A laser device configured to emit a coherent optical radiation is provided. The laser device has an amplifier system having a single interferometric optical amplification arrangement or a plurality of interferometric optical amplification arrangements in series, an optical return path of an optical beam emerging from the amplifier system and entering the amplifier system to form an optical ring resonant structure, and a radiation output for extracting a portion of the optical beam emerging from the amplifier system and deliver the extracted portion of the optical beam emerging from the amplifier system as output laser radiation of the laser device.

A laser device configured to emit a coherent optical radiation is provided. The laser device has an amplifier system having a single interferometric optical amplification arrangement or a plurality of interferometric optical amplification arrangements in series, an optical return path of an optical beam emerging from the amplifier system and entering the amplifier system to form an optical ring resonant structure, and a radiation output for extracting a portion of the optical beam emerging from the amplifier system and deliver the extracted portion of the optical beam emerging from the amplifier system as output laser radiation of the laser device.

Apparatus for providing optical radiation (15), which apparatus comprises an optical input (13), a coupler (2), a first semiconductor amplifier (3), a controller (4), a preamplifier (61), a power amplifier (62) and an output fibre (5), wherein: the optical input (13) is for receiving input optical radiation (14); the optical input (13) is connected in series to the coupler (2), the first semiconductor amplifier (3), the preamplifier (61), the power amplifier (62), and the output fibre (5); the apparatus being characterized in that: the first semiconductor amplifier (3) comprises a waveguide (6) having a low reflecting facet (8); the first semiconductor amplifier (3) is in a double pass configuration such that the low reflecting facet (8) is connected to both the optical input (13) and the preamplifier (61) via the coupler (2); and the controller (4) is configured to cause the waveguide (6) of the first semiconductor amplifier (3) to operate in saturation thereby enabling the first semiconductor amplifier (3) to reduce non-linear effects in the preamplifier (61), the power amplifier (62), and the output fibre (5).

Apparatus for providing optical radiation (15), which apparatus comprises an optical input (13), a coupler (2), a first semiconductor amplifier (3), a controller (4), a preamplifier (61), a power amplifier (62) and an output fibre (5), wherein: the optical input (13) is for receiving input optical radiation (14); the optical input (13) is connected in series to the coupler (2), the first semiconductor amplifier (3), the preamplifier (61), the power amplifier (62), and the output fibre (5); the apparatus being characterized in that: the first semiconductor amplifier (3) comprises a waveguide (6) having a low reflecting facet (8); the first semiconductor amplifier (3) is in a double pass configuration such that the low reflecting facet (8) is connected to both the optical input (13) and the preamplifier (61) via the coupler (2); and the controller (4) is configured to cause the waveguide (6) of the first semiconductor amplifier (3) to operate in saturation thereby enabling the first semiconductor amplifier (3) to reduce non-linear effects in the preamplifier (61), the power amplifier (62), and the output fibre (5).

A monolithic nonplanar ring oscillator (NPRO) laser with a large piezo-electric tuning range and high frequency slew rate, denoted as a μNPRO, is described. A tuning range of 3.5 GHz with 192 volts applied, corresponding to a tuning coefficient of 18.2 MHz/volt was experimentally demonstrated. This performance was achieved by making the solid-state gain element small, with a small distance between a piezo-electric element bonded to the solid-state gain element and a first lase plane in the solid-state gain element. The entire nonplanar ring lasing path within the solid-state gain element may lie within the half of the solid-state gain element closest to the bonded piezo-electric element. This large frequency modulation span and wide frequency modulation bandwidth, combined with unsurpassed coherence and high power, make this an attractive laser for frequency-modulated continuous-wave (FMCW) LIDAR.

A monolithic nonplanar ring oscillator (NPRO) laser with a large piezo-electric tuning range and high frequency slew rate, denoted as a μNPRO, is described. A tuning range of 3.5 GHz with 192 volts applied, corresponding to a tuning coefficient of 18.2 MHz/volt was experimentally demonstrated. This performance was achieved by making the solid-state gain element small, with a small distance between a piezo-electric element bonded to the solid-state gain element and a first lase plane in the solid-state gain element. The entire nonplanar ring lasing path within the solid-state gain element may lie within the half of the solid-state gain element closest to the bonded piezo-electric element. This large frequency modulation span and wide frequency modulation bandwidth, combined with unsurpassed coherence and high power, make this an attractive laser for frequency-modulated continuous-wave (FMCW) LIDAR.

There is provided a laser, and/or a reflector for a laser cavity comprising: a ring resonator structure; and a Fabry-Perot filter connected in cascade to the ring resonator structure by a coupling waveguide. The coupling waveguide is configured to propagate light having a frequency corresponding to any of the resonant frequencies of the ring resonator structure to the Fabry-Perot filter, and the Fabry-Perot filter is configured to select one or more frequencies and return light having a frequency matching any of the selected frequencies to the ring resonator structure via the coupling waveguide.

There is provided a laser, and/or a reflector for a laser cavity comprising: a ring resonator structure; and a Fabry-Perot filter connected in cascade to the ring resonator structure by a coupling waveguide. The coupling waveguide is configured to propagate light having a frequency corresponding to any of the resonant frequencies of the ring resonator structure to the Fabry-Perot filter, and the Fabry-Perot filter is configured to select one or more frequencies and return light having a frequency matching any of the selected frequencies to the ring resonator structure via the coupling waveguide.

A laser is disclosed having a housing formed of a block of glass-ceramic. The block is machined (or otherwise formed) to define one or more channels that act as a waveguide in two dimensions for light within the laser resonator. The channels extend between cavities also formed within the block which retain optical components of the laser, e.g. one or more of the gain medium, cavity mirrors, intermediate reflectors etc. The positioning, shape and size of each cavity is bespoke for the optical component it holds in order that each optical component is retained in optical alignment rigidly against the sides of the cavity.

A laser is disclosed having a housing formed of a block of glass-ceramic. The block is machined (or otherwise formed) to define one or more channels that act as a waveguide in two dimensions for light within the laser resonator. The channels extend between cavities also formed within the block which retain optical components of the laser, e.g. one or more of the gain medium, cavity mirrors, intermediate reflectors etc. The positioning, shape and size of each cavity is bespoke for the optical component it holds in order that each optical component is retained in optical alignment rigidly against the sides of the cavity.