The potential for improving the penetration depth of optical coherence tomography systems by using light sources with longer wavelengths has been known since inception technique in early 1990s. Nevertheless, development mid-infrared long challenged maturity and fidelity components this spectral region, resulting slow acquisition, low sensitivity, poor axial resolution. In work, a spectral-domain system operating at central wavelength 4 µm an resolution 8.6 is demonstrated. produces...

This paper provides an extensive survey of nonlinear parametric upconversion infrared (IR) imaging, from its origin to date. Upconversion imaging is a successful innovative technique for IR in terms sensitivity, speed, and noise performance. In this approach, the image frequency upconverted form visible/near-IR through three-wave mixing followed by detection using silicon-based detector or camera. 1968, Midwinter first demonstrated short-wave-IR (1.6 μm) visible (484 nm) wavelength bulk...

In this Letter, we demonstrate efficient room temperature detection of ultra-broadband mid-wave-infrared (MWIR) light with an almost flat response over more than 1200 nm, exploiting nonlinear upconversion technique. Black-body radiation from a hot soldering iron rod is used as the IR test source. Placing 20 mm long periodically poled lithium niobate crystal in compact intra-cavity setup (>20 W CW pump at 1064 nm), MWIR wavelengths ranging 3.6 to 4.85 μm are upconverted near-infrared (NIR)...

Femtosecond lasers with high peak power at wavelengths above 2 µm are of interest for generating mid-infrared (mid-IR) broadband coherent light spectroscopic applications. Cr 2+ -doped ZnS/ZnSe solid-state uniquely suited since they provide an ultra-broad bandwidth in combination watt-level average power. To date, the semiconductor saturable absorber mirror (SESAM) mode-locked Cr:ZnS(e) have been severely limited due to lack suitable 2.4-µm SESAMs. For first time, we develop novel...

Semiconductor saturable absorber mirrors (SESAMs) are widely used for modelocking of various ultrafast lasers. The growing interest SESAM-modelocked lasers in the short-wave infrared and mid-infrared regime requires precise characterization SESAM parameters. Here, we present two setups a wavelength range 1.9 to 3 µm precisely measure both nonlinear reflectivity time-resolved recovery dynamics. For measurement, high accuracy (<0.04%) over wide fluence (0.1–1500 µJ/cm 2 ) is achieved....

Femtosecond lasers with high repetition rates are attractive for spectroscopic applications sampling rates, power per comb line, and resolvable lines. However, at long wavelengths beyond 2 µm, current laser sources either limited to low output or below 1 GHz. Here we present an ultrafast oscillator operating multi-GHz rate. The produces transform-limited 155-fs pulses a rate of GHz, average 0.8 W, reaching up 0.7 mW line the center wavelength 2.38 µm. We have achieved this milestone via...

We numerically design a compact silicon (Si) based polarization rotator (PR) by exploiting power coupling through phase matching between the TM mode of Si strip waveguide (WG) and TE Si-air vertical slot WG. In such structures, occurs due to horizontal structural asymmetries extremely high modal hybridness refractive index contrast Si-on-insulator (SOI) structure. Design parameters coupler have been optimized achieve PR ~135 μm length at telecommunication wavelength 1.55 μm. Maximum...

Low noise detection with state-of-the-art mid-infrared (MIR) detectors (e.g., PbS, PbSe, InSb, HgCdTe) is a primary challenge owing to the intrinsic thermal background radiation of low bandgap detector material itself. However, researchers have employed frequency upconversion based (UCD), operable at room temperature, as promising alternative traditional direct schemes. UCD allows for use silicon-CCD/camera improve SNR. Using UCD, contributions from nonlinear itself should be evaluated in...

We present the detailed growth and characterization of novel GaSb-based semiconductor saturable absorber mirrors (SESAMs) operating in 2–2.4 µm spectral range. These SESAMs at different wavelengths are bandgap engineered using ternary material compositions without strain compensation. observe that even when thickness quantum wells (QWs) exceeds critical we obtain relaxed do not substantially increase nonsaturable losses. have been fabricated molecular beam epitaxy with a AlAs 0.08 Sb 0.92...

We report the design of a highly nonlinear holey fiber for making mid-infrared light source at 4.36 μm. A solid-core chalcogenide-based index-guided microstructured optical with circular air holes has been exploited to numerically demonstrate wavelength translation via four-wave mixing. employ thulium-doped laser as pump power 5 W. Our simulations indicate that maximum parametric gain 20.5 dB bandwidth 16 nm is achievable in this designed fiber, resulting conversion efficiency more than 17.6%.

Design of a mid-wave IR (MWIR) broad-band fiber-based light source exploiting four-wave mixing (FWM) in meter long suitably designed highly nonlinear (NL) chalcogenide microstructured optical fiber (MOF) is reported. This superior FWM bandwidth (BW) was obtained through precise tailoring the fibers dispersion profile so as to realize positive quartic at pump wavelength. We consider an Erbium (Er3+) doped continuous wave (CW) ZBLAN laser emitting 2.8 micron with average power 5 W....

We present the first modelocked backside-cooled GaSb VECSEL (Vertical External Cavity Surface Emitting Laser) operating above <inline-formula> <tex-math notation="LaTeX">$2 ~\mu \text{m}$ </tex-math></inline-formula>. Using a two quantum well InGaSb SESAM (SEmiconductor Saturable Absorber Mirror) in V-shaped cavity arrangement we obtain femtosecond modelocking at center wavelength of 2061 nm, with pulses as short 324 fs, an average output power high 65 mW repetition rate 3 GHz. An operation...

Cr-doped ZnS and ZnSe are excellent gain mediums for high power broadband ultrashort pulse generation in the 2 – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3~\mu \text{m}$ </tex-math></inline-formula> wavelength range. SESAM modelocked Cr:ZnS oscillators have advantage of reliable, self-starting passive modelocking. We present a diode-pumped, oscillator delivering pulses 189 fs at 550 mW average...

We compare the gain and continuous wave lasing properties of two InGaSb-based vertical external cavity surface emitting lasers (InGaSb VECSEL) with different heat management approaches operating at a center wavelength around 2μm. To date, intracavity heatspreaders have been required for good average output power, which many trade-offs, especially passive modelocking. Here we demonstrate record high power 810 mW without an heatspreader using backside-cooled non-resonant VECSEL chip optimized...

Dual-comb lasers are a new class of ultrafast that enable fast, accurate and sensitive measurements without any mechanical delay lines. Here, we demonstrate 2-µm laser called MIXSEL (Modelocked Integrated eXternal-cavity Surface Emitting Laser), based on an optically pumped passively modelocked semiconductor thin disk laser. Using III-V molecular beam epitaxy, achieve center wavelength in the shortwave infrared (SWIR) range by integrating InGaSb quantum well gain saturable absorber layers...

We present a scheme to estimate the noise equivalent power (NEP) of frequency upconversion detectors (UCDs), detecting mid-infrared (MIR) light. The NEP UCD is combined contribution NEPs from process and photodetector, used for upconverted signal. 2-5-μm MIR range particularly investigated in this letter using bulk periodically poled lithium niobate-based CW-intracavity UCD. measured as 20 fW/√Hz at wavelength 3.39 μm. Here, we showed that limiting factor not (estimated 2.3 μm) but...

This paper presents a theoretical design of chalcogenide glass based tapered microstructured optical fiber (MOF) to generate high power parabolic pulses (PPs) at the mid-IR wavelength (~2 μm). We optimize cross-section by multipole method and studied pulse evolution well-known symmetrized split-step Fourier Method. Our numerical investigation reveals possibility highly efficient PP generation within very short length (~19 cm) this MOF for Gaussian input 60 W peak full width half maximum...

In this Letter, a novel technique for independent control of the phase-matched center wavelength and bandwidth (BW) is demonstrated upconversion detection in 2–4 μm range using fanout lithium niobate (LN) crystal. A compact, all-semiconductor, 975 nm laser delivering 3.5 W power used as pump single-pass configuration. globar (∼800°C) infrared test source. Continuous tuning detected (λc:2.5–3.0 μm) BW (ΔλIR:35–225 nm) has been realized mechanical translation rotation, respectively, LN...

We report on an all-fiber terahertz (THz) radiation source by exploiting nonlinear parametric process in a theoretically designed microstructured-core double-clad plastic fiber (MC-DCPF). The required phase-matching condition is satisfied through suitable tailoring of the dispersion and properties at pump wavelength high-power CO2 laser, with CO laser much lower power acting as seed concomitantly. Our simulated results reveal that THz frequency ∼3 could be realized 3-dB band width 2.13 GHz...

We use numerical simulations to design a hollowcore microstructured polymer optical fiber (HC-mPOF) suitable for broadband, terahertz (THz) pulse transmission with relatively low losses and small dispersion. The HC-mPOF consists of central large air-core surrounded by periodically arranged wavelength-scale circular air holes in hexagonal pattern, embedded uniform Teflon matrix. THz guidance this is achieved exploiting the photonic bandgap (PBG) effect. In our index contrast Teflon-air...

We present the first dual-modelocked femtosecond oscillator operating beyond 2 µm wavelength. This new class of laser is based on a Cr:ZnS gain medium, an InGaSb SESAM for modelocking, and two-surface reflective device spatial duplexing two modelocked pulse trains (combs). The operates at 2.36 µm, each comb, we have achieved FWHM spectral bandwidth 30 nm, average power over 200 mW, duration close to fs. nominal repetition rate 242 MHz with sufficiently large difference 4.17 kHz. also found...

We present improved thermal management of an optically-pumped vertical external cavity surface emitting laser (VECSEL) at a center wavelength around 2 µm. This was achieved with backside-cooled, InGaSb-based VECSEL using hybrid metal-semiconductor Bragg reflector. demonstrate the fabrication such mirror by combining copper 10.5 AlAs 0.08 Sb 0.92 /GaSb distributed reflector (DBR) pairs. Together thin 20 nm SiO diffusion barrier we reach &gt;99.9 % reflectivity allows for thinner gain chip...