Lightwave Electronics Corporation

A Lightwave Electronics model 122 microprocessor controlled Nd:YAG laser, produced in about 1990. This laser was based on the nonplanar ring oscillator design. This continuous-wave, single-frequency laser was aimed at the laboratory market. Lightwave Electronic's biggest market was for OEM lasers, (lasers used as components in other manufacturer's systems), primarily Q-switched lasers for micromachining.

Lightwave Electronics Corporation was a developer and manufacturer of diode-pumped solid-state lasers, and was a significant contributor to the creation^[1] and maturation of this technology. Lightwave Electronics was a technology-focused company, with diverse markets,^[2] including science and micromachining. Inventors employed by Lightwave Electronics received 51 US patents,^[3] and Lightwave Electronics products were referenced by non-affiliated inventors in 91 US patents.^[4]

Lightwave Electronics was a California corporation which was founded in 1984. The primary founders were Robert L. Mortensen, a former executive at the laser manufacturer Spectra Physics; Dr. Robert L. Byer, a professor of Applied Physics at Stanford University; and the Newport Corporation, then headed by Dr. Milton Chang. Mortensen was president at the company’s founding, and he served as president for almost 15 years.^[5] Phillip Meredith was president from 2000 until the sale of the company in 2005.^[6] JDS Uniphase Corporation (JDSU, now Lumentum, stock ticker LITE) purchased Lightwave in 2005, for $65M.^[7][8] At that time, the company had 120 employees. The company was located in Mountain View, California.

Products

In the scientific community, Lightwave Electronics was best known for single-frequency lasers based on the nonplanar ring oscillator design.^[9] These lasers operated at the wavelengths of 1064 nm and 1319 nm, and were based on the laser material neodymium-doped yttrium-aluminum garnet (Nd:YAG). The first-generation Laser Interferometer Gravitational Wave Observatory (LIGO) was based on these lasers, operating at 1064 nm.^[10] Two Lightwave nonplanar oscillators were launched into space in 2004 as components of NASA’s Tropospheric Emission Spectrometer, an earth-observing satellite instrument which was still operational in 2015.^[11] Lightwave Electronics produced a visible (532 nm) laser source based on frequency doubling the output of a nonplanar ring oscillator.^[12] The nonlinear material used was magnesium-doped lithium niobate. Another member of the nonplanar ring product family was an “injection seeding” system which was used to enforce single-frequency oscillation in 1-joule-level lamp-pumped Q-switched lasers, improving the utility of those lasers for quantitative spectroscopy.^[13][14] This injection seeding system was the first Lightwave Electronics product with significant sales.

Lightwave Electronics' first significant success in industrial markets was a series of acousto-optically Q-switched lasers^[15][16] at 1047 nm, based on neodymium-doped yttrium lithium fluoride (Nd:YLF), and at 1342 nm, based on neodymium-doped yttrium orthovanadate, which were used to improve yield in semiconductor memory manufacturing. For about 2 decades, from about 1988 to 2008, semiconductor manufacturers used the Lightwave Electronics miniature Q-switched lasers in the link blowing step^[17] during the production of the majority of the world’s dynamic random-access memory chips. These miniature Q-switched lasers were in systems built by Electro Scientific Industries, GSI, and Nikon.

Also of significant industrial importance was a series of internally frequency converted Q-switched lasers, with 2 to 20 Watt of ultraviolet output at 355 nm,^[18] used for a variety of micromachining applications. Lightwave introduced these UV lasers in 1998. The nonlinear frequency converting material was lithium triborate (LBO). Lightwave’s Q-switched multi-watt UV lasers emitted longer pulses than competing lasers and allowed effective processing of materials,^[19] probably by melting as opposed to ablation (vaporization), thus lowering the power needed for removing material in operations such as laser-drilling small holes in circuit boards, or laser-cutting circuit boards^[20]

For a few years (circa 1996), Lightwave Electronics produced an acousto-optically mode-locked laser with low frequency jitter and drift. The most significant application was for high-speed measurements of voltages as a step in the design and improvement of integrated circuits.^[21] A distinct line of mode-locked lasers produced ultraviolet output at 355 nm, used for fluorescence excitation in flow cytometry applications.^[22] Mode-locking was passive, using a semiconductor saturable absorber. In the late 1990s Lightwave Electronics produced a Nd:YAG laser internally frequency doubled to 532 nm with potassium titanyl phosphate (KTP), used in ophthalmology.

Technology

Photograph shows the technique used to mount optics in a Lightwave Electronics single-frequency frequency-doubled laser. The optic in the left foreground is bonded with a thin layer of UV-curing adhesive to a support block, also made of glass, which is bonded to the platform. This design approach allows 5 degrees of freedom for the optic, with a thin adhesive bond.^[23]

Early products benefited from relationships with Stanford University and other Bay Area laboratories. The nonplanar ring oscillator technology was invented at Stanford University,^[24] and the patent^[25] was licensed to Lightwave Electronics. The injection seeding product was developed with cooperation from SRI International and Sandia National Laboratories (Livermore).^[13][14]

Lightwave Electronics is listed as the assignee on 51 United States patents.^[3] Several of these relate to active laser stabilization, including stabilization of optical frequency,^[26] of intensity,^[27] and of pulse repetition rate^[28] and pulse energy.^[29] Another set relate to laser manufacturing techniques. Early Lightwave Electronics lasers used solder to permanently mount optics in place.^[30] Later lasers, such the one shown in the figure, used adhesive cured by ultraviolet light.^[23][31]

Lightwave Electronics' nonplanar ring lasers, and the infrared Q-switched lasers used for DRAM production, were "end-pumped," meaning that the beam from the semiconductor laser pump was co-axial with the beam of the pumped laser. Later lasers, including all of the 355 nm lasers, were side-pumped. Small-diameter (<2 mm) Nd:YAG rods were pumped by powerful (>20 watt), large-aperture semiconductor lasers placed alongside the rods. Lightwave Electronics developed and patented a design enabling efficient side-pumping of a laser while maintaining diffraction-limited output.^[32] The end-pumped pumped products were limited in power to less than 1 watt, while side-pumped products have exceeded 20 watts.

Lightwave Electronics made extensive use of the Small Business Innovation Research (SBIR) Program, established in 1982.

Successor Companies

Spin-off companies from Lightwave Electronics Corporation include Electro-Optics Technology, of Traverse City MI; Time-Bandwidth Products of Zurich, Switzerland, now a part of Lumentum; and Mobius Photonics,^[33] acquired by IPG Photonics. Products sold by Lumentum in 2015 which derive from Lightwave Electronics Corporation products are: the NPRO 125/126 series nonplanar ring lasers, the Q-series Q-switched 355 nm lasers, and the Xcyte quasi-continuous 355 nm lasers.^[34]

References