The huge potential of tunable optical parametric oscillators (OPOs) derives from their exceptional wavelength versatility, as they are in principle not limited by the wavelength coverage dictated by the energy levels and transitions in a laser gain medium. However, while the OPO concept has been experimentally demonstrated already more than half a century ago, the progress in development of practicable and reliable turn-key devices that operate in continuous-wave (cw) mode has been stalled by several technical obstacles. This applies particularly for systems that sought to deliver tunable output across the visible spectral range (VIS), where only relatively recent advances have spurred the development of operationally stable benchtop devices. We discuss the principles and design challenges of such technically practicable cw OPOs, focusing on singly resonant OPO cavity designs that are linked with frequency conversion of the primary OPO output into different ranges of the visible spectrum. In this context, suitable choices and combinations of (quasi-phase-matched) nonlinear crystals are examined. We further discuss the overall performance highlights as well as current limitations of state-of-the art tunable cw OPO designs, and present first measurement results from conceptual approaches to shift and/or extend the wavelength coverage in future design layouts that eventually target commercialization. Last no least, after presenting real-world applications in an illustrative manner, we critically discuss how OPO technology, on the long run, can be expected to perform in the competition with alternatives based on common tunable laser designs.
There is recently an increasing interest in holographic techniques and holographic optical elements (HOEs) related to virtual reality and augmented reality applications which demand new laser technologies capable of delivering new wavelengths, higher output powers and in some cases improved control of these parameters. The choice of light sources for optical recording of holograms or production of HOEs for image displays is typically made between fixed RGB wavelengths from individual lasers (457 nm, 473 nm, 491 nm, 515 nm, 532 nm, 561 nm, 640 nm, 660 nm) or tunable laser systems covering broad wavelength ranges with a single source (450 nm – 650 nm, 510 nm – 750 nm) or a combination. Lasers for holographic applications need to have long coherence length (>10 m), excellent wavelength stability and accuracy as well as very good power stability. As new applications for holographic techniques and HOEs often require high volume manufacturing in industrial environments there is additionally a growing demand for laser sources with excellent long-term stability, reliability and long operational lifetimes. We discuss what performance specifications should be considered when looking at using high average power, single frequency (SF) or single longitudinal mode (SLM) lasers to produce holograms and HOEs, as well as describe some of the laser technologies that are capable of delivering these performance specifications.
In this work we present a compact, nanosecond pulsed, single frequency, single stage Yb-doped fiber amplifier by using an overall fiber core diameter of 20 μm. The key component is a custom made, compact, ultra-low noise, single frequency ring-cavity solid state laser (SSL) at 1064 nm used as a master oscillator. The SSL can be designed to provide nanosecond pulses with pulse energies in the sub-mJ range. Our ultimate goal is to develop a compact linearly polarized, single frequency, nanosecond pulsed laser source in an all-fiber format. Short (less than 1m), highly Yb-doped fibers have been used in order to suppress non-linear effects.
A compact, robust and efficient nanosecond pulsed optical parametric oscillator (OPO) generating radiation in the mid-
IR spectral range is reported. The OPO is based on periodically poled material for the efficient non-linear processes of
up-converting 1064 nm radiation to 1538 and 3450 nm respectively. Pulsed emission exceeding 130 mW average power
at the idler (3450 nm) with a total conversion efficiency of 30%, including both signal and idler, has been reached. The
maximum pulse energy of the idler is 11 μJ, pulse duration around 4 ns and peak power close to 3 kW. The results are
achieved for an optical pump power of 1.4 W at the entrance of the OPO and an electrical pump power of 14 W. The
total size of the OPO device is only 125x70x45 mm<sup>3</sup> (LxWxH) including the pump laser at 1064 nm. The idler output
radiation is narrowed by spectral filtering to < 1.5nm and temperature tuneable over > 50 nm. The OPO has a robust
design and withstands shocks up to 60g at 8 ms and the storage temperature is -20 °C to + 60 °C.
The compact size and low power consumption make this OPO device suitable for many kinds of molecular spectroscopy
applications in the areas of environmental monitoring and pollution control as well as in combustion physics and process
control. Integration of the OPO source into compact equipment for Photo Acoustic Spectroscopy (PAS) allowing fast
and highly sensitive detection of methane and ethanol at ppb-levels is also described.
A compact and efficient continuous wave, single mode, diode-pumped solid state laser is reported. The laser is based on
cascaded 2:nd order non-linear processes for intra-cavity frequency tripling to 355 nm wavelength using periodically
poled materials. CW emission exceeding 30 mW has been reached. The total size of the laser head is 125x70x45 mm<sup>3</sup>
(LxWxH), the ring cavity itself takes an area of only 30x20 mm<sup>2</sup> (LxW).
We report on the use of a compact Er-Yb:glass laser Q-switched by an AOM for seeding two-stage optical parametric amplifier realized in a single PPKTP crystal. We have generated 5 ns long pusles with a pulse energy exceeding 0.5 mJ. The parametric signal generation efficiency in the second amplification stage was 27%, while the pump depletion reached 39%. The two-stage OPA peak power gain was 30.1 dB for the seeding peak powers of 100W, while the gain reached 81 dB for the lowest seed peak powers of 0.7 mW. The OPA generated a diffraction-limited signal beam while maintaining the original spectral width of the seen.