Search

A tunable laser optical source equipped with wavelength and mode-hop monitors was developed to compensate for thermal expansion of the medium in holographic data storage. The laser's tunable range is 402-409 nm, and supplying 90 mA of laser diode current provides an output power greater than 40 mW. The aberration of output light is less than 0.05 [lambda]rms. The temperature range within which the laser can compensate for thermal expansion of the medium is estimated based on the tunable range, which is [+ or -]13.5 [degrees]C for glass substrates and [+ or -]17.5 [degrees]C for amorphous polyolefin substrates. OCIS codes: 090.7330, 140.3600, 210.2860.

We propose and demonstrate a tunable fiber laser based on an optical circulator (OC) and two tunable fiber Bragg gratings (TFBGs). The OC acts as a pump power router to improve the pumping efficiency, and a 4% increase in overall conversion efficiency has been observed. The combined tuning spectra range of two TFBGs could cover the entire C-band spectrum from 1530 to 1560 nm. Stable laser output power above 10 dBm is obtained using 1.9 m of erbium-doped fiber and TFBGs with 50% reflectivity. With power equalization by using variable optical attenuators, the power variation is less than 0.1 dB in the whole C band with narrow linewidth of 0.05 nm. A signal-to-noise ratio of 60 dB and a continuous tuning resolution of 0.5 nm have been achieved. The TFBG-based tunable fiber laser can be a promising light source for WDM transmission and fiber sensor applications. OCIS codes: 140.3510, 140.3600, 060.2330, 060.1810.

This paper presents the design of a real pivot formed by a double-clamped beam for the rotational tuning structures in microelectromechanical systems (MEMS) tunable lasers. Micromechanical properties such as beam deformation, pivot position and pivot shift are investigated and compared with the virtual pivot formed by a cantilever beam. It is shown that the real pivot has negligible shift when subjected to load and fabrication error owing to its feature of structural symmetry, while the virtual pivot suffers from significant pivot shift, which would severely limit the wavelength tuning range. The two pivot designs are implemented into MEMS tuning structures that are fabricated by deep etching and released using a dry release approach. The real pivot measures a depth variation of 16% over the double-clamped beam but maintains the symmetry to the midpoint, and is still able to produce a rotation angle of 4.7[degrees]. In contrast, the virtual pivot has a depth reduction of 4% over the cantilever beam, but achieves only a 2.4[degrees] rotation due to the pull-in problem originated from the severe pivot shift. The real pivot design is more suitable for the MEMS tunable lasers as it is simple, symmetric, robust, and suitable for single-chip integration. [2006-0112] Index Terms--External-cavity tunable lasers, microelectromechanical systems (MEMS), micromechanics, pivot, rotary comb drive.

We report the implementation of a tunable, narrow-spectral-bandwidth, pulsed, four-pass dye-laser amplifier with strongly reduced amplified spontaneous emission. We present temporal pulse profiles, pulse spectra, and gain measurements of the amplifier output for the case of Coumarin 307 dye as the gain medium, seeded at wavelengths of ~508 nm and pumped at 355 nm. OCIS codes: 140.2050, 140.3280, 300.6320, 300.6360.

The optical feedback mechanisms in coherently tunable lasers are investigated and the relation to an electromagnetically induced transparency process that happens in the conduction intersubband transitions is discussed. Results show that the sign of the tuning process, red or blue shift, is decided by the frequency of this field, after proper choice of the corrugation periods.

The devices fabricated with gratings that contain both strong surface-metal interaction, and an effective index step, are reported. Results suggest that metal-filled distributed Bragg reflector (DBR) gratings are useful for wavelength-stable, broadly tunable DBR devices, which simultaneously achieve narrow spectral linewidths.

We report on cw tunable green laser light generation from a Nd:YV[O.sub.4] laser operating at 1342 nm. Visible radiation was produced by a frequency mixing of pump and laser radiation inside an intracavity KTP crystal. When Nd:YV[O.sub.4] was diode pumped, green laser was tunable from 503 to 505 nm. The green tuning range increases up to 22 nm when a Ti:sapphire laser is used as the pump source. In nonoptimal conditions, and for a pump power of 650 mW, green power was above 3 mW and close to 0.1 mW for Ti:sapphire and diode pumping, respectively. OCIS codes: 140.3580, 140.7300, 140.3530, 190.2620.

We report the successful demonstration of a near-IR tunable laser (1525.4-1558.2 nm) that uses an integrated LiTa[O.sub.3] deflector in combination with a reflection grating as an electronically tunable filter. The electro-optic deflector is a unique integrated optical device and consists of a horn-shaped array of electro-optic prisms in series. The almost 33 nm of tuning covers a wavelength region of high interest to the communications industry (1527-1550 nm). OCIS codes: 140.0140, 140.3600, 230.0230, 230.2090, 230.3120, 160.2260.

A local oscillator for laser-pumped gas-cell rubidium frequency standards was described. The effects caused by noise in the microwave and laser sources were reduced to achieve a frequency stability of one order of magnitude better than other lamp-pumped devices. The short-term frequency stability was affected by the phase modulation noise in the microwave synthesizer, the photocurrent noise on the detector and the combined effect on laser frequency noise with light shift.

A narrow-band, precisely tunable dye laser pumped by an injection-seeded YAG laser is described. The laser achieves an output of 100 mJ/pulse and 40% efficiency when one uses Rhodamine 6G dyes. The output pulse is Gaussian both in time and spatial profile. The laser oscillator employs an intracavity etalon that is repetitively pressure scanned over one free spectral range while the grating successively steps to consecutive etalon modes. We pressure scanned the etalon under computer control using a bellows. Methods are described for calibrating the tuning elements for absolute precision. We demonstrated that the laser has an absolute precision of [+ or -]0.4 pm over a 1.0-nm scan. This accuracy is achievable over the wavelength range of a dye.

Epitaxial growth of an asymmetric GaAscladding laser structure yields ridge-waveguide distributed Bragg reflector (RW-DBR) lasers with asymmetric cladding and narrow linewidths. The grating and ridge waveguide are prepared after the single epitaxial growth. The RW-DBR lasers have a threshold current of 9 mA, slope efficiency of 0.3 W/A and a T(sub O) of 100 kelvin. Heating of the DBR with current injection produces a 8 nm wavelength tuning. A minimum spectral linewidth of 36 kHz is obtained at an output power of 20 mW.

We have constructed an optical parametric oscillator to generate 75-ps near-transform-limited pulses with wavelengths tunable about 1.053 [[micro]meter] for use in pump-probe studies of self-focusing. The singly resonant oscillator uses a Brewster-cut Li[B.sub.3][O.sub.5] crystal that is oriented for type-II phase matching and synchronously pumped by the amplified and frequency-tripled pulse trains from a mode-locked and Q-switched Nd:YLF laser. An intracavity Pockels cell is used to switch out single 0.5-MW pulses at rates of I to 10 Hz. The design, construction, and performance of the oscillator are discussed. Measured performance is compared with design predictions and with detailed numerical simulations.

The static and dynamic analysis of a tunable two-section high-speed distributed feedback laser shows that the gain-lever effect enhances the frequency modulation (FM) response of the laser. The modulation bandwidth, however, decreases. One section of the laser is flat and the other has a grating corrugation. The DC bias of the two sections affects the dynamic response of the device.

We present a new, accurate frequency-tuning mechanism in a grazing-incidence cavity for single-longitudinal-mode oscillation in a tunable laser. A wedge prism with a small apex angle is inserted between the tuning mirror and the grating for accurate frequency tuning. In this configuration, the laser frequency can be tuned precisely by rotation of the wedge instead of the tuning mirror. This fine-tuning mechanism offers the ability to tune the frequency over more than 400 GHz without mode hop and with a tuning accuracy that is 2 orders of magnitude larger than that of conventional tuning methods. Key words: Frequency-tuning mechanism, wedge prism.

A reliable room-temperature-operated, pulsed LiF:F3+ color-center laser with a two-mirror cavity has been constructed. This laser is useful as a tunable, green, coherent light source. The laser has shown a long-lifetime operation and remarkable amplitude stability by pumping with a dye laser. The laser light has a peak at 543 nm. The slope efficiency is approximately 2%, and the pump threshold is approximately 75 mW.

Research was conducted to examine a widely tunable laser structure that presents a good tradeoff between high performances and technological processing simplicity. The sampled-grating distributed Bragg reflector laser was designed and realized. Results prove the ability of these lasers to be employed as tunable emitters in wavelength-division-multiplexed applications. Improvements that are needed for the practical implementation of the lasers for wavelength-division-multiplexed optical fiber communications are proposed.