Stimulated Raman scattering (SRS) microscopy allows label-free chemical imaging based on vibrational spectroscopy. Narrowband excitation with picosecond lasers creates the highest signal levels and enables imaging speeds up to video-rate, but it sacrifices chemical specificity in samples with overlapping bands compared to broadband (multiplex) excitation. We develop a rapidly tunable picosecond...

A tunable, gain-clamped (GC) double-pass Erbium-doped fiber amplifier (EDFA) with a linear laser-cavity configuration has been demonstrated. It solves the problems existing in the conventional linear-cavity GC-EDFA based on two fiber Bragg gratings (FBGs), in which the clamped-gain is very difficult to be tuned. In the new GC-EDFA, the lasing oscillation for clamping the gain is produced in a l...

Abstract Developing semiconductors with broad gain bandwidth has always been at the forefront of laser technologies. The variation in feedback resonators can provide a useful tool for producing relatively wide range discrete lasing wavelengths. However, wavelength is limited by fundamental semiconductor itself. Gain engineering full‐color though remains daunting challenge. Considering abundant ...

The lack of a high-power, relatively low-cost and compact terahertz (THz) source in the range 0.3-3x10 Hz is the major obstacle in progressing on biomedical and material studies at these wavelengths. A high-gain, single pass seeded FEL technique allows to obtain high power THz pulses of a high spectral brightness. We describe an ongoing project at the Neptune laboratory where a ~ 1kW seed pulse...

An idea of adjustable gain in order to obtain controllable features is very useful for design of tunable oscillators. Several active elements with adjustable properties (current and voltage gain) are discussed in this paper. Three modified oscillator conceptions that are quite simple, directly electronically adjustable, providing independent control of oscillation condition and frequency were d...

Erbium-doped aluminum oxide amplifiers with varying erbium concentration have been fabricated on thermally oxidized silicon substrates. Significant net internal gain of up to 1.6 dB/cm has been measured at 1533 nm for the optimum Er concentration. Furthermore, net gain has been demonstrated over a wavelength range of 40 nm, including the telecom C-band, demonstrating the potential for amplifier...

A 5GHz, 56dB voltage gain Low Noise Amplifier with built-in tunable center frequency and 30MHz bandwidth channel selection filter was implemented using 0.18μm CMOS process. Using compact high quality-factor 3-dimensional solenoid on-chip inductors, the LNA drains 0.9mA current from the 1.5V power supply and has 6.5dB noise figure. The power consumption can be further reduced if a smaller gain i...

there are limited documents about hiv patients switched to second-line antiretroviral therapy (art) in resource-limited countries. we aimed to assess the efficacy of second-line art for hiv patients following first-line art failure. this was a cohort study of hiv/aids patients with first-line art treatment failure switched to second-line art between january 2004 and march 2014, who followed for...