Yoon-Soo Jang - Academia.edu (original) (raw)

Papers by Yoon-Soo Jang

IEEE Transactions on Instrumentation and Measurement

High-accuracy distance measurements with compact configurations and robust operations are necessa... more High-accuracy distance measurements with compact configurations and robust operations are necessary in areas ranging from precision engineering to scientific missions. Here, we report a precise and accurate amplitude-modulationbased all-fiber distance measurement method without periodic errors. To realize an all-fiber configuration towards on-chip devices in the future, certain selective components for easy fabrication on the chip scale were employed. Despite this constraint, sub-100 nm precision was demonstrated with the help of the all-photonic microwave mixing technique introduced in our previous work. In this paper, accuracy as another important factor for measuring distances was investigated to ensure better performance than in previous studies with an optical amplitudemodulation technique. By performing theoretical and experimental analyses of the periodic error while blocking electrical crosstalk signals and optimizing signal processing, accuracy of 2.6 μm (1 σ) was achieved in terms of measurement linearity according to a comparison with a laser displacement interferometer. With the best capabilities of precision and accuracy, the proposed all-fiber distance measurement method is expected to be utilized in diverse long-distance applications, such as large-machine axis tool work and formation flying by multiple satellites. Further, this study demonstrates the possibility of developing an on-chip-based distance-measuring device for the fourth industrial revolution.

This is an open Access article distributed under the terms of the

Journal of the Korean Society for Precision Engineering

Precision Manufacturing, 2019

arXiv: Instrumentation and Detectors, 2020

Laser interferometry serves a fundamental role in science and technology, assisting precision met... more Laser interferometry serves a fundamental role in science and technology, assisting precision metrology and dimensional length measurement. During the past decade, laser frequency combs - a coherent optical-microwave frequency ruler over a broad spectral range with traceability to time-frequency standards - have contributed pivotal roles in laser dimensional metrology with ever-growing demands in measurement precision. Here we report spectrally-resolved laser dimensional metrology via a soliton frequency microcomb, with nanometric-scale precision. Spectral interferometry provides information on the optical time-of-flight signature, and the large free-spectral range and high-coherence of the microcomb enables tooth-resolved and high-visibility interferograms that can be directly readout with optical spectrum instrumentation. We employ a hybrid timing signal from comb-line homodyne interferometry and microcomb spectrally-resolved interferometry - all from the same spectral interferogr...

2019 Conference on Lasers and Electro-Optics (CLEO), 2019

We present real-time and wide dynamic range measurement of sub-femtometer scale displacement of m... more We present real-time and wide dynamic range measurement of sub-femtometer scale displacement of microcavity. We achieve power spectral density of displacement on the MgF2 whispering gallery mode(WGM)microcavity with sub-femtometer displacement sensitivity. © 2019 The Author(s)

Applied Sciences, 2020

We report an absolute interferometer configured with a 1 GHz microwave source photonically synthe... more We report an absolute interferometer configured with a 1 GHz microwave source photonically synthesized from a fiber mode-locked laser of a 100 MHz pulse repetition rate. Special attention is paid to the identification of the repeatable systematic error with its subsequent suppression by means of passive compensation as well as active correction. Experimental results show that passive compensation permits the measurement error to be less than 7.8 μm (1 σ) over a 2 m range, which further reduces to 3.5 μm (1 σ) by active correction as it is limited ultimately by the phase-resolving power of the phasemeter employed in this study. With precise absolute distance ranging capability, the proposed scheme of the photonic microwave interferometer is expected to replace conventional incremental-type interferometers in diverse long-distance measurement applications, particularly for large machine axis control, precision geodetic surveying and inter-satellite ranging in space.

In this talk, first, we describe chip-scale coherent mode-locking in microresonator frequency com... more In this talk, first, we describe chip-scale coherent mode-locking in microresonator frequency combs, verified by interferometric femtosecond timing jitter measurements and phase-resolved ultrafast spectroscopy. Normal dispersion sub-100-fs mode-locking is also observed, supporting by nonlinear modeling and analytics. Second we describe the noise limits in full microcomb stabilization, locking down both repetition rate and one comb line against a reference. Active stabilization improves the long-term stability to an instrument-limited residual instability of 3.6 mHz per root tau and a tooth-to-tooth relative frequency uncertainty down to 50 mHz and 2.7×10−16. Third we describe graphene-silicon nitride hybrid microresonators for tunable frequency modes, variants of soliton mode-locked states and crystals, and controllable Cerenkov radiation. Our studies provide a platform towards precision spectroscopy, frequency metrology, timing clocks, and coherent communications.

We present sub-fm/Hz1/2 displacement measurement on the MgF2 whispering gallery mode microcavity.... more We present sub-fm/Hz1/2 displacement measurement on the MgF2 whispering gallery mode microcavity. We analyze power spectral density of the displacement from 1 Hz to 100 kHz of the Fourier offset frequency.

We show a resonator long-term temperature stability of 8.53 μK after stabilization and unveil var... more We show a resonator long-term temperature stability of 8.53 μK after stabilization and unveil various sources that hinder the stability from reaching sub- μK in the current system. © 2019 The Author(s)

Physical Review Letters

Section S1. Data processing for the distance metrology Section S2. Stable dual-pump generation of... more Section S1. Data processing for the distance metrology Section S2. Stable dual-pump generation of the single-soliton frequency microcomb Section S3. Repetition rate measurementSection S4. Position calibration of motorized stage by soliton microcomb-based spectrally-resolved interferometry Section S5. Gauge block measurement for 3D surface measurement Section S6. Bounds on the ultimate measurement precision of homodyne interferometry Section S7. Reference against a stabilized mode-locked fiber laser frequency comb Section S8. Characterization of intensity fluctuations on the distance metrology Section S1. Data processing for the distance metrology S1.A. Fundamental minimum and maximum measurement range To determine the distance, the reference and measurement pulse should be separated in the time domain. The minimum measurable distance (Lmin) is determined by pulse duration used in the distance measurement. Lmin can be expressed as Lmin = co/(2Δv), where Δv is a spectrum bandwidth. In our case, Lmin is estimated to be 30 µm considering 5 THz spectrum bandwidth of soliton microcomb. The fundamental maximum measurable distance (Lmax) is upper-bounded by the coherence length of the light source and can be expressed as Lmax = co/(2δv), where δv is the linewidth of the light source. In our case, the Lmax limit is estimated to be 1 km considering the 150 kHz linewidth of soliton microcomb. S1.B. Nonlinear curve fitting for precise peak detection To precisely determine the peak position TOF in time domain, we implement polynomial curve fitting near peak position as I(τ) = Aτ 2 + Bτ + C. Data points for curve fitting are symmetrically chosen with 3 or 5 points around the peak position. The peak position is determined when its first This work Si3N4 microring 88 GHz 6 × 10-8 7 × 10-8

Optics Express

The importance of dimensional metrology has gradually emerged from fundamental research to high-t... more The importance of dimensional metrology has gradually emerged from fundamental research to high-technology industries. In the era of the fourth industrial revolution, absolute distance measurements are required to cope with various applications, such as unmanned vehicles, intelligent robots, and positioning sensors for smart factories. In such cases, the size, weight, power, and cost (SWaP-C) should essentially be restricted. In this paper, sub-100 nm precision distance measurements based on an amplitude-modulated continuous-wave laser (AMCW) with an all-fiber photonic microwave mixing technique is proposed and realized potentially to satisfy SWaP-C requirements. Target distances of 0.879 m and 8.198 m were measured by detecting the phase delay of 15 GHz modulation frequencies. According to our measurement results, the repeatability could reach 43 nm at an average time of 1 s, a result not previously achieved by conventional AMCW laser distance measurement methods. Moreover, the performance by the proposed method in terms of Allan deviation is competitive with most frequency-comb-based absolute distance measurement methods, even with a simple configuration. Because the proposed method has a simple configuration such that it can be easily utilized and demonstrated on a chip-scale platform using CMOS-compatible silicon photonics, it is expected to herald new possibilities, leading to the practical realization of a fully integrated chip-scale LIDAR system.

Conference on Lasers and Electro-Optics

We present ultra-precision distance measurement based on spectral interferometer via single solit... more We present ultra-precision distance measurement based on spectral interferometer via single soliton microcomb generated in Si3N4 microresonator. We demonstrate 3-nm repeatability over a 23-mm non-ambiguity range via homodyne interferometry, over 1000s long-term stability.

Scientific Reports

We report a multi-channel optical frequency synthesizer developed to generate extremely stable co... more We report a multi-channel optical frequency synthesizer developed to generate extremely stable continuous-wave lasers directly out of the optical comb of an Er-doped fiber oscillator. Being stabilized to a high-finesse cavity with a fractional frequency stability of 3.8 × 10 −15 at 0.1 s, the comb-rooted synthesizer produces multiple optical frequencies of ultra-narrow linewidth of 1.0 Hz at 1 s concurrently with an output power of tens of mW per each channel. Diode-based stimulated emission by injection locking is a key mechanism that allows comb frequency modes to sprout up with sufficient power amplification but no loss of original comb frequency stability. Channel frequencies are individually selectable with a 0.1 GHz increment over the entire comb bandwidth spanning 4.25 THz around a 1550 nm center wavelength. A series of out-of-loop test results is discussed to demonstrate that the synthesizer is able to provide stable optical frequencies with the potential for advancing diverse ultra-precision applications such as optical clocks comparison, atomic line spectroscopy, photonic microwaves generation, and coherent optical telecommunications.

International Journal of Precision Engineering and Manufacturing

We report a working prototype of absolute distance meter developed for outer-space operation by i... more We report a working prototype of absolute distance meter developed for outer-space operation by incorporating a fiber-type modelocked laser. The target distance is measured using a 1 GHz synthetic radio frequency (~0.3 m wavelength) provided by the 20th intermode harmonic of a 50 MHz pulse repetition rate. The measurement repeatability is 7 μm at 1 s averaging with an accuracy of ±20 μm for a 2.5 m target distance. With a 100 Hz update rate, the measurement speed is fast enough to keep track of the target in motion with up to a 1.0 m/s velocity. The prototype is built within a compact volume of A4-size footprint to be feasible for the space mission of satellite-to-satellite distance measurement.

International Journal of Precision Engineering and Manufacturing

We review the progress made for compensation of the refractive index of air in laser-based distan... more We review the progress made for compensation of the refractive index of air in laser-based distance measurements in the field of precision engineering. First, a comprehensive analysis is introduced to clarify how the overall measurement uncertainty is affected by the refractive index of the ambient air, particularly for dimensional metrology and geodetic survey using laser in open-air environment. Second, it is explained that the measurement uncertainty can be improved to a 10-8 level by adopting empirical dispersion formulae describing the relation of the laser wavelength with the environment parameters such as temperature, pressure, humidity and carbon dioxide concentration. Third, the principle of refractometers is given to describe that the measurement uncertainty can be enhanced to a 10-9 level by identifying the refractive index of air real time in well-controlled environmental conditions. Fourth, the two-color compensation method is discussed which enables precise laser-based distance measurement simply by using two different wavelengths without actual identification of the refractive index of open air. Finally, the recent approach of using femtosecond lasers is described with emphasis on the performance of the two-color method can be enhanced to a 10-9 level by stabilizing the pulse repetition rate as well as frequency stability of ultrashort pulse lasers with reference to the atomic clocks.

Nanomanufacturing and Metrology

We present a progress review on the advance of distance measurements made at KAIST by making use ... more We present a progress review on the advance of distance measurements made at KAIST by making use of mode-locked lasers as the light source to meet ever-growing industrial demands on the measurement precision and functionality. Diverse principles exploited for the progress are described in this review with focus on four attributes: first, the optical spectrum of a mode-locked laser, distinctively called the frequency comb, permits multi-wavelength interferometry to be realized for absolute distance measurement up to several meters without losing the nanometer precision of well-established laser-based phase-measuring displacement measurement. Second, the frequency comb enables spectrally resolved interferometry for absolute distance measurement to be conducted with a nanometer resolution by Fourier transform analysis of the dispersive interference data captured using a spectrometer. Third, the mode-locked laser in the time domain appears as a train of ultrashort pulses, of which the time-of-flight is measured with a picosecond resolution by control of the pulse repetition rate with reference to the radio-frequency atomic clock. Fourth, the pulse-to-pulse cross-correlation occurring in the optical frequency domain is down-converted to the radio-frequency domain to achieve femtosecond pulse timing precision by means of dual-comb interference. All these principles based on unique spectral and temporal characteristics of ultrashort mode-locked lasers are anticipated to make contributions to the advance of nanotechnology particularly in manufacturing and metrology.

2015 Opto-Electronics and Communications Conference (OECC), 2015

Femtosecond pulse lasers offer breakthroughs in precision metrology particularly in the fields of... more Femtosecond pulse lasers offer breakthroughs in precision metrology particularly in the fields of time, distance and spectroscopy. This advance attracts much attention to extend today's space missions by improving the precision of remote sensing and control capabilities. In this presentation, we introduce how femtosecond lasers are being investigated for space explorations in the near future.

IEEE Transactions on Instrumentation and Measurement

High-accuracy distance measurements with compact configurations and robust operations are necessa... more High-accuracy distance measurements with compact configurations and robust operations are necessary in areas ranging from precision engineering to scientific missions. Here, we report a precise and accurate amplitude-modulationbased all-fiber distance measurement method without periodic errors. To realize an all-fiber configuration towards on-chip devices in the future, certain selective components for easy fabrication on the chip scale were employed. Despite this constraint, sub-100 nm precision was demonstrated with the help of the all-photonic microwave mixing technique introduced in our previous work. In this paper, accuracy as another important factor for measuring distances was investigated to ensure better performance than in previous studies with an optical amplitudemodulation technique. By performing theoretical and experimental analyses of the periodic error while blocking electrical crosstalk signals and optimizing signal processing, accuracy of 2.6 μm (1 σ) was achieved in terms of measurement linearity according to a comparison with a laser displacement interferometer. With the best capabilities of precision and accuracy, the proposed all-fiber distance measurement method is expected to be utilized in diverse long-distance applications, such as large-machine axis tool work and formation flying by multiple satellites. Further, this study demonstrates the possibility of developing an on-chip-based distance-measuring device for the fourth industrial revolution.

This is an open Access article distributed under the terms of the

Journal of the Korean Society for Precision Engineering

Precision Manufacturing, 2019

arXiv: Instrumentation and Detectors, 2020

Laser interferometry serves a fundamental role in science and technology, assisting precision met... more Laser interferometry serves a fundamental role in science and technology, assisting precision metrology and dimensional length measurement. During the past decade, laser frequency combs - a coherent optical-microwave frequency ruler over a broad spectral range with traceability to time-frequency standards - have contributed pivotal roles in laser dimensional metrology with ever-growing demands in measurement precision. Here we report spectrally-resolved laser dimensional metrology via a soliton frequency microcomb, with nanometric-scale precision. Spectral interferometry provides information on the optical time-of-flight signature, and the large free-spectral range and high-coherence of the microcomb enables tooth-resolved and high-visibility interferograms that can be directly readout with optical spectrum instrumentation. We employ a hybrid timing signal from comb-line homodyne interferometry and microcomb spectrally-resolved interferometry - all from the same spectral interferogr...

2019 Conference on Lasers and Electro-Optics (CLEO), 2019

We present real-time and wide dynamic range measurement of sub-femtometer scale displacement of m... more We present real-time and wide dynamic range measurement of sub-femtometer scale displacement of microcavity. We achieve power spectral density of displacement on the MgF2 whispering gallery mode(WGM)microcavity with sub-femtometer displacement sensitivity. © 2019 The Author(s)

Applied Sciences, 2020

We report an absolute interferometer configured with a 1 GHz microwave source photonically synthe... more We report an absolute interferometer configured with a 1 GHz microwave source photonically synthesized from a fiber mode-locked laser of a 100 MHz pulse repetition rate. Special attention is paid to the identification of the repeatable systematic error with its subsequent suppression by means of passive compensation as well as active correction. Experimental results show that passive compensation permits the measurement error to be less than 7.8 μm (1 σ) over a 2 m range, which further reduces to 3.5 μm (1 σ) by active correction as it is limited ultimately by the phase-resolving power of the phasemeter employed in this study. With precise absolute distance ranging capability, the proposed scheme of the photonic microwave interferometer is expected to replace conventional incremental-type interferometers in diverse long-distance measurement applications, particularly for large machine axis control, precision geodetic surveying and inter-satellite ranging in space.

In this talk, first, we describe chip-scale coherent mode-locking in microresonator frequency com... more In this talk, first, we describe chip-scale coherent mode-locking in microresonator frequency combs, verified by interferometric femtosecond timing jitter measurements and phase-resolved ultrafast spectroscopy. Normal dispersion sub-100-fs mode-locking is also observed, supporting by nonlinear modeling and analytics. Second we describe the noise limits in full microcomb stabilization, locking down both repetition rate and one comb line against a reference. Active stabilization improves the long-term stability to an instrument-limited residual instability of 3.6 mHz per root tau and a tooth-to-tooth relative frequency uncertainty down to 50 mHz and 2.7×10−16. Third we describe graphene-silicon nitride hybrid microresonators for tunable frequency modes, variants of soliton mode-locked states and crystals, and controllable Cerenkov radiation. Our studies provide a platform towards precision spectroscopy, frequency metrology, timing clocks, and coherent communications.

We present sub-fm/Hz1/2 displacement measurement on the MgF2 whispering gallery mode microcavity.... more We present sub-fm/Hz1/2 displacement measurement on the MgF2 whispering gallery mode microcavity. We analyze power spectral density of the displacement from 1 Hz to 100 kHz of the Fourier offset frequency.

We show a resonator long-term temperature stability of 8.53 μK after stabilization and unveil var... more We show a resonator long-term temperature stability of 8.53 μK after stabilization and unveil various sources that hinder the stability from reaching sub- μK in the current system. © 2019 The Author(s)

Physical Review Letters

Section S1. Data processing for the distance metrology Section S2. Stable dual-pump generation of... more Section S1. Data processing for the distance metrology Section S2. Stable dual-pump generation of the single-soliton frequency microcomb Section S3. Repetition rate measurementSection S4. Position calibration of motorized stage by soliton microcomb-based spectrally-resolved interferometry Section S5. Gauge block measurement for 3D surface measurement Section S6. Bounds on the ultimate measurement precision of homodyne interferometry Section S7. Reference against a stabilized mode-locked fiber laser frequency comb Section S8. Characterization of intensity fluctuations on the distance metrology Section S1. Data processing for the distance metrology S1.A. Fundamental minimum and maximum measurement range To determine the distance, the reference and measurement pulse should be separated in the time domain. The minimum measurable distance (Lmin) is determined by pulse duration used in the distance measurement. Lmin can be expressed as Lmin = co/(2Δv), where Δv is a spectrum bandwidth. In our case, Lmin is estimated to be 30 µm considering 5 THz spectrum bandwidth of soliton microcomb. The fundamental maximum measurable distance (Lmax) is upper-bounded by the coherence length of the light source and can be expressed as Lmax = co/(2δv), where δv is the linewidth of the light source. In our case, the Lmax limit is estimated to be 1 km considering the 150 kHz linewidth of soliton microcomb. S1.B. Nonlinear curve fitting for precise peak detection To precisely determine the peak position TOF in time domain, we implement polynomial curve fitting near peak position as I(τ) = Aτ 2 + Bτ + C. Data points for curve fitting are symmetrically chosen with 3 or 5 points around the peak position. The peak position is determined when its first This work Si3N4 microring 88 GHz 6 × 10-8 7 × 10-8

Optics Express

The importance of dimensional metrology has gradually emerged from fundamental research to high-t... more The importance of dimensional metrology has gradually emerged from fundamental research to high-technology industries. In the era of the fourth industrial revolution, absolute distance measurements are required to cope with various applications, such as unmanned vehicles, intelligent robots, and positioning sensors for smart factories. In such cases, the size, weight, power, and cost (SWaP-C) should essentially be restricted. In this paper, sub-100 nm precision distance measurements based on an amplitude-modulated continuous-wave laser (AMCW) with an all-fiber photonic microwave mixing technique is proposed and realized potentially to satisfy SWaP-C requirements. Target distances of 0.879 m and 8.198 m were measured by detecting the phase delay of 15 GHz modulation frequencies. According to our measurement results, the repeatability could reach 43 nm at an average time of 1 s, a result not previously achieved by conventional AMCW laser distance measurement methods. Moreover, the performance by the proposed method in terms of Allan deviation is competitive with most frequency-comb-based absolute distance measurement methods, even with a simple configuration. Because the proposed method has a simple configuration such that it can be easily utilized and demonstrated on a chip-scale platform using CMOS-compatible silicon photonics, it is expected to herald new possibilities, leading to the practical realization of a fully integrated chip-scale LIDAR system.

Conference on Lasers and Electro-Optics

We present ultra-precision distance measurement based on spectral interferometer via single solit... more We present ultra-precision distance measurement based on spectral interferometer via single soliton microcomb generated in Si3N4 microresonator. We demonstrate 3-nm repeatability over a 23-mm non-ambiguity range via homodyne interferometry, over 1000s long-term stability.

Scientific Reports

We report a multi-channel optical frequency synthesizer developed to generate extremely stable co... more We report a multi-channel optical frequency synthesizer developed to generate extremely stable continuous-wave lasers directly out of the optical comb of an Er-doped fiber oscillator. Being stabilized to a high-finesse cavity with a fractional frequency stability of 3.8 × 10 −15 at 0.1 s, the comb-rooted synthesizer produces multiple optical frequencies of ultra-narrow linewidth of 1.0 Hz at 1 s concurrently with an output power of tens of mW per each channel. Diode-based stimulated emission by injection locking is a key mechanism that allows comb frequency modes to sprout up with sufficient power amplification but no loss of original comb frequency stability. Channel frequencies are individually selectable with a 0.1 GHz increment over the entire comb bandwidth spanning 4.25 THz around a 1550 nm center wavelength. A series of out-of-loop test results is discussed to demonstrate that the synthesizer is able to provide stable optical frequencies with the potential for advancing diverse ultra-precision applications such as optical clocks comparison, atomic line spectroscopy, photonic microwaves generation, and coherent optical telecommunications.

International Journal of Precision Engineering and Manufacturing

We report a working prototype of absolute distance meter developed for outer-space operation by i... more We report a working prototype of absolute distance meter developed for outer-space operation by incorporating a fiber-type modelocked laser. The target distance is measured using a 1 GHz synthetic radio frequency (~0.3 m wavelength) provided by the 20th intermode harmonic of a 50 MHz pulse repetition rate. The measurement repeatability is 7 μm at 1 s averaging with an accuracy of ±20 μm for a 2.5 m target distance. With a 100 Hz update rate, the measurement speed is fast enough to keep track of the target in motion with up to a 1.0 m/s velocity. The prototype is built within a compact volume of A4-size footprint to be feasible for the space mission of satellite-to-satellite distance measurement.

International Journal of Precision Engineering and Manufacturing

We review the progress made for compensation of the refractive index of air in laser-based distan... more We review the progress made for compensation of the refractive index of air in laser-based distance measurements in the field of precision engineering. First, a comprehensive analysis is introduced to clarify how the overall measurement uncertainty is affected by the refractive index of the ambient air, particularly for dimensional metrology and geodetic survey using laser in open-air environment. Second, it is explained that the measurement uncertainty can be improved to a 10-8 level by adopting empirical dispersion formulae describing the relation of the laser wavelength with the environment parameters such as temperature, pressure, humidity and carbon dioxide concentration. Third, the principle of refractometers is given to describe that the measurement uncertainty can be enhanced to a 10-9 level by identifying the refractive index of air real time in well-controlled environmental conditions. Fourth, the two-color compensation method is discussed which enables precise laser-based distance measurement simply by using two different wavelengths without actual identification of the refractive index of open air. Finally, the recent approach of using femtosecond lasers is described with emphasis on the performance of the two-color method can be enhanced to a 10-9 level by stabilizing the pulse repetition rate as well as frequency stability of ultrashort pulse lasers with reference to the atomic clocks.

Nanomanufacturing and Metrology

We present a progress review on the advance of distance measurements made at KAIST by making use ... more We present a progress review on the advance of distance measurements made at KAIST by making use of mode-locked lasers as the light source to meet ever-growing industrial demands on the measurement precision and functionality. Diverse principles exploited for the progress are described in this review with focus on four attributes: first, the optical spectrum of a mode-locked laser, distinctively called the frequency comb, permits multi-wavelength interferometry to be realized for absolute distance measurement up to several meters without losing the nanometer precision of well-established laser-based phase-measuring displacement measurement. Second, the frequency comb enables spectrally resolved interferometry for absolute distance measurement to be conducted with a nanometer resolution by Fourier transform analysis of the dispersive interference data captured using a spectrometer. Third, the mode-locked laser in the time domain appears as a train of ultrashort pulses, of which the time-of-flight is measured with a picosecond resolution by control of the pulse repetition rate with reference to the radio-frequency atomic clock. Fourth, the pulse-to-pulse cross-correlation occurring in the optical frequency domain is down-converted to the radio-frequency domain to achieve femtosecond pulse timing precision by means of dual-comb interference. All these principles based on unique spectral and temporal characteristics of ultrashort mode-locked lasers are anticipated to make contributions to the advance of nanotechnology particularly in manufacturing and metrology.

2015 Opto-Electronics and Communications Conference (OECC), 2015

Femtosecond pulse lasers offer breakthroughs in precision metrology particularly in the fields of... more Femtosecond pulse lasers offer breakthroughs in precision metrology particularly in the fields of time, distance and spectroscopy. This advance attracts much attention to extend today's space missions by improving the precision of remote sensing and control capabilities. In this presentation, we introduce how femtosecond lasers are being investigated for space explorations in the near future.