An extensive characterization of the spectral properties of a largely tunable laser in the 1.56-μm spectral range is reported. This device combines a vertical-cavity surface-emitting laser (VCSEL) with a micro-machined (MEMS) Bragg mirror in a very compact arrangement. The large tunability obtained by an electro-thermal actuation of the MEMS mirror makes this device very attractive for high-resolution spectroscopy. Relevant laser parameters for the implementation of wavelength modulation spectroscopy techniques in gas sensing, such as tuning and modulation properties, are presented. A preliminary gas spectroscopy experiment performed with this laser is also shown.

A single-mode continuous tuning range of 76 nm is realized using a bulk-micromachined vertical-cavity surface-emitting laser (VCSEL) operating at wavelengths around 1.55 mum. The bulk-micromachined upper mirror is optimized for dielectric material and manufactured separately from the half-VCSEL. The VCSEL is tuned by an electrothermal actuation of a concave bended membrane. The tuning range charac...

The intrinsic dynamics of a micromachined tunable surface-emitting laser with buried tunnel junction are derived from amplitude modulation response and relative intensity noise. The dependence of resonance frequency on bias current and wavelength is reported.

We present a visible VCSEL with integrated beam splitter. By focusing one beam onto a moving target and monitoring the power variation in the second beam, these devices can be used as Doppler-based velocity sensors.

The effective interplay of simulation and experimental results for analysis and optimization of microelectromechanical system (MEMS)-tunable vertical-cavity surface-emitting lasers (VCSELs) operating at wavelength around 1.55 mum is presented. The VCSEL combines a MEMS with concave Al-GaAs-GaAs mirror membrane and an InP-based active cavity with tunnel junction aperture in a hybrid two-chip assembly. Using electrothermal MEMS actuation the included air-gap can be expanded and the cavity resonance can be tuned to longer wavelengths. The experimental results are compared with the theoretical results provided by VELM (VCSEL ELectroMagnetic), the efficient code based on the coupled mode model and adapted for the first time to handle curved-mirror geometries. The vectorial code is found to be able to fully reproduce the experimental results, such as device tuning range, modal frequency splitting, threshold gains and modal selectivity.

We have developed plugless optical transceivers for low cost optical networking with plastic optical fiber (POF). The transmission speed is 125 Mb/s for Ethernet applications and 1.25 Gb/s for Gigabit Ethernet and other high speed applications. The high speed modules for Gigabit transmission are based on a red VCSEL light source for the transmitter that matches the optical attenuation minimum of the plastic fiber media. The devices have demonstrated excellent reliability with more than 850,000 hours of mean-time-to-failure operating life time at elevated temperatures of 40degC. Automotive qualified, rugged resonant cavity LEDs (RCLEDs) are used for the lower speed modules. The plugless transceiver design enables the direct optical connection between the active components and standard POF without the need for special termination of the fiber. Only a simple cutting action is required. This enables low cost field installations.

There are many potential applications of visible, red (650nm - 690mn) vertical cavity surface emitting lasers (VCSELs) including high speed (Gb) communications using plastic optical fiber (POF), laser mouse sensors, metrology, position sensing. Uncertainty regarding the reliability of red VCSELs has long been perceived as the most significant roadblock to their commercialization. In this paper we will present data on red VCSELs optimized for performance and reliability that will allow exploitation of this class of VCSEL in a wide range of high volume consumer, communication and medical applications. VCSELs operating at similar to 665nm have been fabricated on 4" GaAs substrates using MOCVD as the growth process and using standard VCSEL processing technology. The active region is AlGaInP-based and the DBR mirrors are made from AlGaAs. Threshold currents are typically less than 2mA, the devices operate up to > 60C and the light output is polarized in a stable, linear characteristic over all normal operating conditions. The MB modulation bandwidth of the devices is in excess of 3GHz and we have demonstrated the operation of a transceiver module operating at 1.25Gb/s over both SI-POF and GI-POF Ageing experiments carried out using a matrix of current and temperature stress conditions allows us to estimate that the time to failure of 1 % of devices (TT1%F) is over 200,000h for reasonable use conditions - making these red VCSELs ready for commercial exploitation in a variety of consumer-type applications. Experiments using appropriate pulsed driving conditions have resulted in operation of 665nm VCSELs at a temperature of 85 degrees C whilst still offering powers useable for eye-safe free space and POF communications.

We have fabricated VCSELs in the visible red spectrum. The emission wavelength ranges from approximately 650 nm to 690 nm depending on application. The devices are grown on GaAs substrates by MOVPE and processed using standard VCSEL processing technology. The active layer consists of three InGaP quantum wells. The Bragg mirrors are AlGaAs/AlAs multilayer structures. The bottom mirror is n-doped, the top mirror is p-type doped. The threshold current of the devices is less than 2 mA. The maximum operating temperature is beyond 60degC. The optical output power is limited by eye-safety conditions to a maximum of 390 muW. The modulation bandwidth of the devices is in excess of 3 GHz even for low operating currents below 5 mA. This enables IEEE1394b S800 and Gigabit Ethernet transmission speed over POF as well as higher speed applications such as optical links for high definition TV. Any real application requires highly reliable devices and hence intensive life time testing of these red VCSELs has been undertaken. From aging test results applying various operating temperatures and currents we have inferred a conservative estimate for the activation energy of 0.6 eV. The 1%-time-to-failure (1%TTF) of the devices is over 100,000 hrs at use conditions. Continuous testing of more devices over thousands of operating hours is poised to improve reliability data further.

A fiber-based remote measurement setup for tunable diode laser absorption spectroscopy, introducing an electrically pumped, micromechanical vertical-cavity surface-emitting laser with single-mode emission spectrum, narrow linewidth of 40 MHz, and broadband, continuous wavelength coverage of 51 nm around 1.55 mum is presented. The tunable laser spectrometer is employed for analysis of heterogeneous gas compositions and simultaneous detection of two species, ammonia and carbon monoxide, in a single continuous wavelength sweep. Broadband absorbance spectra are captured at elevated temperatures up to 300 degC revealing opposed temperature dependencies for selected transitions.

Dynamic tuning characteristics of micromachined surface-emitting lasers with broadband wavelength coverage (>55nm) around 1.55 mum and up to 1.8mW singlemode power are presented. Electro-thermal actuation enables full scale wavelength switching in milliseconds with durable long-term operation.

A micromechanically tunable VCSEL with optimized cavity design for broadband tuning is presented. The laser spans a wide range (54nm) within the C- and L-band with singlemode optical power in the mW-regime and stable polarization.

We present an electrically pumped and micromechanically tunable InP-based vertical-cavity surface-emitting laser operating in the 1.55-/spl mu/m wavelength range. The current confinement is achieved by a buried tunnel junction. The GaAs-based movable top mirror membrane is fabricated separately, assembled on top of the device, and can be actuated electrothermally. A single mode output power of about 1.7 mW and a tuning range of 28 nm was obtained. By the use of an antireflection coating at the semiconductor-air-interface, we were able to extend the tuning range up to 60 nm as expected from one-dimensional simulations.

Molecular-beam-epitaxy-grown InGaAlAs-InP vertical-cavity surface-emitting lasers with buried tunnel junction for 1.55-mu m wavelength, passivated with benzocyclobutene (BCB) and coplanar contacts are presented. The devices show 3-dB modulation frequencies above 8 GHz (small signal modulation) and wide open eye diagrams up to 10 Gb/s over more than 4.6-km ITU-T G.653 fiber (data transmission experiment).

We present a micromechanically tunable long-wavelength vertical-cavity surface-emitting laser with a buried tunnel junction aperture and a stable half-symmetric cavity for full mode control. The conjunction of the active part 'half-VCSEL' and the curved MEMS-mirror in a two-chip assembly enables high output power singlemode emission exceeding 1 mW. Electrothermal actuation of the micromechanical chip allows us to extend the single wavelength performance to a continuously tunable, selectively wavelength-addressable spectrum of 28 nm. The concave curvature and the resulting long air-gap cavity are designed to favour the resonance of the fundamental mode, i.e. to match the phase front predicted by Gaussian beam theory corresponding to the aperture diameter of 10 mu m. The spatial beam profile of the MEMS-VCSEL is measured in the far-field and compared with a conventional VCSEL with a fixed plane top mirror. The polarization is controlled by a dominating mirror asymmetry. High sidemode suppression over the whole tuning range with respect to both the transverse modes (>40 dB) and the polarization modes (>30 dB) is demonstrated.

Singlemode emission exceeding 1 mW over 28 nm tuning range of an electrically pumped long-wavelength VCSEL is achieved. A tunable curved MEMS Bragg mirror enables high output power operation with sidemode suppression of more than 40 dB

The design and characterization of bulk micro-machined tunable VCSELs operating at 1.5 mum are presented. Tuning ranges of more than 20 nm with side mode suppression larger than 40 dB and output powers larger 2 mW were obtained

In this paper, we present an InP-based micromechanically tunable VCSEL emitting in the 1.55microm wavelength region with a 26nm tuning range. The laser is based on a two-chip concept, allowing for a separate optimization of the curved top mirror and the amplifying component. Current confinement is achieved by a buried tunnel junction. The design of the microcavity ensures fundamental mode operation with a side mode suppression ratio exceeding 49dB even for large apertures. Simulations indicate that the tuning range is limited by coupled cavity effects and reveal important design criteria like an upper boundary regarding the device thickness.

We present a tunable VCSEL emitting around 1.55 /spl mu/m with a maximum tuning range of 43 nm. To investigate the effects of coupled cavities within such a structure, simulations have been performed and compared to experimental results.