Operation of a tunable tandem-type low-coherence light source with high spectral brightness based on commercially available optical elements (superluminescent diode, semiconductor optical amplifier, and bulk dwiffraction grating) is studied experimentally. A unique combination of the output source characteristics, namely, a spectral power density of 36 mW nm −1 , a wavelength tuning range of 35 nm (834 – 869 nm), and a more than 20-dB excess of the central peak intensity over the superluminescent pedestal, is experimentally obtained. It is shown that the output radiation spectrum with a width of 1.4 nm has a smooth bell-shaped profile with side lobes lying below the superluminescent pedestal. It is proved that such a light source is of practical interest for various applications.

We report a laser with a linear external cavity containing a near-IR injection semiconductor optical amplifier as a gain element and two acousto-optic tunable filters (AOTFs) with quasi-collinear interaction of acoustic and light waves. At identical frequencies of RF signals that control the filters and ensure compensation for the Doppler frequency shift of light passing through the AOTFs, the steady-state laser emission linewidth can be reduced to about 25 MHz, which is almost three orders of magnitude smaller than that in the case of one filter (20 GHz). The position of the emission line, which remains narrow, slowly fluctuates within a spectral range about 3 Glitz wide, which seems to be due to the large length of the external cavity and insufficient thermal stabilization of its components. This does not prevent us from obtaining light with a large coherence length. In emission wavelength sweep mode, the instantaneous emission linewidth increases with tuning rate, reaching 0.022 nm (8.8 GHz) at the highest tuning rate: 10(4) nm s(-1). In the case of automatic control over the output optical power at a level of 3 mW, the tuning range is 815-875 nm. Such instruments are of practical interest for optical coherence tomography, spectroscopy, optical metrology, and other application areas.

A tunable laser containing a recently developed travelling wave semiconductor optical amplifier (SOA) of the red spectral region as an active element and an acousto-optic tunable filter in an external fibre ring cavity is studied. Continuous wavelength tuning was achieved within a spectra band up to 20 nm wide with a rate up to 104 nm s−1 at a spectral linewidth below 0.04 nm and a cw output power up to 2 mW. The use of one more similar SOA as an output power amplifier made it possible to increase the output power to 15 mW.

Tunable semiconductor laser in red visible spectral range of 670-690 nm is investigated. Swept laser is based on a recently developed traveling wave semiconductor optical amplifier (SOA) of red spectral range as an active element and an acousto-optic tunable filter (AOTF) in an external fiber ring cavity. Tuning band of up to 20 nm, spectral linewidth below 0.04 nm, sweep speed of up to 10(4) nm/s and CW output power of up to 2.0 mW are obtained. Master-Oscillator Power Amplifier (MOPA) system permitted to increase the output power up to 15 mW with a laser used as a master oscillator and an external SOA - as a power amplifier. We believe the red source may find applications in swept source optical coherence tomography.

Summary form only given. We demonstrate a semiconductor laser with a linear external resonator containing an injection semiconductor optical amplifier (SOA) of the 840 nm range as an active element and two acousto-optic tunable filters (AOTFs) with a quasi-collinear interaction of light and acoustic waves. Studies have shown that an optical scheme of a semiconductor laser with an external linear resonator containing two AOTFs that compensate for the Doppler shift of the optical frequency can significantly narrow the optical spectrum in both the stationary mode of operation and in the wavelength sweep mode in comparison with a scheme without the Doppler shift compensation [1-2]. In the stationary mode of operation, the laser linewidth reaches 25 MHz (FWHM) with a zero mismatch between the frequencies of the AOTF control signals (Figure 1). It is almost three orders of magnitude less than that with a single AOTF configuration. In the wavelength sweep mode, the laser emission line is broadened, but does not exceed 0.022 nm (8.8 GHz) at the maximum wavelength tuning speed of the AOTF - 10000 nm/sec. The study shows the feasibility of the tunable semiconductor laser as a commercial device, with the following technical parameters: output optical power of 3 mW; wavelength tuning range of 815875 nm; maximum sweep speed of 10000 nm/sec; instantaneous spectral width when tuning of <; 0.025 nm; excess of a maximum of the spectral line over a superluminescent background of >40 dB (Figure 2). Such devices are of practical interest for optical coherence tomography (OCT), spectroscopy, optical metrology.

We demonstrate a tunable narrow linewidth semiconductor laser for the 840 nm spectral range. The laser has a linear cavity comprised of polarization maintaining (PM) fiber. A broadband semiconductor optical amplifier (SOA) in in-line fiber-coupled configuration acts as a gain element. It is based on InGaAs quantum-well (QW) active layer. SOA allows for tuning bandwidth exceeding 25 nm around 840 nm. Small-signal fiber-to-fiber gain of SOA is around 30 dB. A pair of acousto-optic tunable filters (AOTF) with a quasi-collinear interaction of optical and acoustic waves are utilized as spectrally selective elements. AOTF technology benefits in continuous tuning, broadband operation, excellent reproducibility and stability of the signal, as well as a high accuracy of wavelength selectivity due to the absence of mechanically moving components. A single AOTF configuration has typical linewidth in 0.05-0.15 nm range due to a frequency shift obtained during each roundtrip. A sequential AOTF arrangement enables instantaneous linewidth generation of <0.01 nm by compensating for this shift. Linewidth as narrow as 0.0036 nm is observed at 846 nm wavelength using a scanning Fabry-Perot interferometer with 50 MHz spectral resolution. Output power is in the range of 1 mW. While the majority of commercial tunable sources operate in 1060-1550 nm spectral ranges, the 840 nm spectral range is beneficial for optical coherence tomography (OCT). The developed narrow linewidth laser can be relevant for OCT with extended imaging depth, as well as spectroscopy, non-destructive testing and other applications.

Tunable semiconductor laser for 1025-1095 nm spectral range is developed based on the InGaAs semiconductor optical amplifier and a narrow band-pass acousto-optic tunable filter in a fiber ring cavity. Mode-hop-free sweeping with tuning speeds of up to 104 nm/s was demonstrated. Instantaneous linewidth is in the range of 0.06-0.15 nm, side-mode suppression is up to 50 dB and polarization extinction ratio exceeds 18 dB. Optical power in output single mode fiber reaches 20 mW. The laser was used in OCT system for imaging a contact lens immersed in a 0.5% intra-lipid solution. The cross-section image provided the imaging depth of more than 5mm.

We have developed two new types of lasers based on quantum-confined semiconductor optical amplifiers with an acousto-optic tunable filter in an external fibre ring cavity. The lasers offer continuous wavelength tuning ranges from 780 to 885 and from 880 to 1010 nm, 20 mW of cw output power, and a tuning rate up to 10(4) nm s(-1) at an instantaneous spectral linewidth less than 0.1 nm.

A series of tunable lasers of the 750-1100 nm spectral range is developed based on the novel broadband semiconductor optical amplifiers (SOAs) and acousto-optic tunable filters (AOTFs) in an external fiber ring cavity. Mode-hop free tuning ranges of up to 100 nm and tuning speeds of up to 10 5 nm/s are demonstrated. Instantaneous linewidths in the range of 0.05-0.15 nm, side-mode suppression of more than 50 dB and polarization extinction ratio of more than 18 dB are observed. Output optical power of 1-3 mW in single-mode fiber can be further amplified up to 30 mW utilizing external amplification based on the same SOAs.

The series of travelling-wave semiconductor optical amplifiers (SOAs) based on QW-heterostructures used for the production of broadband superluminescent diodes (SLDs) is developed. Small-signal fiber-to-fiber gain of SOA-modules is about 25dB. They possess spectral gain bands of 70-125 nm at 10 dB level. Together they cover the IR-range of 750-1100 nm. Their high reliability at CW output optical power of up to 50 mW ex SMF was demonstrated. An example of the application of one of the developed SOA-modules as an active element of high-performance tunable laser is presented.

We report all-PM-fiber ring external cavity, extremely wide tunable/swept lasers and MOPA sources basing on a newly developed SOAs and acousto-optic filter. Tuning ranges of 100 nm, 90 nm and 70 nm have been achieved at output powers of 1.0 mW, 5.0 mW and 10.0 mW, respectively. Instantaneous linewidth below 0.04 nm and sweeping rate up to 10(4) nm/s had been demonstrated. Power boosting up to 50 mW (PMF) and up to 250 mW (MMF) with tunability of around 50 nm had been also demonstrated by using MOPA systems basing on developed laser and different types of boosting SOAs.

A single-pass optical amplifier with a gain up to 32 dB at a wavelength of 840 nm is developed. Its high reliability is demonstrate data single-mode fibre-coupled cw output power up to 50 mW. Examples of efficient application of this amplifier in MOPA systems are presented.

Experimental data are presented which show that double-pass superluminescent diodes (SLDs) with fibre Bragg grating (FBG) based spectrally selective external reflectors offer emission linewidths in the range 0.1–1.0 nm, i.e., one to two orders of magnitude narrower in comparison with conventional SLDs and considerably broader in comparison with single-frequency semiconductor lasers. Their optical power at the single-mode fibre output reaches 5.0–8.0 mW, and can be raised to 50 mW using a semiconductor optical amplifier.

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text V. R. Shidlovsky, E. V. Andreeva, Y. O. Kostin, P. I. Lapin, A. A. Lobintsov, M. V. Shramenko, and S. D. Yakubovich, "Strained Quantum Well InGaAs/GaAlAs/GaAs SLDs and SOAs for HR OCT at 840 and 1060 nm bands," in Biomedical Optics, OSA Technical Digest (CD) (Optica Publishing Group, 2008), paper BMD80. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Two types of semiconductor optical amplifiers (SOAs) based on a double-layer quantum-well (InGa)As/(GaAl)As/GaAs heterostructure are investigated. The optical gain of more than 30 dB and saturation output power of more than 30 mW are achived at 1060 nm in pigtailed SOA modules. These SOAs used as active elements of a tunable laser provide rapid continuous tuning within 85 nm and 45 nm at output powers of 0.5 mW and more than 30 mW, respectively.

Performance characteristics of recently developed superluminescent diodes (SLDs) based on double quantum-well (InGa)As heterostructure and InAs/AlGaAs/GaAs quantum-dot heterostructure are presented. Emission spectra of these SLDs cover spectral bands 960-1080 nm and 1100-1230 nm respectively. Owing to their usage, combined light sources of BroadLighter series cover now the entire NIR-range of 770-1230 nm. New prototypes of swept-wavelength light sources in the range of 820-1080 nm based on quantum-well broadband SOAs and tunable acousto-optic filters are described.

The effect of a weak optical feedback on the power and spectral parameters of light-emitting modules based on near-IR quantum-well superluminescent diodes (SLDs) is studied. It is shown that even very weak parasitic feedback (k(fb) < -30 dB) distorts the emission spectrum of high-power SLDs and noticeably reduces their output power.

A semiconductor laser with an external fiber cavity based on quantum-well superluminescent diode and tunable acousto-optic filter is investigated. The-tuning range of 60nm, instant linewidth below 0.1 nm and output power of several mW ex SM fiber are obtained. Sweep frequency of up to 200 Hz is demonstrated. The prototype of a portable light source of this kind is manufactured.

A tunable semiconductor laser with a laser amplifier based on a double-pass superluminescent diode as an active element and an acousto-optic filter in an external fibre cavity as a selective element is investigated. A continuous spectral tuning is achieved in a band of width 60 nm centered at a wavelength of 845 nm and the 'instant' linewidth below 0.05 nm is obtained. The sweep frequency within the tuning range achieves 200 Hz. The cw power at the output of a single-mode fibre was automatically maintained constant at the level up to 1.5 mW.