William J. Kozlovsky

Generation of 41 mW of blue radiation by frequency doubling of a GaAlAs diode laser

A monolithic ring resonator of KNbO3 was used for efficient frequency doubling of a 856 nm GaAlAs diode laser. A special electronic servo technique was devised to lock the diode laser frequency to the KNbO3 cavity so that stable generation of blue output was obtained. With 105 mW of incident near‐infrared power, 41 mW of 428 nm radiation were produced. The conversion efficiency from electrical input power into the diode laser to blue output was ∼10%.

Very high-power (425 mW) AlGaAs SQW-GRINSCH ridge laser with frequency-doubled output (41 mW at 428 nm)

A very high-power AlGaAs single-quantum-well graded-index separate confinement heterostructure (GRINSCH) ridge laser operating in a diffraction-limited fundamental transverse mode up to 360 mW at a wavelength of 856 nm is presented. The maximum power output of the laser reached 425 mW, limited by thermal saturation of the device and not by catastrophic optical mirror damage. These lasers exhibit very high power levels and show excellent reliability at high output power levels. The extremely high, continuous-wave (CW) fundamental mode power combined with very low-intensity and optical phase distortion as well as low astigmatism render this ridge waveguide laser suitable for optical storage systems, printers, and direct frequency doubling. These devices have been successfully used for direct-frequency doubling of their output in a resonant KNbO/sub 3/ cavity yielding 41 mW of blue radiation at 428 nm. >

Blue light generation by resonator‐enhanced frequency doubling of an extended‐cavity diode laser

Frequency doubling of diode laser radiation was achieved by operating an AR‐coated diode laser in an extended laser cavity which contained a monolithic potassium niobate frequency doubling resonator as an intracavity element. Extended cavity operation ensured that the diode laser would oscillate only at frequencies that were resonant with the intracavity resonator. A diffraction grating was used to ensure single mode oscillation at the wavelength needed for noncritically phase‐matched second harmonic generation. At 100 mA of injection current to the GaAlAs diode laser, 14 mW of 429 nm light were produced.

Generation of 425‐nm light by waveguide frequency doubling of a GaAlAs laser diode in an extended‐cavity configuration

A blue output power of 1.2 mW at 425 nm was generated using a periodically poled KTP waveguide for frequency doubling of a grating tuned, extended‐cavity laser containing an antireflection‐coated GaAlAs SQW‐GRINSCH laser diode as the gain element. A normalized conversion efficiency of 127%/W cm2 was achieved in the extended‐cavity configuration.

Second‐harmonic generation in bulk and waveguided LiTaO3 with domain inversion induced by electron beam scanning

Bulk quasi‐phase‐matched frequency doubling experiments are reported for a lithium tantalate crystal which was periodically poled through its 0.5 mm thickness by electron beam scanning. The measured phase‐matching bandwidth of 1 nm for the 2‐mm‐long domain inverted section was close to the theoretical value of 0.4 nm, although the conversion efficiency was lower than theoretically expected. Chemical etching revealed domain duty‐cycle variations and incomplete inversions which are likely to have caused the lower conversion efficiency. Frequency doubling in waveguides fabricated in this material produced a normalized conversion efficiency of 290%/W cm2 and a phase matching bandwidth of 0.3 nm for a 1‐mm‐long domain inverted region.

Efficient diode-laser-pumped 946 nm Nd:YAG laser with resonator-enhanced pump absorption

The pump absorption of a 946-nm Nd:YAG laser was improved by resonating the GaAlAs diode-laser pump light in the 0.33-mm-long, monolithic laser resonator, whose maximum single pass pump absorption was only 18%. When the diode laser frequency was tuned to the pump resonance that was properly impedance matched, the Nd:YAG laser produced 29 mW from an incident diode laser power of 61 mW, for an overall efficiency of 48%. Laser oscillation was observed at both 946 nm and 938 nm. >

Optical recording in the blue using a frequency-doubled diode laser

We have developed a 428 nm blue laser source based on resonator-enhanced frequency doubling of a GaAlAs diode laser and have used this source to demonstrate writing and reading on an MO disk. The power, beam quality, and noise of the blue laser are sufficient for high-density optical recording.

Laser processing to adjust the suspension preload of magnetic recording head stack assemblies

The suspension preload of head stack assemblies (HSA) of hard disk drives is adjusted after assembly, using a laser processing technique. Side firing optical fibers are used to direct the laser radiation to the suspension hinge area in the HSA. The preload can be either increased or decreased depending on the pulse length, peak power and average power of the laser used. This allows one to adjust the mean and tighten the preload distribution. The processing technique is shown to only alter the preload and not affect the other functional properties of the suspension.

Laser gram load adjust for improved disk drive performance

A new manufacturing technology for enabling tight distribution of magnetic recording slider flying heights and lower slider disk spacings is described. The technique uses high intensity laser radiation to increase or decrease the suspension preload on the slider to change the flying height. The technique can be employed for tightening gram load or flying height distributions, contact avoidance or to adjust the magnetic recording capabilities of the disk drive.

Compact Blue Lasers For Optical Recording Applications

Compact blue laser sources with output powers of 10 and 40 mW at 473 and 428 nm have been developed using nonlinear frequency upconversion of GaAlAs diode lasers. These devices are attractive for application to high-density optical data storage.