Papers by Keyword: VCSEL

Abstract: Slant-face fiber side coupling of vertical cavity surface emitting laser (VCSEL) is reported. The direct coupling efficiency can reach 70%. The relative coupling efficiency variety caused by the position displacement and angle displacement was studied respectively. It is found that the cylinder of the fiber can collimate the divergent laser beam and improve aligning tolerance.

Abstract: A monolithically integrated 10Gbps Vertical Cavity Surface Emitting Laser (VCSEL) current driver is implemented in SMIC 0.18μm RF CMOS technology. High current driving capability as well as agile switching speed is achieved by shunt peaking technique and cascade structure. Test result shows that the driver can drive the common anode VCSEL well working at 10Gbps, and delivers 9.7mA modulation current. With single 1.8V power supply, the core power consumption is 22.5mW and the die size is 800μm×500μm.

Abstract: Oxygen plays a fundamental role in nature and industrial process, the fast on-line oxygen concentration detection is of great significance. Tunable diode laser absorption spectroscopy (TDLAS) is capable high selective, high sensitive, non-intrusive, this technique exploits the diode laser tunable and narrow bandwidth characteristics, by selecting one absorption line of the target gas to avoid interference from other gas and realize oxygen concentration fast on-line detection. In this paper, we use vertical cavity surface-emitting laser (VCSEL) as the light source, adopting the wavelength modulation spectroscopy and the harmonic detection technology to measure the second harmonic signal and realize oxygen concentration fast on-line detection. The detection concentration range between 0.1% to 40% and detection accuracy is 0.1%.

Abstract: A design of 10 Gbps Vertical Cavity Surface Emitting Laser (VCSEL) driver using 0.18µm CMOS technology is presented in this paper. The core unit of the driver consists of pre-amplify stage and output stage circuit. Technique of three stages differential amplifier with low impedance load and active feedback are employed in pre-amplify stage, and technique of C3A is adopted in output stage to get low power consume and high speed. The simulation results show that the circuit can work at the speed rate of 10 Gbps and maximum of 13 Gbps with a 1.8V power supply. The output modulation current is up to 12.5mA and the power dissipation is 77mW. The chip size is 0.45mm  0.47mm.

Abstract: Influence of using two oxide layers in the both sides of active layer with different position and aperture size on Vertical Cavity Surface Emitting Laser (VCSEL) performance is analyzed showing effects on the output power, single mode operation and threshold current. In addition, for improving speed we use ion implant area along with thick oxide layer to minimize parasitic elements. As the result, the proposed design exhibits much better stability of the fundamental mode over a wider current range, much higher output power, lower threshold current, than the conventional one with a high frequency response.

Abstract: In this paper we discussed the relation between depth errors that happened in films growth and incidence angle variation on DBR reflectivity. We assume that there is 10% depth error in high and low index materials, and there are four plus one situations to be considered. Four are combinations of Hi +/- 10% error and Lo +/- 10% error, and no error. Our simulation results show that the depth error makes the reflective band shift and it almost doesn’t reduce reflectivity. The thickness error of +/- 10% in (Al0.4Ga0.6N/GaN) DBR structure (15 pairs) at 420nm was 42nm. A theoretical analysis using Transfer Matrix Mode with MATLAB software on the influence of layer thickness and incidence angle variation in vertical-cavity surface-emitting lasers with distributed Bragg reflectors (DBRs) on lasing wavelength is presented. It is shown that changing the thickness of the layers in the DBR mirror by only 10% is sufficient to produce shifts in the peak reflectance wavelength up to ± 20 nm (for a blue laser at 420nm). This could limit the precision of a desired wavelength, which is its reproducibility.