G.S. Li

Top-emitting micromechanical VCSEL with a 31.6-nm tuning range

We report a top-emitting micromechanical vertical-cavity surface-emitting laser (VCSEL) with a continuously tunable wavelength range of 31.6 nm, the widest tuning range demonstrated by a VCSEL to date. Good laser characteristics are maintained throughout the tuning range centered at 935 nm: continuous-wave (CW) threshold occurs between 1.24.5 mA while output power at 10-mA DC bias remains between 0.5 and 1.6 mW. By analyzing the pulsed differential quantum efficiency as a function of emission wavelength, we conclude that tilt loss from the cantilever design does not significantly affect the tuning range or laser performance.

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.

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.

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>>

Accurate molecular beam epitaxial growth of vertical-cavity surface-emitting laser using diode laser reflectometry

Accurate and reproducible molecular beam epitaxial (MBE) growths of vertical-cavity surface-emitting lasers (VCSELs) and various vertical-cavity structures are achieved using an extremely simple, cost-effective and compact diode laser reflectometry pre-growth calibration system. Average growth accuracy of 0.25% with a 0.40% standard deviation is obtained over a period of 6 months for a variety of growth structures. Low threshold continuous wave room temperature operation is achieved from all the VCSEL wafers.<<ETX>>

Frequency tuning of self-pulsations in a VCSEL with a voltage-controlled saturable absorber

Summary form only given. Self-pulsating lasers are extremely useful in a variety of applications, including multimode fiber systems and optical disk readout. It is desirable to attain self-pulsating vertical-cavity surface-emitting lasers (VCSELs) because the surface-normal geometry facilitates two-dimensional array configurations and wafer-scale fabrication. We previously demonstrated on-off control of GHz-range self-pulsations in a VCSEL. In this work, we believe we demonstrate for the first time 700 MHz frequency tuning of self-pulsations in a VCSEL by using an active quantum well absorber integrated in the mirror stack. These pulsations have a 700 kHz relative frequency linewidth. We present theoretical and experimental demonstrations of a novel design criterion, whereby the absorber wavelength is slightly shorter than the lasing wavelength, leading to the negative differential resistance, which is essential to obtaining self-pulsation. By careful device design, the VCSEL can be made to self-pulsate at low absorber biases, GHz-range frequencies, and potentially at high output powers.

Self-pulsating VCSEL with controllable quantum-well saturable absorber

We experimentally demonstrate the first self-pulsating VCSEL with a controllable quantum-well saturable absorber. Self-pulsation frequencies as high as 2 GHz were obtained. Self-pulsating lasers have proven extremely useful in applications where elimination of optical feedback and high-speed driving circuitry is needed. In this work, we present the first demonstrated InGaAs DBR QW VCSEL with self-pulsations occurring through a voltage-controlled saturable absorber.

Novel intracavity modulator integrated with a vertical-cavity surface-emitting laser

nant frequency and equivalent damping frequency (y/27r). These quantities for a -4 X 4 pm2 laser with 0.5 mA threshold current are plotted in Fig. 2 along with the -3 dB bandwidth. At low bias currents, the bandwidth and resonant frequency increase in proportion to the square root of the current above threshold as expected from the conventional rate equation analysis. The rate of increase in this region yields a modulation current efficiency factor (MCEF) of 14.2 GHz/VmA, which is slightly lower than the highest value we previously reported for oxide-confined VCSELs with InGaAs quantum wells. The resonant frequency increases steadily to 15 GHz at 2.7 mA and then becomes nearly constant. The -3 dB bandwidth is as high as 21.5 GHz. Large signal, digital modulation experiments were also performed. Figure 3 shows the eye diagram during a 12 Gb/s test that uses -8 X 8 pmz multimode lasers with both levels above threshold. Bit error rates as low as were observed in preliminary investigations at this data rate. Reducing the 0 level slightly below threshold resulted in substantial, pattern dependent jitter. Jitter measurements will be presented. This work was supported by the United States Department of Energy under Contract DE-AC04-94ALS5000. I . K. L. Lear et al., Electron. Lett. 32(5), 457 (1996). 2. K. D. Choquette et al., Photon. Technol. Lett., 7( 1 l ) , 1237 (1995). CWA3 8:45 am

A very uniform single mode addressable oxide confined VCSEL array

Summary form only given. We report the first single mode independently addressable oxide confined GaAs-AlGaAs QW DBR VCSEL laser array. The 4/spl times/8 VCSEL array has very uniform electrical, modal and geometrical characteristics that make it ideal for 2D array applications.

Novel self-chirped VCSEL with a micromechanical resonator

We demonstrate a self-chirping VCSEL laser diode with a 10 nm bandwidth, sub-milliamp threshold, and 0.2 mW total power in a single mode. The self-chirping is achieved by integrating the VCSEL with a micromechanical resonator and biasing with a feedback load.