A vertical-cavity surface emitting laser (VCSEL) was invented 30 years ago. A lot of unique features can be expected, such as low-power consumption, wafer-level testing, small packaging capability, and so on. The market of VCSELs has been growing up rapidly in recent years, and they are now key devices in local area networks using multimode optical fibers. Also, long wavelength VCSELs are currently attracting much interest for use in single-mode fiber metropolitan area and wide area network applications. In addition, a VCSEL-based disruptive technology enables various consumer applications such as a laser mouse and laser printers. In this paper, the recent advance of VCSEL photonics will be reviewed, which include the wavelength extension of single-mode VCSELs and their wavelength integration/control. Also, this paper explores the potential and challenges for new functions of VCSELs toward optical signal processing

https://cnst.nctu.edu.tw/mbe08/abstract/6-13.30-14.00-koyama.pdf

Recent Advances of VCSEL Photonics

The intensive investment in optical microelectromechanical systems (MEMS) in the last decade has led to many successful components that satisfy the requirements of lightwave communication networks. In this paper, we review the current state of the art of MEMS devices and subsystems for lightwave communication applications. Depending on the design, these components can either be broadband (wavelength independent) or wavelength selective. Broadband devices include optical switches, crossconnects, optical attenuators, and data modulators, while wavelength-selective components encompass wavelength add/drop multiplexers, wavelength-selective switches and crossconnects, spectral equalizers, dispersion compensators, spectrometers, and tunable lasers. Integration of MEMS and planar lightwave circuits, microresonators, and photonic crystals could lead to further reduction in size and cost

/pdf/optical-mems-for-lightwave-communication-53kgmfd364.pdf

Optical MEMS for Lightwave Communication

Vertical-cavity surface-emitting lasers (VCSELs) are now key optical sources in optical communications. Their main application is currently in local area networks using multimode optical fibers. VCSELs are also being rapidly commercialized for single-mode fiber metropolitan area and wide area network applications. The advantages of VCSEL include simpler fiber coupling, easier packaging and testing, and the ability to be fabricated in arrays. In addition, VCSELs have an inherent single-wavelength structure that is well suited for wavelength engineering. All these advantages promise to lead to cost-effective wavelength-tunable lasers, which are essential for the future intelligent, all-optical networks. The author reviews the advances on wavelength-tunable VCSELs. She summarizes some of the early breakthroughs in wavelength engineering of VCSELs and then concentrates on the designs and properties of micromechanical tunable VCSEL.

Tunable VCSEL

This invention generally relates to one or more computer networks having computers like personal computers or network servers with microprocessors linked by broadband transmission means and having hardware, software, firmware, and other means such that at least one parallel processing operation occurs that involve at least two computers in the network. More particularly, this invention relates to one or more large networks composed of smaller networks and large numbers of computers connected, like the Internet, wherein more than one separate parallel processing operation involving more than one different set of computers occurs simultaneously and wherein ongoing processing linkages can be established between virtually any microprocessors of separate computers connected to the network. Still more particularly, this invention relates to business arrangements enabling the shared used of network microprocessors for parallel and other processing, wherein personal computer owners provide microprocessor processing power to a network, preferably for parallel processing, in exchange for network linkage to other personal and other computers supplied by network providers, including linkage to other microprocessors for parallel or other processing; the basis of the exchange between owners and providers being whatever terms to which the parties agree, subject to governing laws, regulations, or rules, including payment from either party to the other based on periodic measurement of net use or provision of processing power.

Global network computers

Technologies now exist for implementing dense surface-normal optical interconnections for silicon CMOS VLSI using hybrid integration techniques. The critical factors in determining the performance of the resulting photonic chip are the yield on the transceiver device arrays, the sensitivity and power dissipation of the receiver and transmitter circuits, and the total optical power budget available. The use of GaAs-AlGaAs multiple-quantum-well p-i-n diodes for on-chip detection and modulation is one effective means of implementing the optoelectronic transceivers. We discuss a potential roadmap for the scaling of this hybrid optoelectronic VLSI technology as CMOS linewidths shrink and the characteristics of the hybrid optoelectronic transceiver technology improve. An important general conclusion is that, unlike electrical interconnects, such dense optical interconnections directly to an electronic circuit will likely be able to scale in capacity to match the improved performance of future CMOS technology.

/pdf/scaling-optoelectronic-vlsi-circuits-into-the-21st-century-a-bi3r37y043.pdf

Scaling optoelectronic-VLSI circuits into the 21st century: a technology roadmap

Fabry-Perot microinterferometer is demonstrated that combines a GaAs-AlAs vertical cavity with a suspended movable membrane. Electrostatic displacement of the gold/silicon nitride membrane allows for broad and continuous wavelength tuning of the cavity resonance formed by the combination of the GaAs cavity and the air gap below the membrane. The device exhibits a 32-nm tuning range around the 920-nm center wavelength for 0-14 V applied bias and FWHM linewidths near 3 nm; this corresponds to membrane deflections of up to 0.27 /spl mu/m. Such structures provide the foundation for wavelength selective photodiodes, light emitters, and lasers in which the active wavelength is under voltage control. >

Vertical coupled-cavity microinterferometer on GaAs with deformable-membrane top mirror

A microlaser is described which is electrostatically tunable. One of the reflectors includes at least one reflecting part whose distance from the other reflector can be adjusted to change the effective optical distance between the reflectors and thus tune the optical frequency at which lasing occurs. The disclosure brings out that the inventive aspect is also applicable to other optical devices having reflectors defining a Fabry-Perot cavity. An optical interconnecting scheme for processors using the microlaser is also described.

Electrostatically tunable optical device and optical interconnect for processors

We show theoretically that the maximum modulation ratio in Fabry–Perot reflective electroabsorption modulators for a given insertion loss is solely a function of the ratio of the maximum to minimum absorption. We increase this ratio by using thinner quantum wells than are conventionally used and obtain significantly improved performance. We obtain an insertion loss of 1.2 dB and a modulation ratio of 7.5 with a 5 V operating bias.

Optimization of modulation ratio and insertion loss in reflective electroabsorption modulators

The invention relates to an apparatus including a semiconductor grating whose optical properties can be changed electrically in order to steer a diffracted laser beam with no moving parts. Lithographically defined portions, stripes or areas formed in a semiconductor quantum well region used in association with selectable voltage supply means enable control of the optical characteristics of the grating. The optical properties of the semiconductor quantum well region vary in response to variations in voltage applied to the areas which in turn change the transmissivity or reflectivity of the areas. By selectively applying voltages, the diffraction pattern obtained in the far-field from illuminating the areas is thus controlled and beam steering results. By using a two-dimensional array of areas, or alternatively using two such one dimensional arrays, beam steering in two dimensions may be accomplished. Using a Fabry-Perot cavity allows large reflectivity changes to occur from the absorption changes, and another external Fabry-Perot cavity increases the optical power steered into the diffracted modes. Electronically addressing a large number of areas can be achieved using a number of standard methods.

Dynamic optical grating device

We demonstrate a novel approach to the molecular beam epitaxial (MBE) growth of vertical Fabry–Perot cavities with quarter‐wave mirrors. At two selected points, the growth is interrupted and the reflectivity spectrum is measured without removing the wafer from the vacuum system. Corrections are then made in the growth of subsequent layers. By making measurements on the incomplete structure, separate corrections can be made to center both the mirror reflectivity and the cavity resonance at the desired wavelength. We present theoretical and experimental data demonstrating the effectiveness of the approach, and estimate the effects on device performance.

B. Pezeshki

Papers

Vertical coupled-cavity microinterferometer on GaAs with deformable-membrane top mirror

Electrostatically tunable optical device and optical interconnect for processors

Optimization of modulation ratio and insertion loss in reflective electroabsorption modulators

Dynamic optical grating device

Molecular beam epitaxy growth of vertical cavity optical devices with in situ corrections