C.J. Chang-Hasnain

Widely and continuously tunable micromachined resonant cavity detector with wavelength tracking

We demonstrate a resonant cavity wavelength tunable detector with a record 30-nm continuous tuning range, 17-dB extinction ratio, and a low 7-V tuning voltage. The detector map be biased to operate in one of two modes. In the first, the detector is tuned to a specific wavelength. In the second, the detector can be tuned to a nominal wavelength and remain locked to the wavelength of the incident light despite wavelength variations. Consequently, this detector is ideal for operation as a cost-effective and robust receiver for WDM communication systems, spectroscopic applications, and wavelength measurement.

Vertical-cavity surface-emitting InGaAs/GaAs lasers with planar lateral definition

A planarity preserving method for the definition of vertical‐cavity surface‐emitting lasers (VC‐SEL) is described. A strained‐layer InGaAs quantum well VC‐SEL structure was grown and lasers were laterally defined using a tailored deep proton implantation process. In these lasers we obtained low threshold current densities of 1000 A/cm2 and efficient cw operation. This method facilitates large‐scale integration of VC‐SEL devices.

Single-mode, passive antiguide vertical cavity surface emitting laser

We report the characteristics of a single-mode, low threshold, passive antiguide region (PAR) vertical cavity surface emitting laser (VCSEL) using both organometallic chemical vapor deposition (OMCVD) and molecular beam epitaxy (MBE) for the regrowth of the PAR structure. The novel passive antiguide region surrounding the active region is demonstrated to be a highly effective transverse mode and polarization mode selection mechanism. A stable single fundamental mode at high currents has been achieved experimentally for laser aperture as large as 16 /spl mu/m diameter, In addition, very low threshold current of 0.8 mA and current density of 490 A/cm/sup 2/ are achieved with 8 and 32 /spl mu/m diameter VCSELs, respectively. A detailed numerical two- and three-dimensionaI analysis was performed using the beam propagation method. The modal losses were calculated as a function of the cladding refractive index and the laser size. Quantitative results leading to approximate formulae have been achieved. The high mode selectivity obtained from the numerical analysis is in good agreement with the experimental results we have achieved. >

Wavelength‐selectable laser emission from a multistripe array grating integrated cavity laser

We report laser operation of a multistripe array grating integrated cavity (MAGIC) laser in which the wavelength of the emission from a single output stripe is chosen by selectively injection pumping a second stripe. We demonstrate a device that lases in the 1.5 μm fiber band at 15 wavelengths, evenly spaced by ∼2 nm. The single‐output/wavelength‐selectable operation, together with the accurate predefinition of the lasing wavelengths, makes the MAGIC laser a very attractive candidate for use in multiwavelength networks.

2-D WDM optical interconnections using multiple-wavelength VCSEL's for simultaneous and reconfigurable communication among many planes

A novel interconnection configuration in which one two-dimensional plane can communicate simultaneously and reconfigurably with many planes by using wavelength-division-multiplexing (WDM) is proposed and analyzed. This system incorporates arrays of multiple-wavelength vertical-cavity surface-emitting lasers (VCSELs) as well as wavelength-selective detecting planes. High signal contrast ratio with low power penalty can be achieved for a channel separation>30 nm, limited only by the detector spectral response. By using WDM pixels, the system capacity is significantly enhanced as compared to more traditional techniques.<<ETX>>

Multiple-wavelength vertical-cavity surface-emitting laser arrays with a record wavelength span

Multiple-wavelength vertical-cavity surface-emitting laser (VCSEL) arrays are fabricated using a modified patterned-substrate growth technique in a molecular beam epitaxy (MBE) system. We achieved a large lasing wavelength span of 62.7 nm and highly uniform threshold currents with an average of 2.16/spl plusmn/0.81 mA. High repeatibility of wavelength spacing between 15 arrays with sharp wavelength shift rate 117.14 nm/mm is achieved.

Electrically-pumped directly-modulated tunable VCSEL for metro DWDM applications

We report the first electrically pumped tunable VCSELs with continuous tuning in 1530-1620 nm wavelength regime. The VCSELs are directly modulated at 2.5 Gbps (OC-48) rates and show error-free transmissions. Wavelength locking to ITU-grids are accomplished in 200 /spl mu/s.

Multigigabit/s operations of 16-wavelength vertical-cavity surface-emitting laser array

A multiple-wavelength 2*8 monolithic surface-emitting laser array with a potential aggregate array capacity of 80 Gb/s is reported. The high-speed packaging for the array was made possible with a slip-chip bonding technique, and each laser was capable of 5 Gb/s operation. The chirp-broadened 20-dB spectral width was less than 0.3 mm and the spectra occupied 16 independent wavelengths. Both optical and thermal crosstalks were very small, and the electrical crosstalk ranged from <-35 dB at <1 GHz, to -10 approximately -30 dB at 5 GHz.<<ETX>>

Multiple-wavelength vertical cavity laser arrays on patterned substrates

We demonstrate a spatially chirped resonant wavelength in vertical cavities and vertical cavity surface emitting lasers (VCSELs) grown by Molecular Beam Epitaxy. The wavelength shift is achieved by varying the GaAs growth rate across the wafer using a patterned backing substrate to induce a lateral temperature profile. Temperature patterns transfer to thickness patterns with a resolution on the millimeter scale. We demonstrate 8-nm periodic cavity mode shifts in GaAs-AlAs Fabry-Perot vertical cavities, and a 20-nm shift in lasing wavelength in a VCSEL array. >

A novel all-optical self-routed wavelength-addressable network (SWANET)

A novel all-optical self-routed wavelength-addressable network based on a new multiwavelength routing protocol is proposed. A distributed switching network that uses a low-speed routing header provides a transparent path for the high-speed data while utilizing low-speed electronic processing of the routing header. Each data packet is preceded by a routing header composed of a serial combination of wavelengths. The number of destination addresses is dramatically increased over conventional wavelength-division multiplexing or conventional photonic packet switching networks for the same number of wavelengths or header digits, respectively. A 1/spl times/4 switching node is implemented demonstrating the switching and transmission capabilities of this wavelength-addressable network.<<ETX>>