Musubu Koishi

Temporal characteristics of picosecond continuum as revealed by a two-dimensional analysis of streak images

Abstract A two-dimensional analysis has been made for streak images of picosecond continua generated in D2O, CCl4, saturated aqueous solution of KDP, H3PO4 and quartz block. Their pulse width and distribution of arrival time at the streak camera were determined as a function of the wavelength.

DEVELOPMENT OF A NEW FLUORESCENCE DECAY MEASUREMENT SYSTEM USING TWO-DIMENSIONAL SINGLE-PHOTON COUNTING

Abstract A new fluorescence decay measurement system has been developed. The system consists of a spectrograph and a new two-dimensional photon counter. The combination enables measurements to be made of the fluorescence decay as a function of time and wavelength simultaneously. The time resolution is better than 5 ps with deconvolution processing, and the wavelength resolution is approximately 0.15 nm with 1200 grooves mm−1 gratings. The dynamic range is 105. The instrument response function (IRF) of the system is nearly gaussian, and has no tail or “after pulses” which are commonly observed using a photomultiplier in a time-correlated photon counting (TCPC) system. Therefore fast fluorescence decay of several tens of picoseconds can be measured accurately. In addition, the two-dimensional single-photon counting can be performed without wavelength scanning, so that the wavelength-dependent fluorescence decay can be easily and direcly observed with a fast throughput and a high signal-to-noise ratio. The principle of two-dimensional photon counting is discussed together with characteristics including linearity and statistical behavior.

New femtosecond streak camera with temporal resolution of 180 fs

We describe a new design and measure data of a femtosecond streak camera with an electromagnetic focusing type streak tube. In order to reduce the temporal dispersion of photoelectrons in the streak tube, an acceleration electric field near the photocathode was achieved to 8.75 kV/mm applying a high voltage pulse to the dc biased-photocathode. We have developed a high speed deflection circuit and a Meander-type traveling wave deflector, and obtained high sweep speed of 8.76 X 108 m/s on the phosphor screen. A measured data of 180 fs was obtained with 100 photoelectrons using colliding-pulse passively modelocked ring dye laser for the light source. Dynamic ranges of 10 and 20 were achieved at the temporal resolutions of 200 fs and 330 fs, respectively.

Picosecond time-resolved near-IR spectra of C60 excited states by pump-probe measurements using a probe beam based on broad-band optical parametric generation

Picosecond time-resolved absorption spectra of C60 singlet and triplet excited states are observed in the near-IR region in the region 700–1300 nm by the pump-probe technique using a probe beam based on broad-band optical parametric generation (OPG) in β-barium borate (BBO) pumped by a picosecond laser pulse at 532 nm and using an InGaAs multichannel detector.

Infrared Sensitive Universal Streak Camera For Use In 1.0 To 1.6 µm Wavelength Region

An infrared sensitive synchroscan streak camera for use in the wavelength region of 1.0 to 1.6 μm is described, including system configuration, absolute photocathode sensitivity, system dynamic range, and its application. Linear (y=1) dynamic ranges of more than 103 at 1.3 and 1.5 μm wavelength have been demonstrated to confirm a single photon reaction in the photocathode at the practical power density level, using ultrashort light pulses from laser diodes. Applications of the system for direct and linear measurement such as picosecond time-resolved spectroscopy of diode laser pulses at 1.3 and 1.5 μm wavelength are also discussed. The system works in single-shot mode as well as synchroscan, by changing a plug-in. This new technique can be widely utilized for direct, linear, real-time and multichannel measurement of ultrafast optical phenomena in the wavelength range of 1.0 to 1.6 μm.

Universal Streak Camera

A universal streak camera which works in synchroscan and single-shot modes with 3 plug-ins (synchroscan, fast and slow) has been developed utilizing a microchannel plate-incorporated streak tube. The synchroscan plug-in features low jitter of less than 4 ps, and high-speed sine-wave deflection from 80 to 160 MHz, achieving a limiting temporal resolution of 5 ps. The fast plug-in offers temporal resolution of better than 2 ps with triggering jitter of less than t20 ps. The slow plug-in provides longer time windows from 10 ns to 1 ms/15 mm in 16 ranges. Shutter operation down to 100 ns in duration is available with a maximum repetition rate of 1 - 10 KHz for the 3 plug-ins. An on-off ratio of more than 1:106 has been achieved by using double gate operation at photocathode and built-in microchannel plate.

Two-Dimensional Sweeps Expanding Capability And Application Of Streak Cameras

New two-dimensional sweeps of streak cameras; elliptical and high-dense sine-curve scans, have been demonstrated to be an excellent and useful method expanding its performance and application. These have been accomplished by applying a sinusoidal or ramp voltage to the second deflection (horizontal) plate of a synchroscan streak tube. The elliptical scan has enabled direct and time-resolved spectroscopic measurement of highly repetitive optical-pulses in the range of several gigaherts and long decay times in the order of one-half the sweep period. The high-dense sine-curve scan has allowed measurement of fluctuations of pulse-shapes and pulse-intervals in a highly repetitive pulse train, and jitter among driving signals of a mode-locker, pumping pulses and oscillating pulses of an actively mode-locked dye laser.

A New Picosecond Synchroscan Photometer

A picosecond synchroscan photometer has been developed to obtain a picosecond temporal resolution and an improved dynamic range of more than 105 : 1, utilizing a newly developed synchroscan streak tube and a direct photomultiplier readout. Advantages include a potentially improved S/N ratio, a lower detection threshold and reduction in cost. A greatly improved high dynamic range of 2 x 105 : 1 with a temporal resolution of better than 47 ps has been demonstrated, by measuring picosecond pulses from a laser diode. The limiting time resolution of this system is estimated to be =10 ps. This technique and its limitations are discussed.

New femtosecond streak camera

This paper presents a new design and measured data of a femtosecond streak camera. In order to reduce the temporal dispersion of photoelectrons in the new streak tube, an acceleration electric field near the photocathode was achieved to 8.75 kV/mm applying a high voltage pulse to the dc biased-photocathode. We have developed a high speed deflection circuit and a meander-type traveling wave deflector, and obtained high sweep speed of 8.76 X 108 m/s on the phosphor screen. A temporal resolution of 180 fs was obtained with 100 photoelectrons using colliding-pulse passively modelocked ring dye laser for the light source. Dynamic ranges of 10 and 20 were achieved at the temporal resolutions of 200 fs and 330 fs, respectively.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Application of picosecond time resolved photoluminescence mapping for the characterization of semi-insulating GaAs wafers

Abstract Decay of the band-edge photoluminescence (PL) from semi-insulating GaAs wafers and two-dimensional maps of the PL decay time and PL intensity of a wafer on a picosecond time scale were measured at room temperature using systems which consist of a synchronously pumped dye laser, a laser diode and a streak camera. The temporal trace of the PL was separated into at least two different decay components with decay times of about 40 and 150 ps, respectively. Two-dimensional maps of the band-edge PL decay time for semi-insulating GaAs wafers have been successfully obtained using a streak camera combined with a laser diode driven by a short pulse current. PL decay time gradually varied over the wafer in reasonable association with the PL intensity. Most significant changes in decay time and PL intensity were seen around the scratch on the wafers.