M.-C. Amann

Surface micromachined tunable 1.55 μm-VCSEL with 102 nm continuous single-mode tuning

For the first time a vertical-cavity surface-emitting laser (VCSEL) with a single-mode wavelength-tuning over 102 nm in the range of 1550 nm is demonstrated. The fiber-coupled optical output power has a maximum of 3.5 mW and is > 2 mW over the entire tuning range. The sidemode suppression ratios are > 45 dB. The wavelength tuning is achieved with the micro-electro mechanical actuation of a mirror membrane fabricated with surface micro-machining for on-wafer mass production. The mirror membrane consists of low cost dielectric materials (SiOx/SiNy) deposited with low temperature (< 100°C) Plasma Enhanced Chemical Vapor Deposition (PECVD).

1.55-

Monolithically integrated long-wavelength vertical-cavity surface-emitting laser arrays of 4, 8, and 12 high-speed devices are presented. These devices have a lithographically defined pitch of 250 μm and feature a per-channel bandwidth of 10 Gb/s over 20 km of standard single-mode fiber. The output performance is very homogenous for the whole array. Emission wavelength is addressable by current-tuning without any bit-error-rate penalty. This allows highly scalable bandwidth for metro-range networks. Through the migration from coarse wavelength-division-multiplexed (WDM) to dense WDM operation, a bandwidth upgrade from 2.5 to 80 Gb/s is feasible without any further investment into the transmitter infrastructure.

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Molecular-beam-epitaxy-grown InGaAlAs-InP vertical-cavity surface-emitting lasers with buried tunnel junction for 1.55-/spl 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).

m VCSEL Arrays for High-Bandwidth WDM-PONs

Abstract We present a novel two-chip concept for micro-electro-mechanically tunable vertical cavity surface emitting lasers (VCSELs) for the 1.55 μm wavelength range. The VCSEL is composed of two chips: one mirror membrane chip with a movable curved mirror membrane that can be displaced by electro-thermal actuation to adjust the cavity length and one “half-VCSEL” chip consisting of a fixed bottom mirror and an amplifying active region. The possibility of separate optimization of the micro-mechanical part and the VCSEL amplifier is the main advantage of that concept, which is appropriate for photo-pumping as well as for an electrical pumping scheme. The measurement results of an optically pumped VCSEL with more than 0.5 mW continuous wave (CW) single mode output power at room temperature over a 24 nm tuning range prove the feasibility of the proposed concept.

10-Gb/s data transmission using BCB passivated 1.55-/spl mu/m InGaAlAs-InP VCSELs

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 characteristics in dependence on the bias of the VCSEL are investigated. It is determined that the tuning range saturates by increasing the current of the VCSEL and a further increase causes a multimode behavior within the tuning range.

A new concept for tunable long wavelength VCSEL

Vertical-cavity surface-emitting lasers (VCSELs) at 1.55 mum provide high modulation bandwidth and low attenuation at a low cost. Like other directly modulated lasers, laser chirp limits the link length in standard single-mode fibers at high data rates and fiber dispersion causes bit-error-rate (BER) penalty. This can be overcome by dispersion-compensating fibers (DCFs). This letter investigates the modulation performance of monolithically grown 1.55-mum VCSELs utilizing a DCF to boost the possible link length. Data-transmission experiments are performed at 10 Gb/s and dispersion-dependent BER performance is presented for the first time for this type of laser.

Bulk-Micromachined VCSEL At 1.55

GaInAsSb-GaSb strained quantum-well (QW) ridge waveguide diode lasers emitting in the wavelength range from 2.51 to 2.72 mum have been grown by molecular beam epitaxy. The devices show ultralow threshold current densities of 44 A/cm2 (L rarr infin) for a single QW device at 2.51 mum, which is the lowest reported value in continuous-wave operation near room temperature (15degC) at this wavelength. The devices have an internal loss of 3 cm-1 and a characteristic temperature of 42 K. By using broader QWs, wavelengths up to 2.72 mum could be achieved.

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InP-based vertical-cavity surface-emitting lasers (VCSELs) at 1.55-mum emission wavelength with improved modulation bandwidth and temperature behavior are demonstrated. Utilizing an improved active region, thermal design, and reduced chip parasitics, a superior modulation-bandwidth >10 GHz is achieved up to 85degC. The new VCSEL device is compared in detail with our reference design, analyzing all bandwidth-limiting elements. With their improved temperature range at invariant output power and minimal threshold change with temperature these VCSELs are especially qualified for uncooled operation in passive optical networks. Potential bit rates of 12.5 or even 17 Gb/s are expected with this kind of devices for cost-effective 100-G Ethernet solutions at metro-range.

m With 76-nm Single-Mode Continuous Tuning Range

Excellent lasing performance is demonstrated for a 1.83-/spl mu/m InGaAlAs-InP vertical-cavity surface-emitting laser (VCSEL) utilizing the buried tunnel junction technology. Threshold currents as low as 190 /spl mu/A at 20/spl deg/C and operating temperatures as high as 90/spl deg/C have been measured. These values are the best ones reported so far for long-wavelength VCSELs.

1.55-

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.