We present a swept source based on a Semiconductor Optical Amplifier (SOA) as a light emitter as well as a gain medium at 850 nm, equipped with a diffraction grating and a 16 kHz resonant scanner. The developed swept source is bidirectional, capable of 32 kHz operation, with a linewidth of 0.08 nm and a tuning range of 12 nm.
We demonstrate a Fourier domain mode locked (FDML) laser centered around 850 nm with a sweeping range of 50 nm, a fundamental repetition rate of 2×416 kHz and an output power of 2 mW. A new cavity design using three chirped Fiber Bragg gratings is required to overcome sweeping limitations caused by high dispersion. Other solutions to address challenges such as high loss and high polarization mode dispersion will be discussed along with performance. A main application of this laser will be retinal imaging, but it might also be applicable for TiCo-Raman and SLIDE microscopy.
Superluminescent diodes (SLDs) of spectral range 730 – 790 nm with strained single quantum-well (SQW) active layer and spatially single mode ridge waveguide were studied experimentally. SLDs with short active channels < 1000 μm have demonstrated broadband emission spectrum with median wavelength near 765 nm, FWHM of up to 60 nm and free space CW output power in the range 2 – 15 mW at 25°C. SLDs with longer active channels have demonstrated output of up to 150 mW and spectral half-width in the range 40 – 20 nm. TM mode was dominant in output emission.
Three types of light sources based on superluminescent diodes (SLDs) of NIR ranges 800 – 880 nm and 860 – 950 nm with spatially single mode active channels were studied. Light-emitting modules have demonstrated free space continuous wave (CW) output power of up to 150 mW and 75 mW ex single mode optical fiber (SMF), at spectral bandwidth of about 25 nm. Master Oscillator Power Amplifier (MOPA) system in which SLD of the first type was used as an active element of a power amplifier and blue-shifted SLD as a master oscillator permitted to broaden spectral bandwidth up to 50 nm at the same output optical power level. The estimated lifetime of these devices is more than 10000 hours. High power combined light source based on two MOPA systems with spectral FWHM of more than 100 nm was realized.
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 104 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.
The optimization of AlGaInP/GaInPAs MQW heterostructure MOCVD growth as well as the improvements of active channel formation and P-contact deposition technologies made it possible to increase significantly external differential efficiency (up to 0.5 mW/mA) and CW catastrophic optical damage threshold (up to 40 mW) of spatially single-mode superluminescent diodes (SLDs) with central wavelength of 675 nm. Preliminary life time tests demonstrated high reliability of the devices at output power 30 mW. The relations of spectral and power characteristics of the SLDs as well as SLDs with central wavelengths of about 660 nm and 690 nm on active channel length, pumping level and temperature were studied. The results of mathematical modeling of combined light sources output parameters that could be made with SLDs and a broadband SM fiber coupler, are presented.
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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.