, low cost, optical packages capable of supporting data rates as high as 5 Gb/s. The popular laser packages, such as the TO-46 and the TO-56 "cans", which have been traditionally used for edge emitting laser diodes at much lower frequencies, cannot support this dramatic increase in data rates. Package parasitics and severe impedance discontinuities, inherent in the TO-46 and TO-56, impose stringent frequency limitations and dramatically effect the integrity of the electrical signals. Because electrical waveform control is essential for proper laser diode operation, these high frequency performance problems must be identified and overcome. This paper will describe electromagnetic and SPICE modeling techniques which were used to create equivalent circuits of the TO-36 and the TO-56 cans for comparison to measured results to achieve model verification. Subsequently, the models were used to determine frequency limitations associated with the TO-46 and the TO-56 laser cans. Additionally, the specific problems associated with the operation of a VCSEL laser package operating at high frequencies (i.e. >1 Gb/s) were identified; possible solutions for typical driving configurations were then developed. The lessons learned from the analysis of the TO-46 and TO-56 cans were used to determine a rudimentary set of VCSEL package design guidelines. Finally, these guidelines were used to design and model a conceptual VCSEL laser package, dubbed optical package for advanced lasers (OPAL), capable of operation to data rates as high as 5 Gb/s. The modeling techniques used to match the TO-46 and the TO-56 time domain and frequency domain simulations to measurements were extrapolated to create a model of OPAL, and to evaluate it at high frequencies.