The future evolution of photonics, for a wide spectrum of applications ranging from
established optical telecommunications to emerging opportunities such as biotechnology,
reprographics and projection displays, will depend on availability of compact, rugged,
efficient and inexpensive lasers which deliver high power, good beam quality, excellent
wavelength stability, low noise and long lifetime in the near infrared and visible regions.
This combination is not readily available from either of the traditional classes of
semiconductor laser, edge-emitters and vertical cavity surface emitters (VCSELs). Here
we describe a novel class of laser based on geometry similar to VCSELs but controlled
by an extended coupled cavity. These devices are scalable to high powers while
maintaining fundamental spatial mode performance, a feature that is essential to efficient
coupling into a single mode optical fibre or waveguide, or long range propagation in free
space. They are also ideally suited to mode locking, gain-switching and intracavity
frequency conversion, among other applications.
New laser-based light sources are highly desired for projection displays because of the need for longer lifetime, lower etendue, and higher color gamut. High power, frequency doubled red, green and blue (RGB) surface emitting diode laser arrays have been developed for use in low cost projection microdisplay television, digital cinema and pocket projectors. Single green lasers for pico-projectors using MEMS scanners have also been demonstrated.
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.
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.
Large area surface emitting lasers with extended cavity control have produced power levels of several hundred mW cw in a high quality TEM00 beam1. These lasers are highly manufacturable at low cost and differ from edge-emitting semiconductor diode lasers in that they are not waveguide devices but can operate in a circular Gaussian beam similar to solid-sate lasers. The high quality beams generated by these lasers can efficiently convert their output into other wavelengths using nonlinear optical materials. In addition, these lasers can operate with high peak power levels without the catastrophic degradation associated with edge-emitting diode lasers. Arrays of such devices can scale power to high levels with operation in the infrared or visible and UV wavelength regions. These lasers can all be tested at the wafer level to provide "know good die" for very low-cost manufacturing. The price points for manufacture of these lasers can reach levels suitable for many large-scale consumer and commercial applications.
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.
The reliability of novel, electrically pumped, vertical cavity 980-nm InGaAs lasers is demonstrated through accelerated life testing (ALT). The ALT methodology is used to detect failure modes as well as to obtain failure statistics. The time-to-failure (TTF) distribution and acceleration model are determined from over 200 devices tested from multiple wafers and assembly lots to account for process variation. The failure mode observed was gradual power degradation, while all other laser diode characteristics, e.g., threshold current, operating current and wavelength, remained stable. Laser output power degraded linearly in t1/2, where t is the stress time. The acceleration model best fitting the data is Black's equation with thermal activation energy of 0.89 eV and current density coefficient of 2.9. Verification of the acceleration model was confirmed through life testing over 500 devices at field operating conditions. The high level of reliability demonstrated meets strict telecommunications requirements.
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.
We describe the properties of novel blue-green sources based on intracavity frequency doubling of the Novalux family of high-brightness infrared surface-emitting lasers. They are highly compact, efficient, reliable, stable and manufacturable, capable of emitting over 40-mW cw power at 488 nm and other custom wavelengths in the range 460-532 nm with single frequency and single-spatial mode.
We describe the design, fabrication and performance of novel, electrically pumped, vertical compound cavity 976nm InGaAs lasers that emit at 488nm via intracavity second harmonic generation. The resulting light source is an ideal replacement for Ar-ion lasers used in a wide variety of bio-analytical instruments. We present characterization data for the laser to demonstrate its capabilities. Lastly, future directions for the technology are discussed, including a monolithic form and devices operating at 460 and 532nm.
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.
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.
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 (~10 mW) devices all the way to high power extended cavity lasers. The latter have demonstrated ~1 W 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 (0.05% rms from dc-2 MHz), sub 10 mrad beam pointing stability combined with small size, low power consumption (<10 W) and high efficiency.
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.
We describe design, fabrication and performance of novel, electrically pumped, vertical compound cavity InGaAs lasers emitting at 980 and 920 nm. The concept is scalable and has been demonstrated using monolithic low power (~10 mW) devices all the way to high power extended cavity devices which have demonstrated 1 W 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. We also describe uncooled vertical compound cavity lasers in TO-56 can packages which produce 50-100 mW of fiber coupled power. Finally, recent developments in intracavity frequency doubling are summarized.
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