We demonstrate an ultra-short cavity 1.5-μm single-mode directly-modulated VCSELs with record modulation bandwidth of 22 GHz at room temperature operation.

We generate a 100-Gb/s polarization-division-multiplexed 4-level pulse-amplitude-modulation signal with two directly modulated 1.5-μm single-mode VCSELs. Coherent detection and digital signal processing enable the transmission over 400-km standard single-mode-fiber (SSMF) with 20% overhead hard-decision forward-error-correction.

We generate a 105.7-Gb/s signal by directly modulating a 1.5-µm VCSEL with a 33.35-Gbaud 3-level signal and polarization multiplexing. By using digital coherent detection, we successfully transmit the 105.7-Gb/s line rate (88.10 Gb/s net bit rate) signal over 960-km standard single-mode-fiber (SSMF) at a 20% hard-decision forward-error correction (FEC) threshold, which is at bit-error ratio (BER) of 1.5 x 10(-2)

In this paper, we present fixed-wavelength, vertical-cavity-surface-emitting lasers (VCSELs) based on InP with remarkable single-mode (SM) output powers. It is shown that a precise choice of the diameters of the ring geometry of the bottom GaInAs intracavity contact layer severely affects the guiding behavior of the fundamental and first-order modes inside the cavity. Experimental data, statistics, and theories will be discussed on how to overcome spatial hole burning and how to master thermal guiding and efficient current injection in order to extend SM output powers to beyond 8 mW at room temperature for VCSELs with 7 μm aperture. Coming along with side-mode suppression ratios exceeding 50 dB and continuous electrothermal wavelength tunings exceeding 8 nm, these laser devices define a new state of the art of electrically pumped InP-based short-cavity long-wavelength VCSELs at 1.55 μm emission.

We present polarization stable, tunable long-wavelength vertical-cavity-surface-emitting lasers (VCSELs) at 1.55 mu m based on InP. The tuning is accomplished by a two-chip membrane mounting technique denoted as bulk-micro-machining. The membrane consists of a GaAs-based distributed Bragg reflector and represents the top mirror. By its electro thermal actuation, cavity tuning occurs. This results in a continuous wavelength shift. Polarization stability is achieved by an implemented semiconductor/air subwavelength grating (SWG) written in the top-most layers of the membrane facing the VCSEL eye after mounting process. The SWG integration is realized by a combination of holographic lithography, barrel, and reactive ion etching. The manufactured micro-electro-mechanical-system SWG-VCSELs show a continuous, polarization stable wavelength tuning of similar to 25 nm with a peak optical power of 4 mW fiber-coupled in an MMF and thresholds of 3-3.5 mA.

A modal analysis of both molecular beam epitaxy (MBE)- and metal-organic vapor phase epitaxy (MOVPE)-planarized short-cavity (SC) vertical-cavity surface-emitting lasers (VCSELs) emitting at 1.3 μm is presented. The comparison of simulated threshold gains with experimental threshold current densities, as well as modal gain difference with side-mode suppression ratios, allows the clear identification of design-related limitations with respect to single-mode emission for different active diameters. In particular, the influence of the radial profile of the effective refractive index on the strength of index-guiding is found to depend on the regrowth-type (MBE or MOVPE). Moreover, the impact of strongly absorbing contact layers and surface relief structures on the modal properties of the fundamental mode is investigated. A design proposal for a MOVPE-regrown SC-VCSEL with optimized surface relief structure is given, predicting reduced threshold current densities and increased single-mode optical output powers.

The Full Services Access Network group has recently selected the time and wavelength division multiplexed passive optical network (TWDM-PON) as the base technology solution for next-generation PON stage-2 (NG-PON2). Meeting the core requirements of NG-PON2 necessitates the following additional features in the transceivers of the optical network unit (ONU) that is located at subscriber premises: (a) legacy system compliant; (b) wavelength tunable; (c) cost-efficient; and (d) energy-efficient. To address these features, we investigate the properties of short-cavity vertical-cavity surface-emitting lasers (SC-VCSELs) for implementation as colorless ONU transmitters in future TWDM-PONs. Specifically, we investigate the tunability and transmission performance of the SC-VCSEL across the C-minus wavelength band for legacy system compliance. We report on error-free transmission across a 800 GHz tuning range with a potential aggregate upstream capacity of 80 Gbps over a system reach of 40 km and with a split ratio of 1:128 per wavelength channel. Results were achieved without dispersion compensation and electronic equalization. We also evaluate the energy efficiency of the SC-VCSEL in active, doze, and sleep mode. When in active mode, the SC-VCSEL transmitter block consumes 91.7% less power than a distributed feedback (DFB) laser transmitter block. When transitioning between doze and active modes, the transmitter block has a short settling time of only 205 ns, thus increasing the power-saving duration and consequently reducing the overall power consumption of the ONU. Through numerical analysis, evaluation of the energy-savings of the SC-VCSEL ONU over the DFB ONU under various modes of operation, demonstrates up to 84% of energy-savings. The capacity, tuning range, split ratio, system reach, and energy-savings arising from SC-VCSEL ONU implementation as reported in this work, exceed the minimum requirements of NG-PON2 for future TWDM-PON deployments.

The tunability feature of short-cavity vertical-cavity surface-emitting lasers in the C-minus band to provide low-power, cost-efficient, colourless, and legacy system compliant transmitters for future time and wavelength division multiplexed passive optical networks is investigated. For the first time, a report is presented on error-free performances across a 800 GHz tuning range with a potential aggregate upstream capacity of 80 Gbit/s over a system reach of at least 40 km and with a 1:64 split ratio.

In-situ monitoring of growth parameters such as thickness and quality of InP and GaAs based materials is presented. This is a key technology for the fabrication of optoelectronic devices like VCSELs.

In this paper we present the first InP-based short-cavity Vertical-Cavity Surface-Emitting Laser with an AlGaInAsP/GaInAsP active region and a re-grown and structured GaAs0.51Sb:C/Ga0.47InAs:Si buried tunnel junction (BTJ), which serves as current aperture, grown by LP-MOVPE. We achieved over 1mW single-mode continuous-wave (cw) emission at around 1.3μm wavelength and room-temperature. The small-signal modulation bandwidth exceeds 7.5GHz, which is appropriate for 10Gb/s data transmission, and the series resistance is as low as 24Ω. The latter value indicates around three times lower dissipated power consumption than comparable MOVPE grown InP-based VCSELs.

In this paper, the enhanced high-speed performance and energy-efficiency of 1.3 μm Short-Cavity VCSEL with buried-tunnel-junction is reported. Error-free data-transmission at 30 Gb/s up to 10 km and at 25 Gb/s up to 25 km is performed at room temperature over single mode fiber. Furthermore, low energy-to-data-distance ratios of 24 fJ/(bit·km) are achieved.

The energy savings of 10 Gb/s VCSEL ONUs in sleep/doze mode operations is critically analyzed as function of polling cycle, network load, and upstream access. Results provide guidance on specific energy saving mode to maximize energy savings throughout the day.

We present the first error-free data-transmission at 30 Gb/s over up to 10 km of fiber using energy-efficient 1.3 μm short-cavity VCSELs with low threshold current of 500 μA and high conversion efficiencies up to 30%. A record-low energy-to-data-distance ratio of 27 fJ/(bit·km) is achieved for such a VCSEL-link.

We review the state-of the art of long-wavelength VCSELs. Furthermore, the short-cavity concept which has already been successfully implemented in 1.55 μm devices is extended to 1.3 μm devices resulting in excellent static and dynamic device properties. In particular, high output powers of 1.8 mW at an ambient temperature of 80 °C, high differential quantum efficiencies up to 56% and wall-plug efficiencies up to 36% at room-temperature are reported. Small-signal modulation bandwidths in excess of 15 GHz are presented. The large-signal modulation at a bit-rate of 25 Gbps is investigated.

A study on the correspondence between the voltage and optical properties of long wavelength vertical cavity surface-emitting lasers (VCSELs) during tuned optical injection is presented. A direct link between the voltage response and the induced optical dynamics for parallel and orthogonal injection is highlighted. The induced dynamics include unlocked stable polarization switching at large frequency offsets from the free-running VCSEL lasing wavelength for both injection orientations. The carrier density change during stable locking is estimated using the cavity resonance shift and voltage change. This estimate is confirmed using a full numerical simulation of the injection locked rate equations.

The energy savings of 10 Gbps vertical-cavity surface-emitting lasers (VCSELs) for use in energy-efficient optical network units (ONUs) is critically examined in this work. We experimentally characterize and analytically show that the fast settling time and low power consumption during active and power-saving modes allow the VCSEL-ONU to achieve significant energy savings over the distributed feedback laser (DFB) based ONU. The power consumption per customer using VCSEL-ONUs and DFB-ONUs, is compared through an illustrative example of 10G-EPON for Video-on-Demand delivery. Using energy consumption models and numerical analyses in sleep and doze mode operations, we present an impact study of network and protocol parameters, e.g. polling cycle time, network load, and upstream access scheme used, on the achievable energy savings of VCSEL-ONUs over DFB-ONUs. Guidance on the specific power-saving mode to maximum energy savings throughout the day, is also presented.

The use of vertical cavity surface emitting lasers (VCSELs) in energy efficient ONUs is critically examined using energy consumption models and numerical analyses of energy savings in sleep and doze mode operations. The implication of polling cycle times and network loads on the resulting energy savings and upstream utilization is investigated in the context of a 10 GE-PON with VCSEL ONUs, and for the first time, guidance on the tradeoffs between various network and protocol parameters is provided.

We experimentally demonstrate 30-Gbit/s (24.7-Gbit/s net) OFDM intensity modulation of a low-cost 1550-nm VCSEL. The optical OFDM signals transmission over 7-km G.655 SMF is also realized successfully.

The energy efficiency of short-cavity VCSELs is examined for static and dynamic device operation. Record-high modulation bandwidths beyond 18GHz, conversion efficiencies of 23% and energy-efficient large-signal modulation at 10Gbps over 17.3km fiber-line are demonstrated.

We discuss the use of energy-saving 10 Gbps vertical-cavity surface-emitting lasers (VCSELs) as optical network unit (ONU) transmitters in passive optical networks. In particular, we review the features and properties of the VCSEL that enable energy-savings to be achieved. The power consumption per customer using VCSEL-ONUs and DFB-ONUs, is compared through an illustrative example of 10G passive optical network for Video-on-Demand delivery. An impact study of network and protocol parameters on the achievable energy-savings of VCSEL-ONUs over DFB-ONUs, is presented.