Richard R. Craig

High-Efficiency Blue and True-Green-Emitting Laser Diodes Based on Non-c-Plane Oriented GaN Substrates

Using non-c-plane bulk GaN substrates, we demonstrate continuous-wave single-mode blue-emitting laser diodes operating with over 23% wall plug efficiency and over 750 mW output power, which represent the highest values reported to date. Furthermore, we demonstrate continuous-wave 520 nm green-emitting laser diodes with over 60 mW output power and 1.9% wall plug efficiency. The rapid performance evolution of laser diodes fabricated on non-c-plane orientations is validation of the benefits resulting from increased electron–hole overlap, reduced effective hole mass, and increased design flexibility.

High-power high-efficiency continuous-wave InGaN laser diodes in the violet, blue, and green wavelength regimes

We present new advances in green, blue, and violet InGaN-based laser diodes fabricated on nonpolar and semipolar GaN substrates. Using these novel crystal orientations, we report high power, high efficiency, continuous-wave operation from single-lateral-mode electrically pumped laser diodes at wavelengths from 405 nm to 500 nm. Additionally, we present continuous-wave lasing demonstrations out to 523 nm, representing the longest continuous-wave green laser emission reported to date. Wall-plug efficiencies of over 25% in the violet region, 16.2% in the blue region, and 2.2% in the 500 nm range are presented. These InGaN-based devices offer dramatic improvement in size, weight, and cost over conventional gas or solid state lasers and may enable a variety of new applications in defense, biomedical, industrial, and consumer projection displays.

High-performance blue and green laser diodes based on nonpolar/semipolar bulk GaN substrates

We present state-of-the-art performance from green and blue InGaN-based laser diodes fabricated on nonpolar/semipolar substrates. Using these novel crystal orientations, we demonstrate high-power, high-efficiency, and long-lifetime continuous-wave laser operation. For green wavelengths at 520 nm, we report on continuous wave single mode lasing with over 65 mW of output power and wall plug efficiencies over 2%. In the blue regime we describe single-mode lasers operating with over 23% wall-plug-efficiency and with output powers greater than 750 mW. To the best of the authors knowledge, this efficiency represents the highest reported to date for a single-mode blue laser. These InGaNbased devices offer dramatic improvement in performance, size, weight, and cost over conventional gas and solid state lasers for use in defense, biomedicine, and consumer projection displays.

Reliability and performance of InGaAs broad-area lasers emitting between 910 and 980 nm

High power InGaAs multi-mode broad area semiconductor lasers emitting between 190 nm and 980 nm are required as optical pumps for Er+ and Yb+ doped double clad fiber lasers and amplifiers. In this paper, we present performance and reliability of two generations of 100 micrometer aperture broad area devices emitting at 920 nm and 970 nm. The first generation devices have been deployed in the field with up to 2.5 W ex-facet optical power. More than 500,000 device-hrs of actual multi-cell lifetest data, and nearly 100 million accelerated device-hrs have been accumulated with 91FIT at 1.2W and 25 degrees Celsius or 1.9 million hrs MTBF at 2W and 25 degrees Celsius. A next-generation design further reduces thermal resistance, optical loss, and far-field divergence resulting in up to 4W ex-facet CW output power with superb reliability. Multi-mode fiber coupled modules demonstrate high coupling efficiency due to the reduced divergence angles of the new design. Lifetest of the new generation devices demonstrate the reliability of 167 FIT at 2W and 25 degrees Celsius or 499,000 hrs MTBF at 4W and 25 degrees Celsius.

State-of-the-art continuous-wave InGaN laser diodes in the violet, blue, and green wavelength regimes

We present state-of-the-art performance from green, blue, and violet InGaN-based laser diodes fabricated on nonpolar and semipolar GaN substrates. Using these novel crystal orientations, we demonstrate high power, high efficiency, continuous-wave operation from single-lateral-mode electrically pumped laser diodes at wavelengths from 405 nm to 500 nm. Additionally, we present the longest reported continuous-wave lasing demonstration of 525 nm and an output power of over 9 mW at 521 nm. Wall-plug efficiencies of over 25% in the violet region, 17.5% in the blue region, over 5% at 472nm, and 2.2% in the 500 nm range are reported. These InGaN-based devices offer dramatic improvement in size, weight, and cost over conventional gas and solid state lasers and may enable a variety of new applications in defense and security.

High power, high reliability laser diodes

Results are presented on catastrophic damage limits and life-test measurements for four types of high-power laser diodes operating at wavelengths between 980 nm and 690 nm. The laser diodes under consideration are CW multimode lasers, CW laser bars, quasi-CW bars/2D stacked arrays, and single transverse mode lasers.

Gigabyte/s parallel fiber-optic links based on edge emitting laser diode arrays

We present a ten-channel parallel fiber optic link consisting of a transmitter based on an edge emitting laser diode array operating nominally at 1 /spl mu/m wavelength and a complementary receiver based on an InGaAs pin photodetector array. We demonstrate fiber optic link performance up to data rates of 1 Gb/s per channel with low skew at measurement time limited bit error rates lower than 10/sup -11/ over 100 m of multimode fiber ribbon cable. The transmitter is operational, with very clear eye opening, up to baseplate temperatures of 105/spl deg/C.

High-power high-speed single-mode diode lasers for optical intersatellite link applications

High power single-mode AlGaAs semiconductor lasers operating between 820 nm and 860 nm (SDL-5400 series diodes) have been successfully qualified for deployment in many free-space inter-satellite communication link programs. Traditionally these high power devices did not have sufficient bandwidth for direct high speed modulation because of large device and package parasitics. We have improved the device parasitics of the SDL-5430 laser diode, i.e. reduced the RC product, from 240 ps to about 40 ps. The initial measurements indicate that this device (SDL-5480) is suitable for high power optical inter-satellite link (OISL) applications at data rates greater than 1 Gbit/s. The preliminary life test indicates that the new device has better a reliability than the previous design.

Highly reliable high-power cw AlGaAs (808 nm) 1-cm bar laser diodes for Nd:YAG pump application

The reliability of high power continuous-wave (CW) 1 cm monolithic AlGaAs (808 nm) laser diodes is extensively investigated. Lasers with two total aperture sizes, 1800 micrometers and 3000 micrometers , are life tested at power levels of 10 W and 20 W, respectively for 1500 hours to 4000 hours at 30 degree(s)C heatsink temperature. These lasers exhibit no failures during the lifetests (total device hours of 45,000 hours for the 10 W lasers and 42,000 hours for the 20 W lasers). We demonstrate a mean time between failures (MTBF) exceeding 50,000 hours and a median life (ML) of 40,000 hours for the 10 W laser diode and a MTBF over 48,000 hours and a ML of 13,000 hours for the 20 W laser diode.

Reliability of high-power semiconductor laser arrays

The reliability of continuously operating (cw) high power laser arrays is a critical factor for the acceptance of these devices in a wide range of applications. Extensive investigation into the reliability of semiconductor lasers has led to an improved understanding of failure mechanisms such as material defects, mirror damage and solder related failures as well as to methods which significantly suppress the occurrence of catastrophic failure. Furthermore, as a result of material quality improvements, laser arrays exhibit very low gradual degradation for high power operation up to 2 Watts cw. Long term lifetest data shows that the projected medium life at room temperature of such devices exceed 100,000 hours at 2 W cw.