Aram Mooradian

Efficient frequency doubling of a vertical-extended-cavity surface-emitting laser diode by use of a periodically poled KTP crystal

Blue light with a cw power in excess of 42 mW is generated from a frequency-doubled, extended-cavity InGaAs/GaAs 980-nm surface-emitting laser by use of a periodically poled KTP crystal.

Visible laser and laser array sources for projection displays

Laser-based projection displays have long attracted interest because of the multiple advantages (expanded color gamut, high resolution, longer lifetime, etc.) expected from lasers as compared to lamps. However, most of these advantages have been largely negated by the significant cost, size, and cooling requirements associated with lasers, and their inability to produce red, green, and blue colors in the same platform. In this paper, we review a new, laser array technology based of frequency-doubled, semiconductor, surface-emitting lasers. The key features of this technology, such as demonstrated multi-Watt output for rear-projection TVs, power levels scalable with the number of emitters, speckle suppression due to multi-emitter array, and a low-cost and compact design are discussed in detail.

532-nm laser sources based on intracavity frequency doubling of extended-cavity surface-emitting diode lasers

We introduce a novel type of cw green laser source, the Protera 532, based on the intracavity frequency doubling of an extended-cavity, surface-emitting diode laser. The distinguishing characteristics of this platform are high compactness and efficiency in a stable, single-longitudinal mode with beam quality M2 < 1.2. The laser design is based on the previously reported NECSEL architecture used for 488nm lasers, and includes several novel features to accommodate different types of nonlinear optical materials. The infrared laser die wavelength is increased from 976nm to 1064nm without compromising performance or reliability. The intracavity frequency doubling to 532nm has been demonstrated with both bulk and periodically poled nonlinear materials, with single-ended cw power outputs of greater than 30 mW.

High-power high-brightness 980-nm lasers based on the extended cavity surface emitting lasers concept

We describe design and performance of novel, electrically pumped, vertical compound cavity semiconductor lasers emitting at 980 nm. The laser combines a vertical cavity semiconductor laser with a partially reflecting output coupler and an external cavity for mode control. The concept is scalable and has been demonstrated in monolithic low power (few miliwatts) devices all the way to high power extended cavity devices which generate over 950 mW CW multimode power and 0.5 W CW power in a TEM00 mode, the latter with 90% coupling efficiency into a single mode telecommunication fiber. The concept has been applied to the development of uncooled lasers, mounted in TO-56 cans, capable of producing 50 to 100 mW of fiber-coupled power. We have also demonstrated the extended cavity lasers at wavelengths of 920 nm and 1064 nm. We present reliability data for the chips used in the extended cavity lasers.

Operation of a passively mode-locked extended-cavity surface-emitting diode laser in multi-GHz regime

We report on passive mode-locking of vertical cavity surface-emitting diode lasers at 980-nm wavelength, applied to different extended resonator configurations. Stable mode-locking producing pulses of approximately 50 ps in duration at up to 6-GHz repetition rate has been achieved. The use of external feedback results in pronounced harmonic pulse generation, extending the operational range of these new devices.

Laser sources at 460 nm based on intracavity doubling of extended-cavity surface-emitting lasers

Laser sources emitting at 460nm have been developed through intracavity doubling of an extended cavity, surface emitting semiconductor laser. These lasers are compact, spectrally pure, efficient, and have a high quality beam. The basic design is similar to previously reported work[1] at 488nm using Novalux Extended Cavity Surface Emitting Laser (NECSEL) structures. The choice of nonlinear material was found to be critical, with periodically poled materials providing distinct benefits over bulk materials. Output powers exceeded 20mW. The reliability of the completed lasers was found to be excellent.

Development of compact blue-green lasers for projection display based on Novalux extended-cavity surface-emitting laser technology

Compact and efficient blue-green lasers have been receiving increasing interest in the last few years due to their applications in various industries: bio-instrumentation, reprographics, microscopy, etc. We report on the latest developments in frequency-doubled, compact blue-green lasers, based on Novalux extended-cavity surface emitting laser (NECSEL) technology. This discussion will touch upon using NECSEL technology to go beyond a 5-20 milliwatt cw laser design for instrumentation applications and obtain a compact design that is scalable to higher power levels in an array-based architecture. Such a blue-green laser array platform can address the needs of laser light sources in the projection display consumer electronics markets, particularly in rear-projection televisions.

Novel 980-nm and 490-nm light sources using vertical cavity lasers with extended coupled cavities

We have developed novel electrically pumped, surface-emitting lasers emitting at 980 nm with an extended coupled cavity. The concept is scalable from monolithic low power devices all the way to high power extended cavity lasers. The latter have demonstrated 1W cw multi-mode and 0.5 W cw in a TEM00 mode and a single frequency, with 90% coupling efficiency into a single-mode fiber. By inserting a nonlinear optical medium in the external cavity, efficient and compact frequency doubling has been achieved with CW output powers 5-40 mW demonstrated at 490 nm. The latter devices are especially noteworthy due to their very low noise, sub 10 μrad beam pointing stability combined with small size, low power consumption and high efficiency.

490-nm coherent emission by intracavity frequency doubling of extended cavity surface-emitting diode lasers

We describe a novel blue-green laser platform, based on the intracavity frequency doubling of Novalux Extended Cavity Surface Emitting Lasers. We have demonstrated 5 to 40mW of single-ended, 488nm, single-longitudinal mode emission with beam quality M2<1.2. The optical quality of these lasers matches that of gas lasers; their compactness and efficiency exceed ion, DPSS, and OPSL platforms. These unique properties are designed to serve diverse instrumentation markets such as bio-medical, semiconductor inspection, reprographics, imaging, etc., and to enable new applications. We also present data on the reliability of this novel laser platform and its extensions to different wavelengths (in particular, 460nm and 532nm) and to next-generation, highly compact, monolithic intracavity-doubled lasers.

Invited Paper: Surface-emitting-diode lasers and laser arrays for displays

— High-power red, green, and blue laser light sources made from vertically emitting arrays of intracavity doubled IR lasers is reported. The emitted infrared light from a monolithic array of large-aperture vertical cavity lasers is converted into visible light using a PPLN doubling crystal in an external cavity. A volume Bragg grating provides simultaneous feedback for all emitters in the array and sets the laser wavelength. Increased diffraction losses for higher-order modes result in quasi-Gaussian beams with excellent conversion efficiency. Green 532-nm lasers with more than 5.8-W visible power have been demonstrated at a base temperature of 40°C. Blue 465-nm lasers with 4.4-W power at 40°C are unmatched in performance and wavelength when compared to competing GaN-based edge emitters. Typical wall-plug efficiencies are higher than 8%. We have measured single-emitter operating lifetimes to be more than 28,000 hours. Red lasers based on highly strained InGaAs achieve record laser powers of 2.0W at 618 nm in the same form factor as the green and blue lasers. Red single-emitter lifetimes of more than 10,000 hours have been attained. The technology described in this paper delivers on a full suite of cost efficient and reliable red, green, and blue lasers that meet the demands of the display markets.