A.I. Ferguson

0.5-W single transverse-mode operation of an 850-nm diode-pumped surface-emitting semiconductor laser

We report the power scaling of a diode-pumped GaAs-based 850-nm vertical external-cavity surface-emitting laser, by use of an intracavity silicon carbide (SiC) heatspreader optically contacted to the semiconductor surface. To our knowledge, this is the first demonstration of bonding of SiC to a III-V semiconductor structure using the technique of liquid capillarity. High output power of >0.5 W in a circularly symmetric, TEM/sub 00/ output beam has been achieved with a spectral shift of only 0.6 nm/W of pump power. No thermal rollover was evident up to the highest pump power available, implying significant further output-power scaling potential using this approach.

Actively stabilized single-frequency vertical-external-cavity AlGaAs laser

We report on actively stabilized single-frequency operation of a vertical-external-cavity surface-emitting semiconductor laser (VECSEL). The VECSEL was locked to a 300-MHz reference cavity allowing a relative frequency measurement that indicated a laser linewidth of 3 kHz. Coarse tuning over an 8.5-nm range was achieved, with fine tuning over 250 MHz. The laser produced up to 42 mW of output power in single-frequency operation.

Narrow linewidth operation of a tunable optically pumped semiconductor laser

We report on the single-frequency operation of an optically pumped external cavity semiconductor laser. An output power of up to 400 mW is obtained in a single spatial and longitudinal mode and with a tuning range exceeding 10 nm. The laser has been stabilized electronically to a reference cavity with a relative linewidth of less than 5 kHz.

Optical in-well pumping of a vertical-external-cavity surface-emitting laser

A scheme is demonstrated for optical pumping of a vertical-external-cavity surface-emitting laser. The scheme is based on absorption of the pump light within the wells of the multiple-quantum-well gain structure rather than the conventional approach of absorption of a shorter wavelength in the barrier regions. The operation of a laser around 850 nm pumped by an 808 nm source demonstrates the potential of this technique for allowing operation at a significantly shorter range of wavelengths for these devices in general and specific application of high-brightness pump lasers for devices in this spectral region. A further advantage is the smaller quantum defect which results in reduced heating of the gain medium. These advantages are achieved while maintaining a slope efficiency of up to 18%, which is comparable to results obtained with a traditional pumping scheme with a similar gain medium.

Confocal microscopy using an InGaN violet laser diode at 406nm.

We report on the application of a novel all-solid-state violet laser diode source to confocal microscopy. The source has the potential to replace argon ion lasers in a range of fluorescence based imaging systems. Improvements in system performance and image quality through the use of anamorphic prisms to modify the beam profile have been characterised. These modifications have permitted high quality, optically sectioned images to be obtained from laser diodes operating around 406nm. Living mammalian cells stained with a range of biologically significant fluorophores have been imaged. In addition, it has been shown that at this wavelength it is possible to image dyes that normally require excitation with UV argon laser lines.

Diode-pumped passively mode-locked Nd:KGd(WO4)2 laser with 1-W average output power

Continuous-wave passive mode locking of a diode-pumped Nd:KGd(WO(4))(2) laser is demonstrated. The use of a saturable Bragg reflector as the mode-locking element permits the generation of 6.3-ps pulses, assuming a sech(2) pulse shape. An output power of 1 W was obtained, which corresponds to a slope efficiency of 34.5%.

Efficient Raman shifting of high-energy picosecond pulses into the eye-safe 1.5-µm spectral region by use of a KGd(WO4)_2 crystal

We report an efficient transient stimulated Raman conversion of high-energy picosecond pulses at 1350 nm into the eye-safe 1500-nm wavelength range by use of a KGd(WO4)2 crystal. The conversion efficiency into either 1503- or 1537-nm radiation (767- or 901-cm(-1) Raman modes, respectively) is measured to be approximately 10% in a single-pass configuration. The transient Raman gain coefficient is found to be approximately 0.8 cm/GW. Simultaneous generation of multiple Raman lines is also observed.

Doubly resonant optical parametric oscillator synchronously pumped by a frequency‐doubled, mode‐locked, and Q‐switched diode laser pumped neodymium yttrium lithium fluoride laser

We report on the synchronous pumping of an optical parametric oscillator (OPO) using a frequency‐doubled, mode‐locked, and Q‐switched diode laser pumped yttrium lithium fluoride laser. Using a 1 W pump diode, frequency modulation mode locking, and acousto‐optic Q switching, a pulse envelope of 75 ns duration and 45 μJ of energy in 21 ps pulses at 360 MHz repetition rate was obtained. This was frequency doubled in 90° phase‐matched MgO:LiNbO3 with 47% energy conversion efficiency. The doubly resonant OPO based upon temperature‐tuned MgO:LiNbO3 had an energy conversion efficiency of 20% at degeneracy. The tuning range of 983–1119 nm was limited by the mirror reflectivities.

Operation of an optical in-well-pumped vertical-external-cavity surface-emitting laser

We report the operation of an optical in-well-pumped vertical-external-cavity surface-emitting laser. The laser delivers 1 W at 855 nm and is pumped with a cost-effective fiber-coupled laser diode emitting at 806 nm. The laser modal gain is examined and ways of optimizing the system are investigated and discussed.

Saturable Bragg reflector-based continuous-wave mode locking of Yb:KGd(WO4)2 laser

We demonstrate the saturable Bragg reflector (SBR)-based stable self-starting continuous-wave mode locking of a Yb:KGd(WO4)2 laser. With a double quantum well SBR structure the shortest pulses observed had durations of 169 fs, average powers of 18 mW and an oscillating wavelength centred on 1028 nm.