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Highly efficient Tm-Ho co-doped ultrashort pulse fiber laser operating at 1.9 μm was developed using single wall carbon nanotube. Wideband supercontinuum at 2.0 μm was generated and high-resolution OCT imaging of human tooth was demonstrated.

Spectral peaking during supercontinuum generation in normal dispersive highly nonlinear fiber was investigated both numerically and experimentally. Sharp multiple spectral peaks were generated stably with 290 GHz frequency interval, and low noise properties were confirmed.

Wideband, octave spanning, coherent supercontinuum (SC) with high flatness is very useful for many applications, but it has been difficult to achieve such ideal SC. In this paper, we investigated the octave spanning, coherent SC generation based on Er-doped ultrashort pulse fiber laser system. First, we developed a high power ultrashort pulse system using a single-wall carbon nanotube fiber laser and similariton amplifier. A 1.0–2.2 μ m octave-spanning coherent supercontinuum was successfully generated. Next, by use of a stabilized fiber laser comb system as the seed pulse, an octave spanning SC comb was demonstrated. An octave spanning, highly coherent comb with high flatness was generated with normally dispersive highly nonlinear fiber. The characteristics of the generated supercontinuum comb were examined via balanced heterodyne beat measurements with stable continuous-wave laser diodes. The SC comb was confirmed to have high coherence and low amplitude noise at the observed wavelengths. Finally, the SC generation in two kinds of highly nonlinear fibers with different dispersion properties and the characteristics of the generated comb were examined. The dependence on fiber length, wavelength, and dispersion properties were discussed.

An offset-free, wavelength-tunable, and midinfrared frequency comb working at 184 MHz based on difference frequency generation (DFG) in a PPMgSLT crystal was demonstrated. A coherent Raman soliton pulse and Yb-fiber laser output were used as the seed pulses of DFG, and wavelength tunability in the range 3.1–5.2 μ m was realized. A quantum cascade laser stabilized by the absorption line of N2O was used to measure the beat signal with an MIR comb. The MIR comb had a good spatial beam profile, and a high signal-to-noise ratio (SNR) of 70 dB at a wavelength of 4.52 μ m was confirmed. A stable and sharp beat signal was observed in the MIR region with a linewidth of 160 kHz, and the SNR was larger than 20 dB.

Optical coherence tomography (OCT) is a non-invasive cross-sectional imaging technique with micrometer resolution. OCT is useful, non-invasive imaging technique of the internal structure, and it has been applied in many fields, especially medicine and industry. The theoretical axial resolution is determined by the center wavelength and bandwidth of the light source, and the wider the bandwidth is, the higher the axial resolution is. Supercontinuum is the high-power, ultrawideband light source. We have been investigating ultrahigh-resolution (UHR)-OCT using supercontinuum. The characteristics of OCT imaging depend on the optical wavelength used. In this talk, we report our recent work of the wavelength dependence of UHR-OCT using a supercontinuum for biomedical imaging. In order to investigate the wavelength dependence of UHR-OCT, the wideband, high-power, low-noise supercontinua were generated at wavelengths of 0.8, 1.1, 1.3, and 1.7 um based on ultrashort pulses and nonlinear fibers. The wavelength dependence of OCT imaging was examined quantitatively using biological phantoms. Ultrahigh-resolution imaging of a rat lung was demonstrated with wavelengths of 0.8 – 1.0 um UHR-OCT. The variation of alveolar volume was estimated using 3D image analysis. We also developed UHR-spectral domain-OCT and optical coherence microscopy (OCM) at 1.7 um. The high-resolution and high-penetration imaging of turbid tissue, especially mouse brain, was demonstrated. The wavelength dependence of OCM was also discussed in terms of mouse brain imaging.

We developed 1.6-1.7 um wavelength tunable, polarization-maintaining dual comb fiber laser. Spectral width was controlled and wideband measurement was realized without bandpass filters. Absorption spectra of CH4 gas was observed in this wide range.

We present three-dimensional (3-D) high-resolution spectral-domain optical coherence microscopy (SD-OCM) by using a supercontinuum (SC) fiber laser source with 300-nm spectral bandwidth (full-width at half-maximum) in the 1700-nm spectral band. By using low-coherence interferometry with SC light and a confocal detection scheme, we realized lateral and axial resolutions of 3.4 and 3.8 μm in tissue (n=1.38), respectively. This is, to the best of our knowledge, the highest 3-D spatial resolution reported among those of Fourier-domain optical coherence imaging techniques in the 1700-nm spectral band. In our SD-OCM, to enhance the imaging depth, a full-range method was implemented, which suppressed the formation of a coherent ghost image and allowed us to set the zero-delay position inside the samples. We demonstrated the 3-D high-resolution imaging capability of 1700-nm SD-OCM through the measurement of an interference signal from a mirror surface and imaging of a single 200-nm polystyrene bead and a pig thyroid gland. Deep tissue imaging at a depth of up to 1.8 mm was also demonstrated. This is the first demonstration of 3-D high-resolution SD-OCM in the 1700-nm spectral band.

We demonstrated a dispersion-managed, high-power, Tm-doped ultrashort pulse fiber laser using a single-wall-carbon-nanotube (SWNT) polyimide film. SWNTs with a diameter of 1.6 nm were synthesized with the enhanced direct injection pyrolytic synthesis (e-DIPs) method, and thin polyimide films in which SWNTs were dispersed were developed as saturable absorbers in the wavelength range λ = 1.8–2.0 µm. An all-fiber type, passively mode-locked, ultrashort-pulse Tm-doped fiber laser was demonstrated using the developed SWNT films. Wavelength tuning operation with gain fiber control and dispersion management of the developed fiber laser were investigated. Stable soliton and dissipative soliton mode locking operations were observed. High-power (102.6 mW) single-pulse mode-locking operation was achieved in a large positive dispersion regime. The repetition rate was 21.6 MHz, and the corresponding pulse energy was 4.75 nJ. To the best of our knowledge, this is the highest power operation of a Tm-doped fiber laser using carbon nanotubes and film-type devices with nano-carbon materials. The developed laser showed self-staring, stable performance and is useful for practical applications.

1.6-1.95 μm wavelength tunable, narrow linewidth comb was generated in two different schemes. Comb properties with high SNR were experimentally confirmed using heterodyne beat measurement with cw-LD, and dual comb beat measurement with supercontinuum comb

Bi-directional, Er-doped dual comb fiber laser was demonstrated using polyimide film dispersed with single wall carbon nanotube. Difference of repetition frequency was temporally stable and it could be tuned continuously by pump power control.

Figure-nine fiber lasers can realize all-polarization-maintaining, self-started, highly stable mode-locked laser sources, and are very attractive for applications such as optical frequency combs, metrology, etc. In this work, we investigated a dispersion-managed, polarization-maintaining, Er-doped, ultrashort-pulse figure-nine fiber laser both experimentally and numerically. Stable, self-started, passive mode-locking operation was achieved in a wide net cavity dispersion region, covering the soliton, stretched pulse, and dissipative soliton mode-locking regimes. A 132 fs ultrashort pulse with spectral width of 46 nm was obtained in the stretched pulse mode-locking regime. The initial mode-locking process and dynamics inside the cavity, in addition to the fundamental characteristics of the output pulses, were examined via numerical analysis. Owing to the asymmetric configuration, the propagation behaviors were different between the two counter-propagation directions. It was found that a large breathing had already started before the passive mode-locking point in stretched pulse mode-locking operation. Intense overshoots were also observed at the beginning of passive mode-locking. Numerical results were almost in agreement with the experimental ones.

We demonstrated a bi-directional, Er-doped dual comb fiber laser consisting of all-polarization-maintaining fiber devices. Polyimide films in which single-wall carbon nanotubes (SWNTs) were dispersed were used as the in-line saturable absorber. In order to avoid synchronization of the two combs and associated damage to the SWNT film, a two-branch configuration with two SWNT films was employed. Soliton pulses with almost the same optical spectra were generated stably in each direction, and dual comb beats were observed simply by overlapping the two outputs. The repetition frequency was 28 MHz, and the frequency difference was 105-140 Hz. Thanks to the small frequency difference, dual comb beats corresponding to the whole optical spectrum were observed without any overlapping. Fourier transform spectroscopy using the developed dual comb source was examined, and the characteristics of an optical filter were successfully obtained.

A Gaussian-like supercontinuum with a bandwidth of 180-nm in 2.1-µm wavelength was generated with an Er-doped fiber laser, Tm-doped fiber amplifier, and highly nonlinear fiber. The seed pulse was generated by Raman soliton effect.

Stable operation of all polarization maintaining optical frequency comb was demonstrated based on Er-doped ultrashort pulse fiber laser with carbon nanotube. The fceo and frep were stabilized and standard deviation of frep was 3.4 mHz.

Offset free mid-infrared optical frequency comb at 4.52 μm was generated through DFG pumped by Yb-doped fiber laser system. Narrow RF beat between MIR comb and quantum cascade laser was observed with high SNR.

All polarization maintaining optical frequency comb was demonstrated based on Er-doped ultrashort pulse fiber laser with carbon nanotube. The f ceo and f rep were stabilized and their linewidths were compressed below 1 Hz by phase locking.

Offset free, 4.4–5.2 μm wavelength tunable, mid-infrared optical frequency comb was generated through DFG pumped by Yb-doped fiber laser system. Coherence verification was performed by beat-note measurement using quantum cascade laser.

Octave spanning supercontinuum comb generation was demonstrated using stabilized fiber laser comb, and highly nonlinear normal dispersive and zero dispersive fibers. Characteristics of spectral shape and coherence were examined and fiber length dependence was discussed.

Supercontinuum is useful light source for ultrahigh resolution optical coherence tomography (OCT) imaging. In this talk, the recent investigations about ultrahigh resolution OCT imaging using supercontinuum and their wavelength dependence are reviewed.

We investigated the characteristics and behavior of spectral compression in a quasi-dispersion-increasing comb-profile fiber (CPF). A periodical breathing behavior and sidelobe emission process in the CPF were observed in numerical analysis. Then, taking account of the numerical results, we developed an improved CPF in which the sidelobe suppression was dramatically improved to −24.2 dB while keeping a narrow spectral width of ~0.6 nm. As a seed pulse source, we developed a high-repetition-rate Er-doped ultrashort-pulse fiber laser with single-wall carbon nanotubes and used the improved CPF to realize a high-power, narrow-linewidth source with wide wavelength tunability in the 1.62–1.90 μm band.

Ultrawideband supercontinua have been generated using ultrashort pulses and zero-dispersion highly nonlinear fiber. However, they have inherent large noise and spectral fine structure. We generated a widely and flatly broadened, low-noise, highly coherent, high-quality supercontinuum and used it to demonstrate ultrahigh-resolution optical coherence tomography in several wavelength regions.

Using the optical fibers and ultrashort pulses, we can demonstrate highly functional optical control. We have succeeded in generation of low-noise, ultraflat, high-quality supercontinuum (SC). Recently, octave spanning high-quality SC is also generated. The carrier envelope offset frequency measurement and ultrahigh resolution optical coherence tomography are demonstrated using SC. We can also generate widely wavelength-tunable ultrashort soliton pulses using soliton self-frequency shift (SSFS). So far, several new techniques have been proposed and demonstrated using SSFS. The author has also discovered novel two-pulse trapping phenomena. The ultrafast all-optical switching is demonstrated using the pulse trapping techniques, and principles and characteristics are described.

We presented a three-dimensional optical memory using a newly developed compact fiber laser. The fiber laser can produce pulse with high peak power of 5.3 kW. This allows two-photon absorption recording for next generation optical recording media possible for consumer application. We demonstrated two-photon absorption recording on a photochromic materials; diarylethene and achieved multilayer recording using the developed fiber laser.

Wideband wavelength tunable narrow linewidth source was demonstrated with comb profiled fiber and Er-doped ultrashort pulse fiber laser with single wall carbon nanotube. Dramatic improvement of sidelobe suppression was achieved with improved comb profiled fibers.

A highly coherent mid-infrared optical frequency comb was generated through DFG pumped by supercontinuum from Yb-doped fiber laser system. MIR wavelength can be tuned continuously from 2.9 to 4.7 μm by a delay line.

Octave spanning, coherent supercontinuum comb with high flatness was realized with normal dispersion highly nonlinear fiber, similariton amplifier, and stabilized Er-doped fiber laser comb. Highly coherent properties were confirmed after 1.4 km fiber delivery.

We have been investigating highly functional ultrashort pulse fiber laser sources for highly sensitive, ultrahigh resolution optical coherence tomography (UHR-OCT). The coherent, low-noise, and Gaussian like wideband super-continuum (SC) sources were developed at five different wavelength regions between 0.8 and 1.7 um in order to investigate the wavelength dependence of OCT imaging. A real-time imaging was achieved with spectral domain OCT system. A fiber laser based, rapid, widely wavelength tunable narrow linewidth source was also developed. The UHR-OCT imaging of biological samples were demonstrated using the developed OCT systems.

We investigated the dynamics of a dispersion-managed, passively mode-locked, ultrashort-pulse, Er-doped fiber laser using a single-wall carbon nanotube (SWNT) device. A numerical model was constructed for analysis of the SWNT fiber laser. The initial process of passive mode-locking, the characteristics of the output pulse, and the dynamics inside the cavity were investigated numerically for soliton, dissipative-soliton, and stretched-pulse mode-locking conditions. The dependencies on the total dispersion and recovery time of the SWNTs were also examined. Numerical results showed similar behavior to experimental results.

Optical coherence tomography is an optical imaging technique that performs non-destructive cross-sectional imaging of micrometer-scale structures in samples. In this report, we demonstrated the visualization of inner structures in tomato fruits and leaves with ultra-high resolution optical coherence tomography (UHR-OCT) using fiber based laser source with ultra-broadband continuous spectrum around 1.7 μm wavelength. We confirmed that our UHR-OCT system allows us to perform cross-sectional imaging of tomato fruits and leaves at ∼ 2.8 μm axial resolution.

We present an all-fiber system for generating pedestal-free 22-fs ultrashort pulses with a single-peak spectrum. High-power Raman soliton pulses and a normally dispersive highly nonlinear fiber are used to generate a smooth, broadened single-peak spectrum. Then, the higher order dispersion is compensated for using a hybrid fiber composed of a reverse-dispersion fiber and a standard single-mode fiber, which allows pedestal-free ultrashort pulses to be successfully generated. To our knowledge, this is the first demonstration of pedestal-free 20-fs-class ultrashort pulse generation without spectral distortion using an all-fiber configuration.

The generation of supercontinuum spectra from the injection of femtosecond pulses into microstructure or tapered fibers has now been achieved by several groups [1, 2]. In 2001, we generated a supercontinuum around 1.55 µm by injecting a 100-fs-duration fiber laser pulse with a 1-nJ pulse energy into a 5-m-long highly nonlinear dispersion-shifted fiber. The supercontinuum is a remarkable light source for applications in many fields due to its extreme spectral broadness and simple generation scheme. These unique properties should make the supercontinuum an ideal tool for important applications, including WDM telecommunications, optical coherence tomography, and optical-frequency measurement. However, significant broadband noise on the supercontinuum has been observed, limiting its stability, so that the supercontinuum is too noisy for many applications. In this study, we experimentally analyze the correlation among supercontinuum spectra that contribute to increasing and decreasing this noise by spectral filtering using spatial light modulator. We observed the formation of correlations among supercontinuum spectra for two fibers which have different properties for chromatic dispersion. We also discuss how nonlinear effects act on the formation of correlations. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(3): 55–60, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20435

The broadband supercontinuum (SC) with high coherence enables to realize the accurate optical frequency standard. We generate the SC from 1200 nm to 2200 nm using the polarization maintaining highly nonlinear dispersion shifted fiber (PM-HNL-DSF). It is expected that coherence can be complicated because of the fluctuations in the input pulse. We measure coherence as a function of wavelength across the SC spectrum by using the interferometer. The interference fringes can be observed and degree of coherence is calculated with their peak value of them. In case of the short fiber, degree of coherence is independently of the input power. On the other hand, in case of the long fiber, degree of coherence degrades and the spectral fine structure arises as the input power increases. We also analyze the coherence of SC with numerical simulations using the nonlinear Schrodinger equation and numerical results are similar to the experimental ones. The spectral fine structure which is the results of the cross-phase modulation (XPM) can affect coherence degradation because it is very sensitive to the fluctuations in the input pulse.

The 0.78–1.0 µm wavelength-tunable femtosecond soliton pulse generation is demonstrated using a fiber laser, periodically poled LiNbO3 and photonic crystal fibers (PCFs). The wavelengths of the generated pulses are varied continuously and monotonically simply by varying the fiber input power. The temporal widths of the generated pulses are about 55 and 94 fs for 0.6 and 2 m of PCFs, respectively. The generated pulses are pedestal-free clear pulses and the corresponding time-bandwidth products are about 0.38. Characteristics of generated soliton pulses are analyzed using the extended nonlinear Schrodinger equation and the numerical results are almost in agreement with the experimental ones. This system is very compact and useful for practical applications. When 2 m of PCF is used, generation of anti-stokes pulse at the shorter wavelength side of the pump pulse is observed.

Compact system of wavelength tunable ultrashort soliton pulse generation has been demonstratedusing modelockedfemtosecond fiber laser and polarization maintaining (PM) fiber. The wavelengths of generated pulsescan be changed continuously by merely varying fiber input power. The generated pulses are almost transformlimited ideal soliton pulses. Two-colored soliton pulses can be generated simultaneously usingthe birefringenceof PM fibers. Using the dispersion shifted PM fibers, in addition to the soliton pulse, the anti-stokespulse is generated at the shorter wavelength side. Using the diameter reduced PM fibers and dispersion shiftedPM fibers, the wavelength tunable ultrashort pulses can be generated in the wide wavelength region of 1.3-2.0μm. In this paper, the characteristics of wavelength tunable soliton pulse are described withthe principles and applications.

We have investigated both experimentally and numerically the characteristics of wavelength tunable femtosecond soliton pulse generation using a pulse width variable fiber laser and two different types of polarization maintaining fibers. The generated soliton shows the feature of the pulsewidth becoming almost constant at - 250 fs under any conditions of the pump pulse for 220m fiber. High conversion efficiency from pump pulse to a generated soliton pulse accounting for as much as 73% can be obtained. This efficiency decreases with increase in the input power or wavelength shift. A superior conversion efficiency and broad wavelength shift can be obtained by using a more shortened pump pulse. In the numerical calculations, it is predicted that under a condition of constant power of pump pulse, the maximum wavelength shift is achieved when the soliton number N is -1.4. The difference of mode field diameter and the group velocity dispersion (GVD) coefficient β2 affect the wavelength shift and conversion efficiency. Using the fiber with small mode field diameter and small absolute value of GVD coefficient β2, a high conversion efficiency and large wavelength shift can be obtained.

We developed a compact and high-power mode-locked fiber laser for three-dimensional optical memory. Fiber lasers have the potential to be compact and stable light sources that can replace bulk solid-state lasers. To generate high-power pulses, we used stretched-pulse mode locking. The average power and pulse width of the output pulse from the fiber laser that we developed were 109 mW and 2.1 ps, respectively. The dispersion of the output pulse was compensated with an external single-mode fiber of 2.5 m length. The pulse was compressed from 2.1 ps to 93 fs by dispersion compensation. The pulse emitted from this fiber laser has an energy sufficient to generate two photon recording effectively, so the fiber laser we have developed is possible to use as a light source of three-dimensional optical memory.

A widely wavelength-tunable ultrashort-pulse fiber-laser source has been demonstrated using a high-power mode-locked ytterbium (Yb)-doped fiber laser and a highly nonlinear photonic crystal fiber (PCF). The Yb-doped fiber laser produces 66-fs ultrashort pulse at the wavelength of 1.05 mum. The pulse energy and the peak-power are 2 nJ and 20 kW, respectively. By injecting this pulse into the highly nonlinear PCF, soliton and anti-Stokes pulses are generated in the wavelength regions of 1.05-1.69 and 0.6-0.7 mum, respectively. The generated soliton pulse is 100-150-fs transform-limited sech2-shaped pulse

We present generation of widely and flatly broadened, low-noise and high-coherence supercontinuum (SC). Pedestal-free high-power Raman soliton pulses are generated as pump pulses and a wideband and flat SC is generated in a normal and small dispersive highly nonlinear fiber. The average power and the full-width at half maximum (FWHM) bandwidth of the generated SC are 40 mW and 580 nm, respectively. The spectral shape is very flat and smooth. The flat spectrum with ±1 dB uniformity is obtained at wavelength region of 1370–1890 nm. The generated SC shows low relative intensity noise (RIN) and high degree of coherence.

46 fs, 4.0 nJ pedestal free high power ultrashort pulse was generated using Er-doped similariton amplifier seeded by nanotube fiber laser. An octave spanning coherent supercontinuum was generated in highly nonlinear normal dispersion fiber.

Authors have been investigating highly functional ultrahoshort pulse fiber laser using single wall carbon nanotube. High power supercontinuum was generated at 1.7 μm wavelength region, and highly sensitive and penetrative ultrahigh resolution OCT was demonstrated.

We demonstrated wideband wavelength tunable narrow linewidth pulses and high quality super continuum using fiber lasers with carbon nanotube. Ultrahigh resolution optical coherence tomography and spectroscopic measurement were demonstrated.

Ultrahigh-resolution OCT in 1.9 mm wavelength region was demonstrated using fiber laser supercontinuum. The wavelength dependence of imaging was investigated, and the decrement in attenuation coefficient in longer-wavelength was confirmed for tooth sample.

Widely broadened high-quality supercontinuum is generated using high power soliton from ultrashort pulse fiber laser system with carbon nanotube. Temporal distribution of generated SC was directly observed using cross-correlated frequency resolved optical gating technique.

Optical frequency comb system based on Er-doped fiber laser with single wall carbon nanotube polyimide film was developed. Narrowing of fceo beat spectrum was achieved through dispersion management of fiber laser cavity.

Optical coherence tomography (OCT) is a non-invasive optical imaging technology for micron-scale cross-sectional imaging of biological tissue and materials. We have been investigating ultrahigh resolution optical coherence tomography (UHR-OCT) using fiber based supercontinuum (SC) source. Although UHR-OCT has many advantages in medical equipments, low penetration depth is a serious limitation for wider applications. Recently, we have demonstrated high penetration depth UHR-OCT by use of fiber based Gaussian shaped SC source at 1.7 μm center wavelength. However, the penetration depth has been limited by the low power of SC source. In this paper, to realize deeper penetration imaging, we have developed the high power Gaussian shaped SC source at 1.7 μm wavelength region based on the custom-made Er-doped ultrashort pulse fiber laser with single-wall carbon nanotube and nonlinear phenomena in fibers. This SC source has 43.3 mW output power, 242 nm full-width at half maximum bandwidth, and 109 MHz repetition rate. The repetition rate and average power were almost twice as large as those of previous SC source. Using this light source, 105 dB sensitivity and ultrahigh resolution of 4.3 μm in tissue were achieved simultaneously. We have demonstrated the UHR-OCT imaging of pig thyroid gland and hamster’s cheek pouch with this developed SC source and compared the images with those measured by the previous SC source. We have observed the fine structures such as round or oval follicles, epithelium, connective tissue band, and muscular layer. From the comparison of the UHR-OCT images and signals, we confirmed the improvement of imaging contrast and penetration depth with the developed SC source.

We have been investigating ultrahigh resolution optical coherence tomography (UHR -OCT) imaging of lung tissues using fiber based super continuum (SC) sources. The high pow er, low -noise, Gaussian shaped SC generated with ultrashort pulses and optical fibers at several wavelength regions were used as the broadband light sources for UHR -OCT. Since the lung con sists of tiny alveoli which are separeted by thin wall, the UHR -OCT is supposed to be effective for lung ima ging. The normal and disease d lung tissues were observed without invasive procedures to the lung itself. The clear images of alveoli were observed with index matching effect by saline. In this work, we investigated t he three -dimensional UHR -OCT imaging of lung structure. The lung s of rat s inflated with 10% formalin at 5 cmH 2 O, 15 cmH 2 O, and 20 cmH 2 O pressure were prepared as the sample for investigation of size and shape of the lung structure. T hese samp les were fixed with 10% formalin . T he inter alveolar sept a, thin walls separat ing the alveoli , w ere clearly observed. The difference of size and shape of alveoli and thier three -dimensional network was clearly observed from the UHR -OCT images. The clear images of alveoli were observed with index matching effect of 10% formalin . We investigated the wavelength dependence of 3D UHR -OCT image of lung structure at 800 nm, 1060 nm, and 1 700 nm wavelength regions . The 3D UHR -OCT images of structure of rat lung were clearly obser ved in all wavelength regions and wavelength dependence of imaging was discussed . Keywords: optical coherence tomography, super continuum, ultra -high resolution, lung