Wupen Yuen

Long wavelength-tunable VCSELs with optimized MEMS bridge tuning structure

In this letter, we present the first demonstration of a long wavelength-tunable vertical-cavity surface-emitting laser (VCSEL) using a monolithically integrated bridge tuning microelectromechanical system structure. The use of such a tuning structure allows for better wavelength tuning repeatability and wider tuning range as compared to cantilever-based tunable VCSELs. The devices show tuning ranges over 22 nm with peak output power of 1.3 mW in continuous-wave operation at 15/spl deg/C. The bridge structure has a mechanical resonant frequency of 80 kHz. The transmission test through 300-km single-mode fiber (SMF-28) using the tunable VCSEL under mechanical vibration below 10 KHz and 10-G acceleration shows little bit-error-rate degradation.

Long wavelength MEMS tunable VCSEL with InP-InAlGaAs bottom DBR

In this letter, we present the first demonstration of a long wavelength-tunable vertical-cavity surface-emitting laser (VCSEL) using an InP-InAlGaAs distributed Bragg reflector (DBR). The use of such a DBR improves the thermal resistance of the VCSEL while keeping the growth process simple. The devices show operation to temperatures greater than 75/spl deg/C, and single-mode devices emit powers as high as 0.9 mW at room temperature. The tuning range is as high as 17 nm.

Modulation of a vertical-cavity surface-emitting laser using an intracavity quantum-well absorber

We demonstrate a novel modulation technique with a vertical cavity surface-emitting laser (VCSEL) using an intracavity embedded voltage-biased quantum well absorber. We achieved a -3-dB small-signal bandwidth of 9 GHz and a response of 7 GHz//spl radic/(mA) by modulation of the absorber. Our calculations show that this technique introduces significantly less chirp at higher frequencies than direct current modulation.

High performance and novel effects of micromechanical tunable vertical-cavity lasers

Widely continuously tunable sources are key elements for many applications. This paper discusses the first integrated laser able to continuously tune its wavelength more than 1%: the micromechanical tunable vertical-cavity surface-emitting laser (VCSEL). These devices have demonstrated up 19.1 nm of continuous tuning, threshold currents as low as 460 /spl mu/A, and powers as high as 0.9 mW. In addition to these results, this paper discusses the tuning speed, lifetime, and applicability as a new broad-band source of these devices. Despite mechanical tuning, speeds of /spl mu/s are possible and long lifetime is expected. A detailed consideration of the design and fabrication of these devices is performed. Finally, an interesting mode switching effect is presented.

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. >

Sub-mA threshold 1.5-μm VCSELs with epitaxial and dielectric DBR mirrors

In this letter, we report low threshold 1.5-/spl mu/m vertical-cavity surface-emitting lasers with epitaxial and dielectric distributed Bragg reflector (DBRs). The device consists of a lattice-matched InAlAs-InAlGaAs DBR grown on an InP substrate, an InAlGaAs quantum well active region, a metamorphic GaAs tunnel junction, and a SiO/sub 2/-TiO/sub 2/ dielectric DBR. The current confinement is achieved by oxidizing an AlAs metamorphic layer grown on top of the active region. Small aperture devices show a minimum threshold of 0.8 mA at room temperature in continuous-wave operation.

Vertical-cavity lasers with an intracavity resonant detector

We demonstrate the first intracavity quantum-well photodetector within an InGaAs DBR QW VCSEL for top- and bottom-emitting structures. Minimal spontaneous emission is detected by the internal detector. Dark current is on the order of picoamperes, limited by our instrument noise floor. The internal detector demonstrates high insensitivity to external ambient light as compared to an external detector. Combining various measurement techniques, we gain an understanding of such an integration and discuss the various ramifications of the issues surrounding the design, fabrication, and performance of these integrated VCSEL-detectors. This configuration facilitates flexible tailoring of the laser efficiency and the integrated detector responsivity.

A long-wavelength MEMS tunable VCSEL incorporating a tunnel junction

In this letter, we describe the performance of a microelectromechanical system tunable vertical-cavity surface-emitting laser operating at 1550 nm and incorporating a tunnel junction for improved current injection and reduced optical loss. These lasers exhibit single-mode powers greater than 0.28 mW over 10 nm of tuning. Peak single-mode powers are greater than 0.8 mW and minimum threshold currents are less than 1 mA.

High-yield processing and single-mode operation of passive antiguide region vertical-cavity lasers

We report the first continuous-wave (CW) operation single-mode, low-threshold, passive antiguide region (PAR) vertical-cavity surface-emitting laser (VCSEL) using organometallic chemical vapor deposition (OMCVD) for the regrowth of the PAR structure. With improved laser wafer design, fabrication process and regrowth design, a stable single fundamental mode at high currents has been achieved experimentally for laser aperture as large as 16 /spl mu/m diameter. Single-mode power of 1.7 mW is achieved with more than 20-dB high-order mode suppression. The lasers show a more than 99% yield with high uniformity. Isolation etch and wet-thermal oxidation are used to study and eliminate the finite-leakage current in the PAR VCSELs. Using multimode rate equations in conjunction with beam propagation method, single-mode lasing criteria is derived for PAR VCSEL. PAR VCSEL is shown to be a very efficient structure to meet the single-mode lasing condition.

Transmission performance of a 1.5-μm 2.5-Gb/s directly modulated tunable VCSEL

We present experimental and theoretical transmission performance results for a novel 1.5-/spl mu/m 2.5-Gb/s directly modulated wavelength tunable vertical-cavity surface-emitting laser over different fiber types. Uncompensated reach of 100-800 km is demonstrated depending on the fiber choice.