We are developing a new light source for swept-source OCT, namely, an external-cavity LD equipped with a KTN
electro-optic deflector. Being free from mechanical resonance, our 1.3-μm laser exhibits scanning range of almost 100
nm up to 200-kHz under a ±300 V deflector driving voltage. Using a semi-empirically derived equation, we find that
KTN's convex lens power degrades the coherence length, and this can be compensated with a cylindrical concave lens.
Such compensation was experimentally confirmed by observing reduction of elliptical beam divergence. OCT images of
a human fingernail are obtained using the swept source.
We present a new light source for the swept-source OCT, that is, an external-cavity LD incorporating an electro-optic
deflector. We use a KTN deflector that is unique in being very fast and simultaneously providing an appreciable
deflection caused by injected carriers. Particularly, high-speed and nearly linear to the applied voltage operation is
attained when KTN crystal is pre-charged. Our 1.3-μm Littman-Metcalf external-cavity laser exhibits static linewidth <
0.1 nm, and a 110-nm scanning range up to 150-kHz under a ±200 V sinusoidal driving voltage to the deflector. Being
free of mechanical resonance, the laser would hopefully realize a faster (in a separate study, deflector itself worked up to
400 kHz) and wavenumber-linear scan that is ideal for the swept-source OCT by designing the waveform of driving
voltage. And as for the resolving power of deflector, while our KTN deflector has only 35 spatial resolvable points, the
number of wavelength points for the swept source clearly exceeds to this limit, which we attribute to line narrowing
effect accompanied by the laser operation. Preliminary OCT images taken using the swept source are also presented.
The hemisphere type SIL of KTaO3 that has a high refractive index was developed. NA 1.84 was achieved by the hemisphere SIL of KTaO3 that has a wide thickness tolerance in combination with a high NA aspherical lens of NA 0.77. Huge capacities ROM of 50-100 GB were evaluated by means of KTaO3 hemisphere SIL. The same playback performance as that of LAH79 SIL was confirmed.
KTa1-xNbxO3 crystal exhibits an extremely large quadratic electro-optic effect, which is 20 times greater than that of LiNbO3. This property makes this crystal attractive for optical signal processing applications. We have successfully prepared a 2-inch KTN crystal that exhibits the largest quadratic electro-optic coefficient ever reported. We have also fabricated a buried optical waveguide with a low transmission loss and demonstrated an optical switch with a driving voltage of 2.6 V and a 92 nsec rise time. This paper reviews the crystal growth, material properties, electro-optic effect, waveguide fabrication, and optical switch operation of KTN crystal.
This paper reviews NTT Photonics Laboratories' recent progress on advanced photonic devices based on dielectric waveguide technologies such as silica-based planar lightwave circuits, LiNbO3 waveguides, and optical fiber.
As the demand for optical fiber communications bandwidth grows, the implementation of signal processing functions using all-optical techniques becomes increasingly attractive. In recent years, a number of methods have been used to perform functions such as wavelength conversion for WDM systems, gated mixing for TDM multiplexing and demultiplexing, spectral inversion for dispersion compensation, and all-optical switching. Three-wave mixing in c(2) media is an attractive approach, presenting a combination of low pump power, wide bandwidth, and negligible degradation of signal to noise ratio. In this paper, we describe optical frequency mixers implemented using annealed proton exchanged waveguides in periodically poled lithium niobate. These devices have been used in a variety of system experiments. We present several WDM demonstrations, including wavelength conversion, dispersion compensation by mid-span spectral inversion, and compensation of Kerr nonlinearities. We also discuss TDM demonstrations such as efficient all-optical gating and multiplexing/demultiplexing of high bit-rate data streams.
As the demand for optical fiber communications bandwidth grows, the implementation of signal processing functions using all-optical techniques becomes increasingly attractive. In recent years, a number of methods have been used to perform functions such as wavelength conversion for WDM systems, gated mixing for TDM multiplexing and demultiplexing, spectral inversion for dispersion compensation, and all-optical switching. Three-wave mixing in (chi) (2) media is an attractive approach, presenting a combination of low pump power, wide bandwidth, and negligible degradation of signal to noise ratio. In this paper, we describe optical frequency mixers implemented using annealed proton exchanged waveguides in periodically poled lithium niobate. These devices have been used in a variety of system experiments. We present several WDM demonstrations, including wavelength conversion, dispersion compensation by mid-span spectral inversion, and compensation of Kerr nonlinearities. We also discuss TDM demonstrations such as efficient all-optical gating and multiplexing/demultiplexing of high bit-rate data streams.
The reliability of a fluoride fiber module generally depends on three factors. They are the lifetime of the fluoride fiber under practical environmental conditions, the reliability of the splice between fluoride and silica fiber in terms of low-loss and low-reflection, and the effectiveness with which the packaging prevents moisture damage. The first factor depends strongly on the fluoride fiber strength. We describe a technique for fabricating fluoride fiber with improved strength and then estimate its lifetime using a static fatigue test. We evaluate the remaining two factors by applying the recommended reliability test program to the fiber modules. We describe the structure of our fluoride fiber module and present the reliability test results with reference to the Bellcore Technical Advisory TA-NWT-001221.
This paper describes the optical amplification characteristics and reliability of praseodymium-doped and erbium-doped fluoride optical fiber amplifiers, with a view to their application in practical optical systems.
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.