Method and laser pulse enhancement apparatus for resonantly enhancing pulsed laser light for practical applications and sensitive measurements
Inventors
Fill, Ernst • HOEGNER, Maximilian • Krausz, Ferenc • Pupeza, Ioachim • RAAB, Ann-Kathrin • VORONINA, Liudmila • ZIGMAN, Mihaela
Assignees
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Publication Number
US-12738706-B2
Publication Date
2026-09-15
Expiration Date
Abstract
A method of passively enhancing pulsed laser light by coherent addition of laser pulses in an enhancement cavity (20) comprises the steps of generating a sequence of seed laser pulses (1) with a repetition frequency frep and a frequency comb spectrum (3) comprising frequency comb lines (4) with frequency comb line spacings equal to the repetition frequency frep, coupling the seed laser pulses (1) via a first plate-shaped coupling element (25) into an enhancement cavity (20) comprising at least two cavity mirrors (21, 22, 23, 24) having metallic surfaces and spanning a cavity beam path (26) with a resonator length L, wherein the enhancement cavity (20) has a fundamental transverse mode TEM00 and higher-order transverse cavity modes TEMnm, each with a series of cavity resonance frequencies (5), and a cavity offset frequency (6), and coherent superposition of the seed laser pulses (1) in the enhancement cavity (20), so that at least one enhanced circulating cavity pulse (2) per cavity length is generated, wherein the frequency comb spectrum (3) is a harmonic frequency comb spectrum (3) with a vanishing seeding comb offset frequency, the enhancement cavity (20) is adjusted such that a round-trip carrier-envelope phase slippage of the circulating cavity pulses 2 is equal to 360°/N for the fundamental transverse mode TEM00, N being an integer number equal to or above (2), and a frequency overlap is provided for a plurality of the cavity resonance frequencies (5) with a plurality of the frequency comb lines (4) along the frequency comb spectrum (3). Furthermore, a laser pulse enhancement apparatus and applications thereof, e. g. in field-resolved spectroscopy, are described.
Core Innovation
The invention is a method of passively enhancing pulsed laser light by coherent addition of laser pulses in an enhancement cavity. Seed laser pulses are generated with a repetition frequency and a frequency comb spectrum comprising frequency comb lines spaced by the repetition frequency. The seed laser pulses are coupled via a first plate-shaped coupling element into an enhancement cavity comprising at least two cavity mirrors having metallic surfaces spanning a cavity beam path with a resonator length L.
The enhancement cavity has a fundamental transverse mode and higher-order transverse cavity modes, each with a series of cavity resonance frequencies and a cavity offset frequency. Coherent superposition of the seed laser pulses is used so that at least one enhanced circulating cavity pulse per cavity length is generated. The frequency comb spectrum is a harmonic frequency comb spectrum with a vanishing seeding comb offset frequency, and the enhancement cavity is adjusted such that a round-trip carrier-envelope phase slippage of the circulating cavity pulses is equal to 360°/N for the fundamental transverse mode, where N is an integer number equal to or above 2.
A frequency overlap is provided for a plurality of the cavity resonance frequencies with a plurality of the frequency comb lines along the frequency comb spectrum. The approach includes tuning for overlap by adjusting the resonator length using L*=(c/frep)/N for the fundamental transverse mode, and also includes providing frequency overlap by exciting higher-order transverse cavity modes with n+m+1=N. The use of enhancement cavity mirrors having metallic surfaces supports low dispersion and broadband operation as stated in the summary content provided.
Claims Coverage
The document includes two independent claims: one method claim and one apparatus claim. Across these independent claims, the main inventive features are the passive coherent addition in a metallic-mirror enhancement cavity, the use of a harmonic frequency comb with a vanishing seeding comb offset frequency, and a cavity adjustment condition that enforces round-trip carrier-envelope phase slippage equal to 360°/N along with frequency overlap between cavity resonance frequencies and comb lines.
Coherent addition in a metallic-surface enhancement cavity
A method or apparatus for passively enhancing pulsed laser light by coherent addition of laser pulses in an enhancement cavity comprising at least two cavity mirrors having metallic surfaces and spanning a cavity beam path with resonator length L, the enhancement cavity configured to generate at least one enhanced circulating cavity pulse.
Harmonic frequency comb with vanishing seeding comb offset frequency
Generating seed laser pulses with a repetition frequency and a frequency comb spectrum comprising frequency comb lines with frequency comb line spacings equal to the repetition frequency, where the frequency comb spectrum is a harmonic frequency comb spectrum with a vanishing seeding comb offset frequency.
Round-trip carrier-envelope phase slippage set to 360°/N for the fundamental transverse mode
Adjusting the enhancement cavity such that a round-trip carrier-envelope phase slippage of the circulating cavity pulses is equal to 360°/N for the fundamental transverse mode, with N being an integer number equal to or above 2.
Frequency overlap between cavity resonance frequencies and comb lines
Providing a frequency overlap for a plurality of the cavity resonance frequencies with a plurality of the frequency comb lines along the frequency comb spectrum.
The independent claims define a passive enhancement system that uses coherent addition inside an enhancement cavity with metallic mirror surfaces, employs a harmonic frequency comb with vanishing seeding comb offset frequency, and enforces a carrier-envelope phase slippage condition of 360°/N for overlap between cavity resonance frequencies and frequency comb lines.
Stated Advantages
Supports low dispersion and broadband operation through metallic cavity mirrors, as highlighted in the provided summary content.
Documented Applications
Spectroscopy applications, including field-resolved spectroscopy and trace gas sensing, using enhanced circulating cavity pulses interacting with a sample in a cavity and a detector extracting sample-specific information [procedural detail omitted for safety].
Interested in licensing this patent?