Daniele Carmine Parrotta

Multiwatt, Continuous-Wave, Tunable Diamond Raman Laser With Intracavity Frequency-Doubling to the Visible Region

Multiwatt emission from a continuous-wave diamond Raman laser pumped within a diode-pumped InGaAs-based semiconductor disk laser (SDL) is reported. The Raman laser achieved a maximum output power of 4.4 W at 1228 nm with a beam quality factor (M2) of 1.4 and diode-to-Stokes conversion efficiency of 14.2%. Via tuning of the SDL oscillation wavelength, the diamond Raman laser was tuned from 1209 to 1256 nm, with output power exceeding 4 W over a 10-nm range. The evolution of the emission spectra and beam quality of both the SDL and the Raman laser have been investigated for different pump powers, revealing the onset of spectral broadening and beam “clean-up” effects with increasing power. The SDL spectral linewidth and beam overlap are then taken into account in calculations of the efficiency of the Raman laser. Using intracavity frequency-doubling in lithium triborate (LBO) within the Raman laser, up to 1.5-W output power at orange wavelengths was achieved with M2 <; 1.3 and linewidth ~0.1 nm full-width at half-maximum. Tuning of the visible emission was achieved via tuning of the SDL and temperature control of the LBO and covered the range 604.5-619.5 nm.

Continuous-wave Raman laser pumped within a semiconductor disk laser cavity

A KGd(WO₄)₂ Raman laser was pumped within the cavity of a cw diode-pumped InGaAs semiconductor disk laser (SDL). The Raman laser threshold was reached for 5.6 W of absorbed diode pump power, and output power up to 0.8 W at 1143 nm, with optical conversion efficiency of 7.5% with respect to the absorbed diode pump power, was demonstrated. Tuning the SDL resulted in tuning of the Raman laser output between 1133 and 1157 nm.

Tunable continuous-wave diamond Raman laser

Continuous-wave operation of a diamond Raman laser, intracavity-pumped by a diode-pumped InGaAs semiconductor disk laser (SDL), is reported. The Raman laser, which utilized a 6.5-mm-long synthetic single-crystal diamond, reached threshold for 5.3 W of diode laser pump power absorbed by the SDL. Output power up to 1.3 W at the first Stokes wavelength of 1227 nm was demonstrated with excellent beam quality and optical conversion efficiency of 14.4% with respect to absorbed diode laser pump power. Broad tuning of the Raman laser output between 1217 and 1244 nm was achieved via intracavity tuning of the SDL oscillation wavelength.

Intracavity Raman conversion of a red semiconductor disk laser using diamond

We demonstrate a diamond Raman laser intracavity-pumped by a red semiconductor disk laser (~675 nm) for laser emission at around 740 nm. Output power up to 82 mW of the Stokes-shifted field was achieved, limited by the available pump power, with an output coupling of 1.5%. We also report wavelength tuning of the diamond Raman laser over 736 - 750 nm.

InGaAs-QW VECSEL emitting >1.300-nm via intracavity Raman conversion

We report intracavity Raman conversion of a long-wavelength InGaAs-QW VECSEL to ~1320 nm, the longest wavelength yet achieved by a VECSEL-pumped Raman laser. The setup consisted of a VECSEL capable of emitting >17W at 1180nm and tunable from 1141-1203nm and a 30-mm-long KGd(WO4)2 (KGW) Raman crystal in a coupled-cavity Raman resonator. The Raman cavity was separated from the VECSEL resonator by a tilted dichroic mirror, which steers the Raman beam to an output coupler external to the VECSEL. The spectral emission of the VECSEL, and consequently of the Raman laser, was set by a 4-mm-thick quartz birefringent filter in the VECSEL cavity. The KGW Raman laser was capable of emitting 2.5W at 1315 nm, with M2~2.7 and >4% diode-to-Stokes conversion efficiency. The Raman laser emission was tunable from 1295-1340 nm, limited by the free spectral range of the birefringent filter. Spectral broadening of the fundamental emission was observed during Raman conversion. At the maximum Raman laser output power, the total linewidth of the VECSEL spectrum was ~0:7nm FWHM. As a consequence, the Raman laser emission was also relatively broad (~0.9nm FWHM). Narrow (<0.2nm FWHM) Raman emission was obtained by inserting an additional 100 µm etalon within the VECSEL cavity. With this configuration the fundamental intracavity power clamped at its value at the Raman threshold, suggesting an enhanced effective Raman gain, but the maximum output power of the Raman laser was 1.8 W.

The UK National Quantum Technology Hub in Sensors and Metrology

The UK National Quantum Technology Hub in Sensors and Metrology is one of four flagship initiatives in the UK National of Quantum Technology Program. As part of a 20-year vision it translates laboratory demonstrations to deployable practical devices, with game-changing miniaturized components and prototypes that transform the state-of-the-art for quantum sensors and metrology. It brings together experts from the Universities of Birmingham, Glasgow, Nottingham, Southampton, Strathclyde and Sussex, NPL and currently links to over 15 leading international academic institutions and over 70 companies to build the supply chains and routes to market needed to bring 10–1000x improvements in sensing applications. It seeks, and is open to, additional partners for new application development and creates a point of easy open access to the facilities and supply chains that it stimulates or nurtures.

UK National Quantum Technologies Hub in sensors and metrology

The UK National Quantum Technology Hub in Sensors and Metrology is one of four flagship initiatives in the UK National of Quantum Technology Program. As part of a 20-year vision it translates laboratory demonstrations to deployable practical devices, with game-changing miniaturized components and prototypes that transform the state-of-the-art for quantum sensors and metrology. It brings together experts from the Universities of Birmingham, Glasgow, Nottingham, Southampton, Strathclyde and Sussex, NPL and currently links to over 15 leading international academic institutions and over 70 companies to build the supply chains and routes to market needed to bring 10–1000x improvements in sensing applications. It seeks, and is open to, additional partners for new application development and creates a point of easy open access to the facilities and supply chains that it stimulates or nurtures.

Tunable diamond Raman laser intracavity-pumped by an InGaAs semiconductor disk laser

A tunable diamond Raman laser intracavity-pumped within an InGaAs semiconductor disk laser is described. Output power up to 1.3W, conversion efficiency of 14.4%, with M2 ~ 1.1, and tuning from 1209-1245nm are reported.

VECSEL-pumped tunable CW Raman laser

Intracavity pumping of a continuous-wave KGW Raman laser within an InGaAs VECSEL is reported. VECSEL tuning resulted in tunable Raman laser emission from 1136-1154.5nm with total output power up to 120mW.