Pulsed Electromagnetic-Wave Generator for Fast Terahertz Frequency Switching
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Solution Overview
Problem
Conventional terahertz wave generators using solid state lasers have limited frequency switching speed, leading to degradation in measurement accuracy when measuring substances that change concentration with environmental conditions, due to the restriction of repetition frequency.
Innovation Solution
A pulsed electromagnetic-wave generator employing a microchip laser that oscillates multiple high-peak-power short pulses at different frequencies and times, utilizing a wavelength converting unit with a nonlinear optical crystal for terahertz-wave generation, allowing for faster frequency switching without a wavelength variable function for the seed light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a solid state laser is used for is-TPG to generate terahertz waves, then high peak power can be achieved, but the frequency switching speed is restricted by the repetition frequency of the laser
Solution Approach 1:
The patent applies periodic action by using a pulsed laser source that generates multiple pulses within a single excitation cycle. The laser operates in a periodic manner, creating a sequence of pulses with different frequencies at different time points within each period, thereby achieving fast frequency switching without being limited by the overall repetition frequency of the laser system.
Solution Approach 2:
The patent implements dynamics by enabling the laser frequency to vary dynamically within each excitation cycle. The frequency of the laser is modulated or tuned across multiple values during the pulse train, allowing the system to access different terahertz frequencies rapidly. This dynamic frequency adjustment resolves the contradiction by making the frequency switching speed independent of the laser's fundamental repetition rate.
2Measurement precision
If the repetition frequency of the solid state laser is increased to improve frequency switching speed, then measurement accuracy can be improved, but the laser system becomes more complex and difficult to control
Solution Approach 1:
The patent uses periodic action to generate multiple measurement points within a single laser excitation cycle. By creating a train of pulses with different frequencies during one period, the system achieves high measurement accuracy for time-varying samples without needing to increase the overall repetition frequency, thus avoiding increased system complexity.
3Stability of the object's composition
If frequency switching is performed slowly, then the laser system remains stable and simple to operate, but measurement accuracy degrades when measuring substances that change concentration with environmental conditions
Solution Approach 1:
The patent resolves this contradiction by performing multiple frequency measurements periodically within a single stable laser excitation cycle. The laser maintains stable operating conditions while generating a periodic train of pulses at different frequencies, allowing accurate measurement of time-varying samples without compromising system stability or requiring complex frequency tuning mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the generation of multiple terahertz-wave pulses with different frequencies at short time intervals, improving measurement accuracy by acquiring multiple frequency information points quickly and simplifying system structure, while preventing measurement accuracy degradation due to environmental changes.
Implementation Method 1
the injection-seeded terahertz-wave parametric generation (is-TPG) that uses nonlinear optical effects
Implementation Method 2
The frequency of the terahertz wave generated by is-TPG is determined based on a frequency difference of pump light and seed light that enter a nonlinear optical crystal
Implementation Method 3
The pulse generating unit is configured to generate a pulsed light group including at least two or more pulses with different frequencies (ω) and different oscillation timings (t)
Data Source
AI summary
A pulsed electromagnetic-wave generator includes an excitation light source, a laser resonator, a pulse generating unit, and a wavelength converting unit. Excitation light from the excitation light source enters the laser resonator. The pulse generating unit is configured to generate a pulsed light group including at least two or more pulses with different frequencies (ω) and different oscillation timings (t) in one excitation process of the excitation light source, an oscillation frequency difference (Δω) between the pulses in the pulsed light group being an integral multiple of a Free Spectral Range (FSR) of the laser resonator. The pulsed light group enters the wavelength converting unit. The wavelength converting unit is configured to generate a pulsed electromagnetic wave in which a wavelength of each pulse in the pulsed light group is converted.