Integrated demultiplexing and amplification of coherent optical combs.

The explosive growth of the internet during the last few decades has been enabled by two complementary innovations in optical communications: the use of multiple optical channels within a single optical fibre, and the increase in the bandwidth of individual channels to hundreds of Gbps. Further increases in overall bandwidth look to be provided by more spectrally efficient optical superchannels that use coherent sub-carriers generated using optical orthogonal frequency division multiplexing (OFDM). Yet, a cost effective way of generating these signals has not been demonstrated. One crucial, but missing piece is an effective means to separate the closely frequency spaced optical sub-carriers from the coherent optical comb before placing information on each sub-carrier, and thus creating the OFDM signal. Here, we demonstrate a flexible strategy implemented in a compact photonic integrated circuit (PIC) that is used to separate and amplify these sub-carriers using on-chip injection locking.

Monolithically integrated low linewidth comb source using gain switched slotted Fabry-Perot lasers.

A monolithically integrated low linewidth optical comb is demonstrated by gain switching of a three-section laser device. The device consists of a slave and master section separated by a shared slotted mirror section. Wavelength tunability has been demonstrated by varying the electrical bias of each section. The number of comb lines is shown to almost double with the addition of optical injection from the master section into the slave. The unmodulated device has a full width half max linewidth of ∼ 500 kHz, while the comb line set were measured to be ∼ 600 kHz, with little degradation as a result of gain switching. The FSR (free spectral range) of the demonstrated comb is 4 GHz, which is tunable within the bandwidth of the device, with a central wavelength of 1580.3 nm.

10 Gb/s InP-based Mach-Zehnder modulator for operation at 2 µm wavelengths.

We report on the first InP-based Mach-Zehnder modulator (MZM) employing quantum-confined Stark effect (QCSE) for operation around 2000 nm. The polarization sensitive device is based on 15 compressively strained quantum wells and achieves an electro-optic (EO) bandwidth of at least 9 GHz, with a DC extinction ratio of ~9 dB, and a V(π)L ~9.6 V.mm. We demonstrate back-to-back communication with a 10 Gb/s pseudo-random bit sequence (PRBS) of length 2(7)-1 at a wavelength around 2000 nm.

On-chip optical phase locking of single growth monolithically integrated Slotted Fabry Perot lasers.

This work investigates the optical phase locking performance of Slotted Fabry Perot (SFP) lasers and develops an integrated variable phase locked system on chip for the first time to our knowledge using these lasers. Stable phase locking is demonstrated between two SFP lasers coupled on chip via a variable gain waveguide section. The two lasers are biased differently, one just above the threshold current of the device with the other at three times this value. The coupling between the lasers can be controlled using the variable gain section which can act as a variable optical attenuator or amplifier depending on bias. Using this, the width of the stable phase locking region on chip is shown to be variable.

Massive ovarian edema and contralateral mature cystic teratoma: asymptomatic presentation in a premenarchal female.

BACKGROUND: Massive ovarian edema is a rare entity, which in most cases occurs in adult females presenting with abdominal pain. We present an unusual case associated with contralateral teratoma in a premenarchal female. CASE: A 13-year-old asymptomatic female presenting with an abdominopelvic mass was referred to the gynecological oncology unit with complex bilateral pelvic masses seen on ultrasound. A combination of computed tomography and repeat ultrasound demonstrated a solid mass containing numerous subcentimeter cysts inseparable from a mature teratoma. Exploratory surgery resulted in unilateral oophorectomy and contralateral cystectomy. Pathology confirmed massive ovarian edema and contralateral mature teratoma. SUMMARY AND CONCLUSION: Recognition of this rare condition is important to avoid overtreatment of massive ovarian edema. Intraoperative biopsy is recommended as an alternative to oophorectomy in this patient group.

Strain and scattering related spectral output of 1.3microm InGaAsP semiconductor diode lasers.

A correlation between the spectral output of 1.3 microm InGaAsP semiconductor diode lasers and the distribution along the length and width of the active region of strain and scattering centers is reported. The strain and scattering center distributions in the active region were obtained by measuring and analyzing the spatially resolved and polarization resolved electroluminescence along the active region of the lasers. Measurements were made on gain-guided, planar buried heterostructure, and arrowhead buried crescent lasers. The results suggest that the material properties of the laser structure affect the longitudinal mode spectrum.

Spatially and polarization resolved electroluminescence of 1.3-microm InGaAsP semiconductor diode lasers.

A technique for obtaining spatially and polarization resolved maps of the electroluminescence along the length of 1.3-microm InGaAsP semiconductor diode lasers is described. The technique yields valuable information on the mechanical strain and uniformity of material in the active region. Measurements on thirty lasers of two different types-planar buried heterostructure (PBH) and gain guided-are summarized. This technique provides a means of correlating operating characteristics of the lasers with the physical properties of the laser material. Large differences between PBH and gain guided lasers are found. PBH exhibit typically a larger average value of strain and more scattering centers than gain guided lasers. A laser with a bent active region exhibited spectral bistability with respect to temperature. The strain distribution in the active region was observed to change during the first few hours of high temperature aging.