Yabo Li

Quantum well intermixing

Embodiments of a method of quantum well intermixing (QWI) comprise providing a wafer (1) comprising upper and lower epitaxial layers (10, 13), which each include barrier layers, and a quantum well layer (11) disposed between the upper and lower epitaxial layers (10, 13), applying at least one sacrificial layer (21) over the upper epitaxial layer, and forming a QWI enhanced region and a QWI suppressed region by applying a QWI enhancing layer (31) over a portion of the sacrificial layer, wherein the portion under the QWI enhancing layer (31) is the QWI enhanced region, and the other portion is the QWI suppressed region. The method further comprises the steps of applying a QWI suppressing layer (41) over the QWI enhanced region and the QWI suppressed region, and annealing at a temperature sufficient to cause interdif fusion of atoms between the quantum well layer (11) and the barrier layers of the upper epitaxial layer and the lower epitaxial layer (10, 13).

107-mW low-noise green-light emission by frequency doubling of a reliable 1060-nm DFB semiconductor laser diode

We have generated 107-mW green-light emission by frequency doubling of a reliable 1060-nm distributed feedback (DFB) laser diode using a periodically poled MgO-doped lithium niobate waveguide in the most compact single-pass configuration. The green power variation is lower than 1% at frequencies below 82 kHz. The relative intensity noise of -150 dB/Hz has been measured at 100 MHz. We also report 5000-h life-test results of 1060-nm DFB lasers at 80/spl deg/C.

High-power high-Modulation-speed 1060-nm DBR lasers for Green-light emission

We report on the static and dynamic performance of high-power and high-modulation-speed 1060-nm distributed Bragg reflector (DBR) lasers for green-light emission by second-harmonic generation. Single-wavelength power of 387 mW at 1060-nm wavelength and green power as high as 99.5 mW were achieved. A thermally induced wavelength tuning of 2.4 nm and a carrier-induced wavelength tuning of -0.85 nm were obtained by injecting current into the DBR section. Measured rise-fall times of 0.2 ns for direct intensity modulation and 0.6 ns for wavelength modulation make the lasers suitable for >50-MHz green-light modulation applications

304 mW green light emission by frequency doubling of a high-power 1060-nm DBR semiconductor laser diode

We report for the first time, to the best of our knowledge, 304 mW green light emission generated by frequency doubling of the output from a 1060-nm DBR semiconductor laser using a periodically poled MgO-doped lithium niobate waveguide in a compact single-pass configuration. The excellent performance of these DBR lasers, including a kink-free power greater than 750 mW, single-spatial-mode output beam, single-wavelength emission spectra, and high wavelength-tuning efficiency, plays an important role in the generation of high-power green light.

High power 1060-nm raised-ridge strained single-quantum-well lasers

We report a high kink-free facet power of 852 mW and a high single-wavelength facet power of 350 mW for 1060-nm raised-ridge Fabry-Perot (FP) and distributed-feedback (DFB) lasers, respectively.

High-power distributed Bragg reflector lasers for green-light generation

We report on the design, fabrication and performance of high-power and high-modulation-speed 1060-nm DBR lasers for green-light emission by second harmonic generation. Single-spatial-mode and single-wavelength power more than 450 mW of 1060-nm wavelength was achieved with a 3-section DBR laser with non-absorbing DBR and phase sections created by an impurity-free quantum-well intermixing technique. A thermally-induced wavelength tuning of 2.4 nm and a carrier-induced wavelength tuning of -0.85 nm were obtained by injecting current into the DBR section. The green power as high as 104.6 mW was demonstrated by coupling the DBR laser output to a second-harmonic-generation waveguide. Measured rise/fall times of 0.2 ns for direct intensity modulation and 0.6 ns for wavelength modulation make the DBR lasers suitable for >=50-MHz green-light-modulation applications. The detrimental thermally-induced patterning effect and a differential-phase modulation scheme as a solution are discussed.

Testing of high-power semiconductor laser bars

A measurement system called laser bar prober for characterizing high-power semiconductor edge-emitting laser bars is described. The laser bar prober is fully automated to handle testing of large numbers of lasers, is multifunctional to measure various laser characteristics and is accurate in predicting performance of fully mounted lasers. The bar prober has been proven to be an effective instrument for screening lasers during manufacturing process as well as an indispensable tool for providing rapid feedback to the development of new laser structures. In this paper, the design of the laser bar prober is described and a few examples of its applications are given; in particular, a time-resolved technique to correlate the measurement data of a laser within a laser bar to those of a fully mounted laser is demonstrated.

Wavelength tunable high-power single-mode 1060-nm DBR lasers

The wavelength tunable 1060-nm distributed Bragg reflector (DBR) laser chip consists of three sections: a gain section for lasing, and phase and DBR sections for wavelength control. A micro-heater is lithographically integrated on the top of the DBR section to tune the emission wavelength. The phase section is designed with either a top heater or by current injection to provide fine tuning of the wavelength. The wavelength tuning efficiency of our DBR laser is approximately 9 nm/W at the laser heat sink temperature of 25°C. Single-mode output powers of 686 mW and 605 mW were obtained at a CW gain drive current of 1.25 A and heat sink temperatures of 25°C and 60°C, respectively. Gain-switching by applying 1.1 GHz sinusoidal signal mixed with 600 mA DC injection current produced approximately 58 ps long optical pulses with 3.1 W peak power and 228 mW average power. The average power increased to 267 mW and pulse width broadened to 70 ps with DC bias of 700 mA. In CW operation, one of the applications for high-power single-mode DBR lasers is for non-linear frequency conversion. The light emitted from the 1060-nm DBR laser chip was coupled into a single-mode periodically poled lithium niobate (PPLN) crystal waveguide. Up to 350 mW optical power at 530 nm with the wall-plug efficiency of up to 15% was demonstrated.

Reliability and qualification of high-power wavelength-tunable 1060-nm laser diode for ultra-compact laser projector application

We report highly reliable 1060-nm DBR semiconductor lasers after aging the gain section and DBR-section heater for up to 24000 and 11000 hrs, respectively, at various high-stress conditions.

480-mW DBR Laser Integrated with Micro Heaters for Wavelength Tuning

We fabricated 1060-nm DBR lasers with 480-mW output power and integrated micro heaters. A 20-nm discrete wavelength tuning using Bragg-section heater alone and a 1-nm continuous tuning using both Bragg- and phase-section heaters are demonstrated.